Plan
Hold points
| Gate | Stage | What is checked | Record |
|---|---|---|---|
| G1 | Incoming material | Mill test reports checked against the ordered grade (A500, A992, A572); heat numbers logged; rebar, cement, aggregate, admixture, glazing and panel certificates on file. | Receiving log with heat and lot traceability |
| G2 | Steel fabrication | Fit-up check before welding, qualified procedures and welders, 100% visual weld inspection, sampled NDT, dimensional survey, coating thickness. | Weld map and survey sheet per frame |
| G3 | Precast concrete | Rebar, cover, embed and lifting-insert inspection before the pour; fresh-concrete tests; cylinders; stripping strength before handling. | Batch tickets, break results, pour report |
| G4 | Frame and floor assembly | Bolt pretension, squareness by diagonals, flatness, shear-key fit-up against the mating module. | Torque log, as-built dimensions |
| G5 | Rough-in (before close-in) | Plumbing pressure tests, electrical continuity and polarity, duct leakage, insulation and air-barrier inspection. State in-plant inspection hold. | Rough-in test sheets, inspector sign-off |
| G6 | Envelope | Glazing and flashing installed, rail and panel fit, water spray test, blower-door test on the module. | Water and air test reports |
| G7 | Final acceptance | Punch list closed, weight and dimensions recorded, state data plate applied, photo record, shipping release. | Release certificate per module |
| G8 | Transport and set | Route survey, tie-down and bracing check, lift plan and rigging inspection, set tolerances, bolt-up, grouting, joint sealing, local inspection. | Set log, grout cubes, inspector sign-off |
| G9 | Closeout | Joint water test, whole-house air test, thermography, systems commissioning, warranty walk-through. | Commissioning report, warranty file |
33 items
Steel fabrication
| Test or check | Requirement | Applied to a module | Criteria / frequency | Source |
|---|---|---|---|---|
| AISC Certification audit scope for building fabricators AISC · AISC Certification audit policies (Issue 14, 2009) | Certification involves an administrative review, a documentation audit and an on-site audit. On-site auditors sample WPS, PQR and welder performance records against AWS D1.1 (or D1.5 for bridges); records or execution that do not comply with the code lead to a Corrective Action Request. Audit policies also cover material identification, bolt pre-installation verification demonstrations and gauge calibration. | The module frame fabrication shop would hold or seek AISC certification so that its QMS and welding controls are audited by a third party. | app.aws.org | |
| AISC 360 as governing design specification AISC · ANSI/AISC 360 | ANSI/AISC 360 Section B4.2 sets the design wall thickness used for HSS member calculations (0.93 times nominal for A500). Member and connection limit states are checked to 360. | Frame columns, rails, beams and corner connectors are designed to 360; QA documents trace each check back to it. | steeltubeinstitute.org | |
| AISC 341 applicability AISC · ANSI/AISC 341 | In the 2005 edition, 341 applied when the seismic response modification coefficient R exceeds 3, and was not required at R of 3 or less unless the building code requires it. Current-edition wording was not confirmed. | Low-rise modules designed at R=3 or less would normally fall under 360 only; the engineer of record must confirm the R value and code edition used, as 341 adds welding and material requirements. | R greater than 3 triggers 341 (2005 edition text per search summary) | codehub.building.govt.nz |
| Mill test reports and heat traceability Industry practice · EN 10204 3.1 / 3.2 (heat traceability for ASTM A6 / A500 / A992 material) | A mill test certificate reports chemistry and tensile results that are checked against the specification limits, and the heat number on the certificate must match the marking on the product. EN 10204 3.2 is the same as 3.1 plus an independent third-party inspector who witnesses the tests and co-signs. | Every column, rail, beam and plate heat is logged against its MTR at receiving and heat numbers carried onto cut parts and shop travelers. | blog.projectmaterials.com | |
| A500 HSS design wall thickness factor AISC · ASTM A500 / AISC 360 Section B4.2 | A500 allows minus 10% on wall thickness, so AISC design wall thickness is taken as 0.93 times nominal. ASTM A1085 tightens wall tolerance to minus 5% and mass to minus 3.5%, removing the need for the factor. | Frame design calcs use 0.93t for A500 Gr. C HSS; receiving inspection can spot-check wall thickness with ultrasonic gauge against 0.90 x nominal minimum. | Design thickness = 0.93 x nominal; A500 tolerance minus 10%; A1085 minus 5% | steeltubeinstitute.org |
| HSS corner radius assumption Steel Tube Institute · AISC 360-16 Table J2.2 | For weld detailing, HSS corner radius can be taken as 2t (t = design wall thickness); Table J2.2 sets no upper limit on outside radius. Welding in corners is generally avoided; corner welds are a special PJP case. | Weld details for HSS-to-HSS and plate-to-HSS joints should avoid welding across the corner radius where possible, and use effective throat per Table J2.2 where not. | Corner radius taken as 2t for detailing | steeltubeinstitute.org |
| AWS D1.1 coverage of cold-formed corners Steel Tube Institute · AWS D1.1 | D1.1 reproduces AISC effective throat sizes (Table 4.1), allows a reinforcing fillet to increase flare-bevel weld size, and covers preheat/interpass in Clause 5.7. It does not address welding in regions of high cold forming, which may be unconservative. | WPS for HSS should be reviewed by a welding engineer for welds near corners, with extra scrutiny and possibly MT on corner-region welds. | Preheat min for typical HSS grades 32F to 50F up to 3/4 in. thick (article, mainly site welding) | steeltubeinstitute.org |
| Weld toe at HSS corner behaviour Research (J-STAGE) · Cold-formed rectangular HSS study | A 2025 Japanese study of cold-formed rectangular HSS columns found that all specimens initiated a ductile crack at the weld toe at the corner and failed in a brittle manner. | Supports specifying smooth weld profiles and visual/MT checks of weld toes at HSS corners. | jstage.jst.go.jp | |
| Prequalified and qualified WPS AWS · AWS D1.1 | A WPS is a formal written document describing a specific welding procedure; a PQR records a demonstration weld and its test results (tensile, bend, toughness if required). D1.1 Clause 3 lists conditions under which a WPS is exempt from qualification (prequalified); otherwise PQR-based qualification is needed. Inspection acceptance criteria and NDT procedures are in the inspection clause. | One WPS per joint family (HSS to HSS, HSS to plate, plate to beam) kept at the weld station and tied to the welder's qualified process and position. | web-ded.uta.edu | |
| Welder performance qualification and continuity AWS · AWS D1.1 | Per a summary of D1.1 clause 6.2.3, a welder qualification remains valid unless the welder goes more than six months without performing the qualified process or there is reason to doubt ability. The organization is responsible for maintaining continuity. | Maintain a per-welder, per-process continuity log reviewed monthly by the welding coordinator. | Qualification lapses after more than 6 months without the process | materialwelding.com |
| Certified Welding Inspector role AWS · AWS QC1 / D1.1 | A CWI is typically expected to review WPS, PQR and welder qualification records and to perform visual inspection of structural welds to the governing code (employer job postings; AWS certification scope not read). | A CWI (or CWI-supervised inspector) signs off weld inspection records for each module frame. | jobs.lever.co unverified | |
| Visual weld acceptance criteria AWS · AWS D1.1 visual inspection table | Visual acceptance table covers cracks, fusion, crater fill, profile, undersize, undercut, porosity and workmanship, with limits that vary by weld type and loading. Clause and table numbers differ by edition, and a secondary summary was the only page read, so numeric limits are not carried. | All welds are 100% visually inspected before coating; weld gauges used for size and profile. | ifactoryapp.com unverified | |
| Visual inspection before NDT AWS · AWS D1.1 | D1.1 calls for visual inspection of welds before other NDT or destructive testing on qualification test welds, to avoid unnecessary test cost. | Welds failing VT are repaired before any MT/UT is applied. | app.aws.org unverified | |
| NDT methods MT, PT, UT, RT AWS · AWS D1.1 | Surface methods (MT, PT) find surface cracks; UT and RT find internal flaws such as porosity and lack of fusion. D1.1 sets NDT acceptance criteria; specific sampling rates were not confirmed by any source read. | Fillet welds and CJP/PJP groove welds in critical corner connectors would get MT/UT per an inspection plan set by the engineer of record. | eziil.com | |
| Welder qualification test acceptance (RT) LANL · AWS D1.1 based procedure | LANL welder qualification document applies a D1.1 radiographic test for which no cracks are permitted (it also lists a separate ASME IX RT criterion). | Illustrates that crack indications are always rejected in qualification testing. | No cracks permitted | engstandards.lanl.gov |
| Snug-tight definition and install sequence Caltrans (citing RCSC) · RCSC Specification as applied in Caltrans BCM 55-1.03 | Every fastener in a joint is first brought to snug-tight, with plies in firm contact, before final tightening begins. Snug-tightening and final tightening both follow a systematic crisscross pattern. Snug-tight is a few hits of an impact wrench or the full effort of an ironworker with a spud wrench (university course notes citing RCSC 2000). | Corner connector bolts are snugged in a set sequence before final tensioning. | dot.ca.gov | |
| Pretensioning methods Caltrans (citing RCSC) · RCSC Specification as applied in Caltrans BCM 55-1.03 | Caltrans lists two standard methods (turn-of-nut, calibrated wrench) and two alternates (twist-off tension control, direct tension indicator); the RCSC combined method is also referenced. All fastener systems must pass pre-installation testing before being installed. | One method is chosen for the A325 corner connectors, with a pre-installation verification assembly logged per lot. | Frequency: Pre-installation test on not less than 3 bolts per diameter, length, grade and lot | dot.ca.gov |
| Turn-of-nut verification marks Caltrans (citing RCSC) · RCSC Table 8.1 | Nut is turned a prescribed amount from snug; a matchmark through the bolt tail should remain aligned with the start mark, otherwise the bolt may have turned and tension may be low. | Matchmark each bolt after snugging; inspector checks marks at final. | dot.ca.gov | |
| Direct tension indicator washers University course notes (citing AISC / RCSC) · ASTM F959 | Direct tension indicator washers have protrusions that flatten as the bolt is tightened; the remaining gap is measured with a feeler gage and the bolt is properly pretensioned when the gap reaches the specified size (course notes citing RCSC 2000 and AISC). Gage thickness and washer requirements were not confirmed. | DTIs give a visual inspection record of pretension on corner bolts. | user.eng.umd.edu | |
| Rotational capacity test for galvanized A325 Portland Bolt (citing ASTM F3125) · ASTM F3125 2019 | Rotational capacity testing is required for galvanized A325 assemblies with nut and washer; done by manufacturer or responsible party. Bolts longer than 12D exempt. | Request ROCAP reports per lot with the galvanized A325 bolt order and keep them in the lot file. | 120 ksi: 240 deg up to 4D, 360 deg over 4D to 8D, 420 deg over 8D to 12D | portlandbolt.com |
| Structural bolt lot sampling Montana DOT · Montana DOT MT 407-20 (references ASTM F3125) | MDT method for rotational-capacity testing of high-strength bolts defines a test as 3 bolt assemblies per grade, diameter, length and lot; an assembly fails on thread stripping, shear or torsion failure, or a nut that does not turn freely by hand. | Illustrates DOT-style lot testing that a receiving program could mirror. | 3 assemblies per grade/diameter/length/lot | ftp.mdt.mt.gov |
| Member tolerances in Code of Standard Practice AISC · AISC 303 | Mill tolerances come from ASTM A6; fabricators may heat or mechanically straighten out-of-tolerance material. COSP Section 6 tolerances apply to fabricator-induced camber. Where COSP is silent, contract documents must set a tolerance. Numeric values not confirmed from a readable page. | Module frame drawings should state tolerances for squareness, diagonals and length since COSP does not cover module assemblies. | aisc.org unverified | |
| Galvanizing thickness grades AGA · ASTM A123 Table 1 | Minimum average coating grades in micrometers by category and steel thickness are set in Table 1; only minimums, no maximum. | Structural shapes 100 um for 1/4 to under 5/8 in. steel; pipe and tubing 75 um for 1/8 in. and over. | Structural shapes: 45 (<1/16), 65 (1/16-<1/8), 75 (1/8-<1/4), 100 (1/4 and thicker); pipe/tubing 45 to 75 | galvanizeit.org |
| Galvanized coating appearance AGA · ASTM A123 | Finish continuous, smooth and uniform, free of uncoated areas, blisters, flux deposits and gross dross inclusions. | Visual check of each galvanized frame on receipt from galvanizer. | No uncoated areas, blisters, flux deposits | galvanizeit.org |
| Magnetic thickness gauge sampling AGA · ASTM A123 / ASTM E376 | Large articles: three sections, at least five readings each; average of section averages meets grade. Small articles: at least five readings. Calibrate on certified shims. | Receiving inspection takes five readings per section on frame members. | Specimen average no more than one grade below required | hotdipgalvanizing.com |
| Galvanizing repair AGA · ASTM A780 / A123 | Bare area 1 in. or less narrowest dimension; total repair per part limited to 1% of surface or 36 sq in per ton, whichever less. Zinc paint at least 65% zinc dust in dry film; surface cleaned to bright metal. | Weld burn-off and handling damage repaired per A780 and recorded. | 1 in. max narrow dimension; 1% or 36 in2/ton; 65% zinc | hotdipgalvanizing.com |
| HSS vent and drain holes AGA · ASTM A385 | Trapped cleaning solutions or rinse water can flash to steam and rupture the fabrication; vent holes belong at the highest point and drain holes at the lowest point as mounted for galvanizing. | Frame designer includes vent/drain holes in every closed HSS before galvanizing. | Up to 3600 psi pressure from trapped moisture flashing to steam | galvanizeit.org |
| Corner cracking in galvanized HSS AGA · ASTM A143 | Cracking risk from tight A500 corner radii (inside about 2T vs 3T preferred), thick walls, residual stress and end restraint; mitigate with larger radius, corner grinding, stress relief, or A1085. | Inspect HSS corners at member ends after galvanizing; specify radius limits when ordering HSS. | 3T inside radius preferred minimum | galvanizeit.org |
| DFT measurement for paint systems KTA / SSPC · SSPC-PA 2 | Spot = average of at least 3 readings in a 1.5 in. circle; area = 5 spots per 100 sq ft. Verify gauge accuracy at the start and end of each shift. No standard recalibration interval; one year is a typical starting point from gauge manufacturers. | Duplex coating DFT is checked on each frame with a verified gauge. | Default +/-20% range if single value specified; Level 3 default | kta.com |
| DFT gauge verification ASTM · ASTM D7091 | Practice covers verification of magnetic and eddy current gauge accuracy and reporting. | Gauge verification records kept per shift. | store.astm.org | |
| Pull-off adhesion of coatings ASTM · ASTM D4541-22 | Two protocols: test to fracture, or pass/fail at a defined load, on metal substrates. | Used in first-article coating validation of the duplex system. | dinmedia.de | |
| Hot work control Institutional (NFPA 51B) · NFPA 51B | Permit forms apply a 35 ft clearance radius and a minimum 30 minute post-work fire watch. | Shop welding/cutting under permit program. | 35 ft radius; 30 min fire watch | bates.edu |
| Equipment calibration records KTA · SSPC-PA 2 | No standard recalibration interval for gauges; one year is a typical starting point suggested by manufacturers, set by experience and environment. | Calibration register covers DFT gauges, torque wrenches, tension calibrator. | 1 year typical starting point | kta.com |
36 items
Precast concrete and grout
| Test or check | Requirement | Applied to a module | Criteria / frequency | Source |
|---|---|---|---|---|
| PCI plant certification program PCI · PCI MNL-116 (structural), MNL-117 (architectural), MNL-130 (GFRC) | Each certified plant writes its own Quality Systems Manual, which PCI reviews and approves before certification proceeds. Plants are audited by third-party engineers in two unannounced audits per year, with checks tailored to the plant's products. | The slab and wet-wall core should be produced by a plant certified for structural precast (Group C), so the plant QC system is independently audited. | Frequency: Two unannounced audits per year per plant | pci.org |
| PCI certification categories PCI · PCI plant certification groups A, B, C, G | Groups are A (architectural), B (bridge), C (commercial) and G (GFRC). Subcategories: A has AT, AD, AC, AB, AA; B has B1 (mild-steel reinforced, no prestressing), B2, B3, B4 (prestressed bridge items); C has C1 (conventionally reinforced), C2 (prestressed hollow-core and repetitively produced products), C3 (prestressed members with straight strands), C4 (deflected strands). MNL-116 governs AD and all B and C categories; MNL-117 governs AT, AC, AB, AA; MNL-130 governs G. | Mild-steel-reinforced slab and core castings would fall under C1; prestressed slabs under C2 to C4. Any GFRC cladding panels would need Group G. | pci.org | |
| Certification requirement in state DOT precast programs Indiana DOT · INDOT Certified Precast Producer Program (ITM 813) | INDOT's manual states ITM 813 requires a producer to be certified by ACPA, NPCA or PCI before becoming an INDOT Certified Precast Producer, to keep a written, plant-specific Quality Control Plan, and to submit a copy of each annual audit and its deficiency response to INDOT's Office of Materials Management. | Shows how an owner can require and track third-party plant audits; the same submittal approach can be offered to project owners and code officials. | Frequency: Annual audit submittal | in.gov |
| Common plant-audit deductions (NPCA program) NPCA · NPCA Quality Control Manual, Sections 1.1.3, 4.3, 5.1.3, 5.2.2, 5.3.3, 5.3.5 | The NPCA article says auditors check equipment calibration, strike-off plate use for the air pot density test, cylinder making per ASTM C31 (wet cast), C1758 (SCC) or C497 (dry cast), and pre-pour reinforcement inspection documented on all pieces. Two deductions in Section 5.3 (density testing errors) trigger automatic probation. | Gives a concrete picture of what a plant audit looks at: calibration records, cylinder practice, and pre-pour reinforcement inspection of each module slab. | Air meters calibrated every 90 days; equipment and batch scales calibrated each year; aggregate moisture burns weekly where probes are present, otherwise daily; ACI Concrete Field Testing Technician Grade 1 listed as an acceptable QC credential Frequency: Pre-pour reinforcement inspection on all pieces (Section 4.3) | precast.org |
| Fresh concrete sampling ASTM · ASTM C172 | ASTM C172 covers obtaining representative samples of fresh concrete as delivered to the project site for tests of compliance with specification quality requirements. INDOT's precast manual lists it (AASHTO R 60) as the sampling method. | Samples for each slab and core pour should be taken by this method so test results represent the batch cast into the module. | store.astm.org | |
| Slump test ASTM · ASTM C143 | INDOT's precast manual lists ASTM C143 (AASHTO T 119) as the slump method for precast producers. | Slump (or spread for SCC) is checked at batching to keep consistent workability around dense rebar and embeds. | in.gov | |
| Air content by pressure method ASTM · ASTM C231 | INDOT's precast manual lists ASTM C231 (AASHTO T 152) for pressure-method air content. NPCA audit guidance says air meters should be calibrated every 90 days. | Air content matters for freeze-thaw durability of exposed slab edges and for any exterior precast portions. | Air meter calibration every 90 days (NPCA) | precast.org |
| Unit weight and yield ASTM · ASTM C138 | INDOT's precast manual lists ASTM C138 (AASHTO T 121) for unit weight. NPCA audit guidance notes a strike-off plate must be used for the air pot density test. | Unit weight confirms normal-weight mix vs design assumed for slab self-weight and lifting calculations. | in.gov | |
| Concrete temperature ASTM · ASTM C1064 | ASTM C1064 covers determination of the temperature of freshly mixed hydraulic-cement concrete (ASTM store scope page). | Fresh and curing temperatures are recorded for each pour to support hot or cold weather controls and maturity-based stripping. | store.astm.org | |
| Making and curing cylinders ASTM / NPCA · ASTM C31; ASTM C1758 (SCC); ASTM C497 (dry cast) | The NPCA article says cylinders are made per ASTM C31 for wet cast, C1758 for self-consolidating concrete and C497 for dry cast. INDOT lists C31 (AASHTO T 23) for making and curing specimens. | Release and 28-day cylinders for slabs and cores should be field-cured alongside the units until stripping. | precast.org | |
| Compressive strength testing ASTM · ASTM C39 (AASHTO T 22) | INDOT's precast manual lists ASTM C39 (AASHTO T 22) for compressive strength and C42 (AASHTO T 24) for concrete cores. | Strength at stripping and at 28 days is verified by cylinders; cores per C42 are the fallback for suspect units. | in.gov | |
| Stripping and handling strength verification PCI / NPCA · PCI Bridge Design Manual, Section 3.2.4.4.1 | PCI Bridge Design Manual guidance for strand lifting loops requires concrete strength of at least 3,000 psi at the time of handling. The manual does not prescribe how the plant verifies this; field-cured cylinders or maturity data are the usual approaches. | Modules should not be stripped or lifted until cylinders or maturity data show the strength used in the lifting design. | Minimum 3,000 psi at handling for strand lifting loops (BDM) | pci.org |
| Maturity method ASTM · ASTM C1074 | ASTM C1074 provides a procedure for estimating concrete strength by the maturity method, with the maturity index expressed as temperature-time factor or equivalent age. It requires establishing the strength-maturity relationship of the mixture in the laboratory and recording the temperature history of the in-place concrete. A vendor FAQ lists formwork removal among the decisions maturity can support. | Temperature sensors in slabs and cores can support stripping decisions, after calibration for the specific mix. | store.astm.org | |
| Reinforcement tolerances ACI · ACI 117-10 | An ACI webinar slide (ASCC/ACI, 2023) lists reinforcement position for a 9 in. elevated slab as plus/minus 3/8 in. under ACI 117 Section 2.2.1, cover as minus 3/8 in. under Section 2.2.2 and spacing as plus/minus 3 in. under Section 2.2.5. The full tolerance table and the band for thinner members were not read. | A slab around 9 in. thick follows the 3/8 in. position tolerance per the slide; thinner slabs may fall in a different band, and precast plants often work to PCI tolerances instead. | Plus/minus 3/8 in. reinforcement position for a 9 in. slab (ACI 117-10 Section 2.2.1, per ACI webinar slide) | concrete.org |
| Precast tolerances PCI · PCI MNL-135; draft PCI 135 | PCI's 1993 committee report on product tolerances covers precast and prestressed product types including prison cell modules. PCI has since published MNL-135 and posted a draft PCI 135 standard for public comment (2024, 2025); final status of PCI 135 was not confirmed because PCI's draft pages were not retrievable. | Module slab thickness, squareness, embed and sleeve positions must be controlled to the tolerances that govern module-to-module fit. | pci.org unverified | |
| Pre-pour reinforcement inspection NPCA · NPCA QC Manual Section 4.3 | NPCA guidance says to perform the pre-pour inspection on all pieces and document it to meet the NPCA QC Manual (Section 4.3). | Each module slab and core is checked for cover, spacing, sleeve and embed placement before casting. | Frequency: All pieces | precast.org |
| Reinforcing steel grades ASTM · ASTM A615, A706 | ASTM store scope pages: A615 covers deformed and plain carbon-steel bars for concrete reinforcement; A706 covers low-alloy steel bars for applications needing restrictive mechanical properties and chemical composition or enhanced weldability. WisDOT SPV.0060 references A615 Grade 60 bar. | Bars welded to the steel frame or embeds should be A706 or follow a documented welding procedure. | store.astm.org | |
| Lifting loop design basis PCI · PCI Bridge Design Manual, Section 3.2.4.4.1 (4th ed., Ch. 3) | For conventional-strand lifting loops: factor of safety of 4, concrete at least 3,000 psi when handled, minimum 24 in. embedment per leg (hooked at 90 degrees if short), and shackle pin or hook diameter at least 4 times the strand diameter. | Principle carries over to module lifting: lifting hardware is sized with a factor of 4 on tested capacity at the concrete strength at stripping. | FS 4; 3,000 psi; 24 in. embedment; 100 psi bond stress assumed for safe working load of 6 in. hooked monostrand loops with 24 to under 36 in. embedment | pci.org |
| Mechanical splice classes ACI · ACI 318-19 Section 18.2.7 and 25.5.7 | Per a Structure magazine article on ACI 318-19: Type 1 splices develop at least 125 percent of bar yield strength (1.25 Ab fy); Type 2 meet Type 1 and also develop the specified tensile strength of the bar. Type 1 is restricted from locations where yielding is likely. | Module-to-module grouted sleeves carrying tension should be Type 2 or tested to full bar tensile strength. | Type 1: 1.25 fy; Type 2: also fu (per Structure magazine article summarizing ACI 318-19) | structuremag.org |
| ICC-ES AC133 mechanical splice criteria ICC-ES · AC133 | ICC-ES report ESR-4275 evaluates a mechanical splice system to AC133 (2nd Edition, March 2025), states compliance with ACI 318-19 25.5.7.1 and 18.2.7.1, requires special inspection under IBC Section 1705, and requires components fabricated under a quality control system with ICC-ES inspections. The AC133 text itself was not read. | ESR-4275 covers threaded splices, not grouted sleeves. Grouted sleeves would need their own current ICC-ES report to AC133; verify the report covers the specific grouted product. | icc-es.org | |
| Special inspection of splices ICC-ES · ESR-4275 Section 4.4 (IBC 1705) | Special inspector verifies bar embedment, coupler and rebar identification, field preparation of bar ends and assembly of the splice. | Field assembly of module connections should be inspected and documented by a special inspector. | icc-es.org | |
| Mechanical splice testing method ASTM · ASTM A1034 | ASTM A1034/A1034M-24 covers qualification requirements and test methods of mechanical splices for reinforcing bars (earlier editions were titled test methods). ASTM states code bodies specify test loads, cycles and temperatures. | Sleeve prototypes and sampled production splices can be tested under A1034 for tensile strength. | store.astm.org | |
| Splice sleeve overview ACI · ACI 439.3R | ACI 439.3R-07 is an ACI report on types of mechanical splices for reinforcing bars. Its abstract says mechanical splices transfer force without depending on the surrounding concrete and that manufacturer-supplied information was not independently verified by the committee. | Background reference for choosing sleeve type. | concrete.org | |
| Grouted coupler performance and QA (state DOT provision) Wisconsin DOT · SPV.0060 Grouted Bar Couplers | WisDOT SPV.0060 (written for bridge pier columns) requires an independent test report showing couplers develop 100 percent of Fu of the attached Grade 60 bar (90 ksi for A615). Grout must come from the coupler manufacturer and match the certified test report, and all sleeves must be completely filled. | Sets a clear model for the module sleeve submittal: independent tensile test report plus matched manufacturer grout. | 100% Fu = 90 ksi for Grade 60 A615 | wisconsindot.gov |
| Grouting procedure and temperature limits Wisconsin DOT · SPV.0060 Sections C.1 and C.2 | WisDOT SPV.0060: pump grout in from the lower port until it flows freely from the upper port, then cap the upper port first. Sleeve temperature must exceed 50 F at grouting and during curing, and sleeves are protected from vibration or shock until temporary bracing is removed. | Field grouting of module sleeves needs port-flow verification and winter heating. | Sleeve temperature above 50 F during placing and curing | wisconsindot.gov |
| Grout cube testing for sleeves Wisconsin DOT · SPV.0060; AASHTO T 106, ASTM C109, C942 | WisDOT SPV.0060: make four sets of three 2 inch grout cubes in brass molds per AASHTO T 106; test one set at a minimum of 24 hours (or to decide bracing release) and at 28 days, per ASTM C109 and C942. | Cubes made at each grouting session document grout strength before module bracing is released. | Four sets of 3 cubes of 2 in.; test at 24 h and 28 d | wisconsindot.gov |
| Grout strength and flow acceptance example Texas DOT · TxDOT Special Specification 4078, Structural Grout (2004) | Prepackaged non-shrink cementitious grout to ASTM C1107, with ASTM C109 2 in. cube strengths (Table 1), flow cone efflux time per ASTM C939, and set time and durability limits. Job sampling includes at least six 3 by 6 in. cylinders per bridge span. | Example of numeric grout acceptance that could be adapted to module sleeve grout; confirm against the sleeve maker's data. | 2,500 psi at 1 d; 4,000 at 3 d; 5,000 at 7 d; 5,800 at 28 d; 20 to 30 s flow cone efflux | utcdb.fiu.edu |
| Shear key and closure joint bond FHWA · FHWA TechNote on bond of field-cast grouts to precast (16081) | FHWA TechNote: bond depends on test method, substrate roughness and moisture. Exposed aggregate surfaces give higher bond, and a saturated surface dry condition is often specified, kept by wet burlap or ponding. | Module shear keys and closure pours should specify roughened (exposed aggregate or similar) surfaces and SSD prep before grouting. | fhwa.dot.gov | |
| Joint surface prep in sleeve grouting Wisconsin DOT · SPV.0060 Section C.2 | Joint surfaces are cleaned of laitance, dirt, grease and debris and must be saturated surface dry before the precast element is set. | Applies directly to horizontal module-to-module bearing joints. | wisconsindot.gov | |
| Non-destructive testing methods ACI / ASTM · ASTM C805; ASTM C597 | ASTM store scope pages: C805 covers determination of a rebound number of hardened concrete using a spring-driven steel hammer; C597 covers determination of the propagation velocity of longitudinal stress wave pulses through concrete. | Used to investigate suspect units for uniformity, followed by cores to confirm. | store.astm.org | |
| Core testing of suspect units ASTM · ASTM C42 | ASTM C42 covers obtaining, preparing and testing cores drilled from concrete for length, compressive strength or splitting tensile strength. | Fallback when cylinder results are low or unreliable. | store.astm.org | |
| Hollow-core specifics PCI · PCI Journal paper on maturity for zero-slump concrete (2004); PCI MNL-126 | A 2004 PCI Journal paper reports a hollow-core plant suspected zero-slump test cylinders were not reliable for release strength, and found the maturity method reliable for release strength and detensioning time. MNL-126 and camber tolerances were not read. | If hollow-core is used, release strength verification and camber control need hollow-core specific handling. | pci.org | |
| Crack and surface defect acceptance State DOT (Indiana) · INDOT precast inspection manual, Chapters 3 to 5 | INDOT's manual covers surface defects (form bleeding, honeycombing, bug holes), reinforcement defects (wall shadowing, insufficient cover) and cracks; a 0.01 in. crack is used as a pipe test criterion. | Pipe values do not transfer to modules, but the defect categories and visual inspection approach do. | Pipe-specific only (0.01 in. crack gauge); not applicable to slabs | in.gov |
| Durability testing ASTM · ASTM C666 | ASTM store scope: C666 determines resistance of concrete specimens to rapidly repeated freezing and thawing in the laboratory (Procedure A in water, Procedure B freezing in air). It is not intended to give a quantitative measure of service life. | Relevant mainly to exposed edges in freezing climates. | store.astm.org | |
| GFRC panel testing ASTM / PCI · ASTM C947, C1228, C1229; PCI MNL-130 | ASTM store scopes: C1228 covers preparing test coupons for plant-manufactured thin-section GFRC; C947 covers flexural strength of GFRC sections; C1229 covers fiber content of an uncured GFRC sample panel (wash-out). PCI's plant certification page says Group G (GFRC) is governed by MNL-130. | Only relevant if GFRC cladding panels are used in the module envelope. | store.astm.org | |
| Fire resistance ratings PCI · PCI MNL-124 | PCI's fire design page says MNL-124 offers a rational design approach, that calculated capacity must exceed load demand during a fire, that elements need enough mass to limit temperature rise on the unexposed side, and that the heat transmission endpoint depends on concrete type and thickness. The page shows an example thickness table for solid slabs and walls. | The precast core and slab thickness can be used to claim an hourly rating by calculation, though thickness values were not retrieved. | pci.org |
26 items
Structural and connection testing
| Test or check | Requirement | Applied to a module | Criteria / frequency | Source |
|---|---|---|---|---|
| Gravity, wind and seismic load criteria for module design ASCE/SEI · ASCE 7-22 | Minimum design loads for buildings include dead, live, wind and seismic combinations, and ASCE 7 is adopted by reference into the IBC. Structures are designed for strength and stiffness to provide stability and structural integrity. | Each stacked module group is designed as a building to the ASCE 7 load combinations of the adopting jurisdiction. | asce.org | |
| Seismic design category and response modification coefficients ASCE/SEI · ASCE 7-22 Ch. 11 and 12 | Seismic design category and the system R, Omega0 and Cd are taken from ASCE 7 Table 12.2-1 for the selected steel seismic force-resisting system; values were not read in this research. | Module frames must be classified as a listed system or qualified by testing (see FEMA P-695 type approach) before R values are claimed. | asce.org unverified | |
| Standard for off-site construction: planning, design, fabrication, assembly ICC and Modular Building Institute · ICC/MBI 1200-2021 | Covers planning, design, fabrication and assembly of off-site construction and distinguishes structural modular from nonstructural modular components. | Frames the factory QA program and the roles of designer, manufacturer and installer for the modules. | shop.iccsafe.org | |
| Inspection and regulatory compliance for off-site construction ICC and Modular Building Institute · ICC/MBI 1205-2021 | Standard title indicates inspection, approval and regulatory compliance for off-site construction; the page read gave no scope text beyond the title. | Basis for third-party factory inspection and site-completion inspection records. | shop.iccsafe.org unverified | |
| Cyclic racking test method for shear and lateral elements ASTM · ASTM E2126 | Covers quasi-static cyclic (reversed) tests of vertical lateral-force-resisting elements to evaluate shear stiffness, strength and ductility; defines three cyclic protocols and uses a monotonic test to set amplitudes. Applies to wood or metal framing with sheathing or other bracing. | Used as a reference protocol for racking tests of module wall and floor-diaphragm assemblies; applicability to steel module frames must be justified by the engineer. | store.astm.org | |
| Static racking practice for framed walls ASTM · ASTM E564 | A practice for determining shear stiffness and strength of a framed wall section on a rigid foundation; not intended to classify sheathing capacity. | Static racking reference for infill and wall panels within the module. | webstore.ansi.org unverified | |
| Relationship of E72, E564 and E2126 ASTM · ASTM E72 / E564 / E2126 | E2126-25 Note 2 states the monotonic test is not an equivalent alternative to the cyclic protocols or to the E72 or E564 procedures, so static and cyclic results are not interchangeable. | Test reports must state which standard and protocol was used. | store.astm.org | |
| Cyclic loading protocol for inter-module joints FEMA · FEMA 461 | A QUT numerical study of inter-module connections applied the FEMA 461 cyclic loading protocol in ABAQUS models. FEMA 461 itself was not read. | Candidate protocol for connection tests alongside ATC-24 and AISC 341 Chapter K. | pmc.ncbi.nlm.nih.gov | |
| AISC 341 Chapter K qualifying cyclic tests AISC · ANSI/AISC 341 Chapter K | Chapter K gives loading protocols and acceptance criteria for qualifying cyclic tests of seismic connections; details not read here. | Use for any moment or braced connection that is credited for seismic resistance. | aisc.org unverified | |
| Walking vibration serviceability of steel floors AISC · AISC Design Guide 11 (2nd ed., AISC 811-2016) | Walking-vibration serviceability often requires much larger steel members than strength, deflection or human comfort, even in quiet areas such as offices or residences (article on the second edition of Design Guide 11). Numeric acceleration limits were not confirmed from a page read. | Check module floor with precast diaphragm; concrete mass generally helps, but boundary flexibility between modules should be assessed. | ej.aisc.org | |
| Deflection limits for floors and roofs ICC · IBC Table 1604.3 | IBC Table 1604.3 sets live-load and total-load deflection limits as span ratios; values must be confirmed in the adopted edition (table text not readable in this research). | Applied to module floor beams and the precast diaphragm. | floridabuilding.org unverified | |
| General structural integrity and tie forces ASCE/SEI · ASCE 7-22 Section 1.4 | ASCE 7-22 sets basic requirements for strength and stiffness to provide structural stability and structural integrity. Tie-force provisions for specific building types were not confirmed. | Tie rods and shear keys between stacked modules should be shown to provide a continuous load path. | asce.org | |
| Progressive collapse alternative load path assessment GSA / DoD · UFC 4-023-03 | Alternate path analysis (notional removal of a column or module) is the common method for robustness assessment under UFC 4-023-03; the document itself was not readable in this research. | Module-loss scenarios (corner and interior) should be checked for stacked units. | stg.wbdg.org unverified | |
| Anchor design in concrete ACI · ACI 318-19 Chapter 17 | Chapter 17 governs design of cast-in anchors for tension and shear failure modes in concrete; not read here. | Foundation cast-in anchors for module hold-down. | concrete.org unverified | |
| Anchor bolt material specification ASTM · ASTM F1554 | Specification for anchor bolts (anchor rods) in three strength grades (36, 55, 105) and two thread classes; Grade 55 has weldable and impact supplements. | Material certification for cast-in anchors. | store.astm.org | |
| Anchor testing in concrete ASTM · ASTM E488 | Test methods for tensile and shear strength of post-installed and cast-in-place anchors in cracked or uncracked concrete under static, seismic, fatigue and shock loading; intended for laboratory use with product-specific standards. | Reference for proof or confirmatory tests of installed anchors if required. | store.astm.org | |
| Below-the-hook lifting device design ASME (design-tool vendor article) · ASME BTH-1 | BTH-1 gives structural and mechanical design criteria for B30.20 lifting devices using design categories and service classes, with design factors that vary by category and service class. Specific factors were not confirmed against the standard. | Spreader beams and lifting frames for module picks. | sdcverifier.com | |
| Below-the-hook devices safety and proof testing ASME (design-tool vendor article) · ASME B30.20 | B30.20 requires load testing by a qualified person before initial use (2021 edition revised the load test requirements). Proof load percentages were not confirmed. | Proof load test of lifting beams and lugs before first use. | sdcverifier.com | |
| Dynamic amplification in rigging design ISARC paper (DnV based) · DnV rigging approach | ISARC 2025 paper states the DnV criteria recommend load sharing between diagonal slings in a 4-point configuration of 2/3 to 1/3 with a 1.5 dynamic amplification factor. | Starting assumption for lifting analysis of modules, to be confirmed by the rigging engineer. | iaarc.org | |
| Road transport vibration of modules University of Melbourne et al. · Godbole et al. 2018 | Dynamic loads on a module depend on vehicle loading, centre of mass height, suspension setup and damping, evaluated by an acceleration response spectrum. | Transport design accelerations should come from measured spectra, not a single fixed factor. | findanexpert.unimelb.edu.au | |
| Module-scale damage during transport Engineering Structures literature · Road-test study (search summary) | Structural components generally resist transport loads but non-structural damage such as to gypsum walls is relatively common. | Inspect finishes and joints after delivery and record. | doaj.org unverified | |
| Grouted sleeve connector qualification ACI ITG · ACI ITG-5.1 / ITG-5.2 | A PCI Journal paper states ACI ITG-5.2 specifies a maximum allowable energy-dissipating bar tension strain of 0.85 times the bar uniform elongation strain; ITG documents not read directly. | Grouted sleeves between modules or to foundations need documented cyclic and tensile qualification. | pci.org | |
| Grouted connector tests by cyclic uniaxial loading PCI Journal · Aragon, Kurama, Meinheit 2017 | Six bar specimens in tapered grouted connectors were cycled uniaxially; five fractured ductilely without pullout and one pulled out. | Shows the failure-mode check (bar fracture before pullout) to require in sleeve acceptance. | pci.org | |
| Inter-module connection pull-out and subassembly tests PolyU · Han et al. 2023 | Five pull-out tests and five lateral subassembly tests; yielding of the end or anchoring plate preferred over bolt failure; premature beam-to-column weld fracture was the main failure mode. | Weld quality control at beam-column corners is a hold point. | research.polyu.edu.hk | |
| Post-tensioned inter-module connection University of Seoul · Load-carrying mechanism study | A post-tensioned inter-module connection specimen showed similar lateral load resistance and deformation capacity to a bolted-connection specimen (abstract). | Supports use of post-tensioned tie rods. | pure.uos.ac.kr | |
| Module-loss collapse capacity Western Sydney University · Alembagheri et al. 2020 | Macro-model FE analysis with rigid volumetric modules and nonlinear axial and shear connection springs under sudden module loss; authors report considerable collapse resisting capacity. | Connection stiffness and strength drive robustness for stacked modules. | researchers.westernsydney.edu.au |
Studies
| Study | Finding | Limits | Source |
|---|---|---|---|
| Seismic mitigation of steel modular building structures through innovative inter-modular connections Sendanayake, Thambiratnam, Perera, Chan, Aghdamy (QUT) 2019 | Numerical ABAQUS study; weld at column to column plate was the ultimate failure mode and bolts did not reach critical stress. C1 capacity 250 to 280 kN; ductility ratio 2.06 for baseline versus 53.25 for best rubber-layer variant. | Finite element only, validated against one published test. | pmc.ncbi.nlm.nih.gov |
| Insights into the cyclic behaviour of novel hybrid inter-module joints under lateral load Tsavdaridis and Corfar (City, University of London) 2024 | Three bi-axial cyclic tests on meso-scale joints with bolts and rubber bearings; stiffeners and larger bolts improved failure mode and stiffness degradation. Eurocode 3 classed them semi-rigid, partial strength. | Conference abstract only; no capacities given. | openaccess.city.ac.uk |
| Experimental investigation on bolted inter-module connections and subassemblies of steel modular frames Han, Wang, He, Hu, Chan, Chung 2023 | Five pull-out and five lateral subassembly tests; subassemblies failed by premature beam-to-column weld fracture. | Abstract only; no load values read. | research.polyu.edu.hk |
| Dynamic loading on a prefabricated modular unit of a building during road transportation Godbole, Lam, Mafas, Fernando, Gad, Hashemi 2018 | Dynamic load depends on load, centre of mass, suspension and damping; analysed with an acceleration response spectrum. | Abstract truncated; no numbers read. | findanexpert.unimelb.edu.au |
| A Type III grouted seismic connector for precast concrete structures Aragon, Kurama, Meinheit 2017 | Of six cyclically tested bar specimens, five fractured ductilely without pullout and one pulled out with slightly lower grout strength. | Abstract only; bar sizes and amplitudes not read. | pci.org |
| Collapse capacity of modular steel buildings subject to module loss scenarios Alembagheri, Sharafi, Hajirezaei, Samali 2020 | Authors concluded modular buildings possess considerable collapse resisting capacity and higher robustness than conventional buildings. | Numerical; no quantitative results in abstract. | researchers.westernsydney.edu.au |
| Shake table tests of a 0.25-scale three-storey stacked modular steel structure with sliders University of Auckland not confirmed | Record describes a 0.25-scale three-storey stacked modular steel structure with sliding bearings under biaxial loading, with a 2.5 percent drift figure mentioned; results not read. | Scaled model; keyword-level record only, no results or year confirmed. | researchspace.auckland.ac.nz |
| Full-scale steel modular test building on NHERI UC San Diego shake table UC San Diego NHERI and Utah team 2022 | Full-scale steel-framed building with buckling restrained braces and special moment frames was shaken in April and May 2022. | Building was a framed test structure (MTB2), not stacked housing modules; dates per DesignSafe news page, which could not be fetched directly. | designsafe-ci.org |
| Progressive collapse of MiC structures and the role of inter-module connections He, Chan, Chung (PolyU) 2021 | Inter-module connection types affect beam-column joint properties; the rigid beam-column joint assumption may lead to nonconservative evaluation. | Abstract only; J. Constr. Steel Res. 185, 106823. | research.polyu.edu.hk |
| Anti-collapse behavior of modular steel buildings with corrugated-plate connections (J. Constr. Steel Res. 193, 107279) PolyU (authors not captured) 2022 | Abstract reports dynamic amplification factors at the collapse limit state of 1.20 to 1.29 for interior and 1.27 to 1.50 for corner module removal. | Abstract only; collapse-limit-state DAF for module removal, not a lifting DAF. | research.polyu.edu.hk |
| Rigging validation for four-pick-point module lifts Kheir, Han, Bagchi (Concordia University) 2025 | States that DnV criteria recommend 2/3 to 1/3 sling load sharing in a 4-point configuration with a 1.5 dynamic amplification factor; notes modules in heavy-lift practice can weigh up to 160 tons and have up to 16 lifting points. | Read in full text, but the DnV approach is cited secondhand; industrial heavy-lift context, not housing modules. | iaarc.org |
43 items
Envelope and environmental performance
| Test or check | Requirement | Applied to a module | Criteria / frequency | Source |
|---|---|---|---|---|
| Whole-building air leakage by fan pressurization ASTM · ASTM E779 | Measures air leakage through a building envelope under controlled pressurization and depressurization with a blower door. Intended for small indoor-outdoor temperature differences and low wind; it quantifies airtightness, not natural infiltration. | Run on a completed unit in the factory (before finishes close access) and again on the assembled building on site. Factory results give a per-module baseline. | store.astm.org | |
| Blower door test, orifice method ASTM · ASTM E1827 | Two techniques for measuring air leakage through a building envelope, both using an orifice blower door, under pressurization or depressurization. Intended for small indoor-outdoor temperature differences and low wind. Does not measure air change rate under normal conditions (that is ASTM E741). | Accepted by the IECC as a blower door test method alongside ASTM E779 and ANSI/RESNET/ICC 380; used as the practical factory and site method for dwelling-unit modules. | store.astm.org | |
| IECC residential air leakage limit ICC · IECC R402.4.1.2 | 2021 IECC R402.4.1.2 requires the building or dwelling unit to be tested for air leakage; under any compliance path the maximum is 5.0 air changes per hour or 0.28 cfm per ft2 of dwelling unit enclosure area, tested per ANSI/RESNET/ICC 380, ASTM E779 or ASTM E1827 and reported at 50 Pa. R402.4.1.3 sets 5.0 ACH50 in climate zones 0-2 and 3.0 ACH50 in zones 3-8 where complying with the prescriptive path. Testing is done after all envelope penetrations are sealed, and by an approved third party where the code official requires it. | Acceptance test on every dwelling unit on site after set and sealing; factory pre-test lowers the risk of failure. | 2021 IECC text as reproduced by Yakima County: 5.0 ACH50 (zones 0-2) and 3.0 ACH50 (zones 3-8) under R402.4.1.3; 0.28 cfm/ft2 of enclosure area alternative; exception of 0.30 cfm/ft2 for attached dwelling units or units 1,500 ft2 or smaller. 2024 edition values not confirmed. Check the adopted edition and local amendments. Frequency: Each building or dwelling unit, after envelope penetrations are sealed | yakimacounty.us |
| ANSI/RESNET/ICC 380 airtightness procedure RESNET · ANSI/RESNET/ICC 380 | Named in IECC R402.4.1.2 (2021) as one of three accepted procedures for the building or dwelling unit air leakage test, with ASTM E779 and ASTM E1827, reported at 50 Pa. | Test procedure option for each unit; the code official may require an approved third party to conduct it. | yakimacounty.us | |
| Passive House airtightness Passive House Institute · Passive House Building Criteria | Airtightness is a core principle and a test is part of final certification evidence. The page read gives no n50 value for new Passive House buildings; the numbers are in the Building Criteria document. | Design target for the high-performance product tier; tested at factory and again after on-site assembly. | EnerPHit unit: qE50 <= 1.0 m3/(h m2) (as stated on the page). New-build n50 value not read. Frequency: Final airtightness test required for certification | passivehouse.com |
| Air barrier system design and continuity Building Science Corporation · BSD-014 | Describes the air barrier as an assembly of materials, joints and penetrations; continuity is called the most important and most difficult requirement. Suggests about 2.0 L/s m2 at 75 Pa for a whole building and 0.2 L/s m2 for components as targets. | Informs inter-module joint and penetration detailing; verified by factory and site blower door and smoke or thermography checks. | Suggested targets: about 0.2 L/s m2 at 75 Pa (components), about 2.0 L/s m2 at 75 Pa (whole building). | buildingscience.com |
| Air barrier assembly leakage ASTM · ASTM E2357 | Laboratory test method for the air leakage rate of air barrier assemblies used in building enclosures. Measures a representative assembly before and after specified conditioning cycles and assigns a rating; may also be applied to site mockups. | Design-stage mock-up of the wall, floor and inter-module joint assembly. | store.astm.org | |
| Water penetration, laboratory ASTM · ASTM E331 | Determines resistance of exterior windows, curtain walls, skylights and doors to water penetration when water is applied to the outdoor face and exposed edges while the outdoor face is at a higher static air pressure than the indoor face. Addresses water penetration through a manufactured assembly; the scope does not set a test pressure or duration (the specifier chooses the pressure). Does not address effects on sealants or on insulating or laminated glass. | Design prototype for window-in-steel-opening and rainscreen mock-ups; repeated if details change. | store.astm.org | |
| Water penetration, field ASTM · ASTM E1105 | Field test of installed exterior windows, skylights, doors and curtain walls for water penetration under a uniform or cyclic static air pressure difference with water applied to the outdoor face. Procedure A holds constant pressure for 15 minutes; Procedure B uses five-minute cycles each followed by one minute at zero pressure. Can also check leakage at joints between the assembly and adjacent construction. Test pressure values are not stated in the sources read. | Sample units on site after module set and joint sealing, and as a forensic check on reported leaks. | constructionspecifier.com | |
| Hose-stream field water test, window installation FGIA (formerly AAMA) · AAMA 501.2 | Quality assurance and diagnostic field check that uses a calibrated nozzle to direct a water stream onto installed storefront, curtain wall and sloped glazing components intended to be watertight. Qualitative; not appropriate for windows, doors or operable vents glazed into systems that carry an AAMA performance class rating. | Spot check of fixed glazing and joint seals on site; not a rated pass or fail test of window performance. | constructionspecifier.com | |
| Field water test, windows FGIA (formerly AAMA) · AAMA 502 / 503 | AAMA 502 is a voluntary specification for field verification of air leakage (ASTM E783) and water penetration (ASTM E1105) of newly installed windows and doors, using a sealed chamber on the specimen. AAMA 503 is the counterpart for curtain walls, storefronts and sloped glazing. Test pressures are not stated in the sources read. | Site acceptance on sample windows. | constructionspecifier.com | |
| Rain control design principles Building Science Corporation · BSD-013 | Screened-drained walls assume some water passes the cladding and design drainage behind it; the gap serves as ventilation space and capillary break; windows, decks and terminations interrupt the drainage plane and need flashing and drains. | Design review item for rainscreen panels, thermally broken rails and window-opening flashing. | buildingscience.com | |
| Ventilated cladding field and modelling review Building Science Corporation · RR-0907 | Report on ventilated wall claddings and hygrothermal modelling. The abstract says earlier software had limited ability to model ventilated claddings, that WUFI 4.1 can add moisture and heat sources and sinks to simulate airflow effects, and that where wetting cannot be kept acceptable, safe storage and drying become critical. | Supports modelling of cavity depth and venting at rainscreen panels. | buildingscience.com | |
| Inter-module joint water and air sealing test Project-specific · ASTM E331 / E1105 adapted | Project-specific practice. No published standard for module-to-module joints was found. ASTM E1105 can check leakage at joints between an assembly and adjacent construction, so the practice is to mock up the joint and run E331 (lab) or E1105 (field) style tests. | Design prototype joint mock-up, then field spray tests on the first installed modules. | store.astm.org | |
| North American Fenestration Standard FGIA / WDMA / CSA · AAMA/WDMA/CSA 101/I.S.2/A440 | Harmonized standard for windows, doors, tubular daylight devices and unit skylights, combining AAMA 101, WDMA I.S.2 and CSA A440. Determines performance grade (PG) and design pressure (DP) with air leakage, water penetration and structural (uniform load) tests. Does not cover energy ratings such as U-factor, SHGC or condensation resistance. | Window supplier provides a rated product; confirm label and PG against project design pressure. | constructioncanada.net | |
| NFRC U-factor and SHGC ratings NFRC · NFRC 100 / 200 | NFRC 100 is a computer simulation procedure (LBNL WINDOW and THERM) for product U-factor at winter conditions of 70 F indoors and 0 F outdoors, typically paired with the NFRC 102 test to validate results. NFRC 200 uses the same tools for solar heat gain coefficient and visible transmittance at summer conditions (75 F indoors, 90 F outdoors). | Window supplier certified label; required input to energy compliance. | w3inte.intertek-france.com | |
| Insulating glass unit durability ASTM · ASTM E2190 | Specification giving performance requirements and an evaluation method for preassembled, permanently sealed insulating glass units (double or triple glazed). Qualification depends on frost/dew point and absence of fog after specified test durations; argon-filled units must keep their argon content. Does not cover spandrel-coated glass. | Required of the glazing supplier for the triple-pane units. | store.astm.org | |
| IGCC / IGMA insulating glass certification IGCC / IGMA · IGCC certification program | IGCC/IGMA certification program (administered by FGIA) certifies insulating glass to ASTM E2190. The page refers to a testing phase and an auditing process; frequency is not stated. | Supplier qualification for the triple-pane units. | fgiaonline.org | |
| Glass load resistance ASTM · ASTM E1300 | Practice for determining the load resistance of glass, including glass in sealed insulating glass units, under uniform lateral loads for a specified probability of breakage. Covers vertical and sloped glazing with total design load of 15 kPa or less; IG units only with four-sided support. | Design check for triple-pane glass sizes against project wind loads. | store.astm.org | |
| Impact resistance of glazing ASTM · ASTM E1886 / E1996 | ASTM E1886 tests exterior windows, curtain walls, doors and impact protective systems struck by missiles and then subjected to cyclic static pressure differentials, to assess whether they stay unbreached in a windstorm. ASTM E1996 is the specification for such components in hurricane-prone regions and supplies the information needed to run E1886. Garage and rolling doors are excluded. | Only where project sites require it; type test. | store.astm.org | |
| Structural performance by uniform static air pressure ASTM · ASTM E330 | Determines structural performance of exterior windows, doors, skylights and curtain walls under uniform static air pressure differences in a test chamber, which creates uniformly distributed test loads. Procedure A is used when a load-deflection curve is not required; Procedure B when it is. | Design prototype of the window-in-steel-opening and rainscreen panel fixings. | store.astm.org | |
| Air leakage of windows, laboratory ASTM · ASTM E283 | Laboratory test method measuring air leakage through exterior windows, skylights, curtain walls and doors at a specified pressure difference, with equal temperature and humidity on both sides. Measures the assembly itself, not its installation; field testing of installed units falls under E783. | Part of NAFS test suite for the window supplier. | store.astm.org | |
| Guarded hot box thermal test ASTM · ASTM C1363 | Sets principles of hot box apparatus design and minimum requirements for steady-state thermal performance of building assemblies; covers large homogeneous or non-homogeneous specimens; steady state only; fenestration is excluded and handled by C1199 and E1423. | Design prototype of one typical wall section to calibrate thermal models. | Standard sets no pass value; results are compared to design. | store.astm.org |
| Thermal bridging catalogue and method BC Hydro / Morrison Hershfield · Building Envelope Thermal Bridging Guide | Describes the BETA method, clear field U-value, linear (psi) and point (chi) transmittance. States that details usually disregarded can cause underestimation of 20% to 70% of heat flow through walls. Catalogue includes steel stud construction and was calculated with 3D modelling. | Design stage: model rail attachments, window interfaces, floor edge and inter-module joints to produce psi-values. | Underestimation of 20% to 70% of heat flow if details are ignored (as stated). | bchydro.com |
| Linear thermal transmittance (psi-value) calculation BC Hydro / Morrison Hershfield · BETB Guide section 3.3 | Psi is found by comparing heat flow through an interface detail with and without the thermal bridge; the difference is expressed per length. | Applied to each repeating junction in the module (rail brackets, slab edge, window jamb). | bchydro.com | |
| Numerical thermal bridge calculation ISO · ISO 10211 | ISO 10211:2017 sets specifications for 3D and 2D geometrical models of a thermal bridge for numerical calculation of heat flows, to assess overall heat loss, and minimum surface temperatures, to assess surface condensation risk. It can also derive linear and point thermal transmittances. | Design verification using 2D/3D models; THERM from LBNL is a common 2D tool. | sis.se | |
| Effective R-value of steel-framed walls ASHRAE · ASHRAE 90.1 Appendix A | ASHRAE 90.1 Appendix A provides assembly U-factors for steel-framed walls. Addendum aw to 90.1-2022 states that Table A9.2-2 gives effective R-values for the framing and cavity insulation layer, derived from tested walls with about a 10 percent framing factor, and proposes a psi-factor approach to better capture thermal bridging. | Used for compliance paths if modelling is not performed. | ashrae.org | |
| Infrared thermography of building envelopes ASTM / ISO · ASTM C1060 / ISO 6781 (ISO 6781:1983 withdrawn 2023, replaced by ISO 6781-1:2023) | ASTM C1060 covers qualitative infrared thermographic inspection of wood- or metal-framed walls, ceilings, roofs and floors with insulation between framing, to find cavities with missing or inadequate insulation. Findings need independent validation such as visual inspection or in-situ R-value measurement. The standard applies only to frame construction. ISO 6781:1983 specified a qualitative infrared method for thermal irregularities and did not determine insulation level or air tightness. | Factory check of completed modules and site check of module joints. | store.astm.org | |
| Condensation resistance of windows FGIA (formerly AAMA) · AAMA 1503 | AAMA 1503 measures the thermal characteristics of windows, doors and glazed exterior wall sections under steady-state conditions, yielding thermal transmittance (U-value), air infiltration rate and Condensation Resistance Factor (CRF), using a guarded hot box. | Supplier data to assess frost and condensation risk at the steel-framed openings. | law.resource.org | |
| Hygrothermal simulation ASHRAE / Fraunhofer · ASHRAE 160 / WUFI | ANSI/ASHRAE 160 sets performance-based criteria for moisture design analysis of buildings, with a mold index and an indoor RH cap of 70 percent or less in the 2016 edition. WUFI-ORNL/IBP is a transient heat and moisture simulation model that handles vapour diffusion and wind-driven rain (described at osti.gov/biblio/788530). | Design stage for every wall and roof build-up in each climate zone. | shop.iccsafe.org | |
| Water vapour permeance ASTM · ASTM E96 | Gravimetric determination of water vapor transmission rate of paper, plastic films, sheet materials, coatings, foams, fiberboards, gypsum products and wood products by the desiccant method or the water method, which can give different results. | Material qualification for membranes and insulation used in rainscreen assemblies. | store.astm.org | |
| Fire resistance of building elements ASTM · ASTM E119 | Fire-resistance test methods for building assemblies, including load-bearing and other walls and partitions, columns, beams, slabs, and floor and roof assemblies. Results compare performance under specified fire conditions. | Relevant to precast floor and steel frame assemblies; use existing listings where available. | store.astm.org | |
| Surface burning characteristics ASTM · ASTM E84 | Ten-minute fire-test response method for comparative surface burning of materials on exposed walls and ceilings; reports a flame spread index and a smoke developed index. Does not measure heat transmission. | Material qualification for panels and insulation. | store.astm.org | |
| Exterior wall fire propagation NFPA · NFPA 285 | NFPA 285 is the fire test that exterior wall assemblies with a combustible water-resistive barrier must pass under California Building Code 1402.5, as cited by the San Diego bulletin read. The wall must be constructed as tested, with only narrow permitted variations. Code triggers vary by edition and jurisdiction. | Design prototype or an existing listing/approval letter for the exact rainscreen build-up. | sandiego.gov | |
| Airborne sound transmission ASTM · ASTM E90 / E413 | ASTM E90 is the laboratory measurement of airborne sound transmission loss of building partitions and elements (walls, floor-ceiling assemblies, doors, windows). ASTM E413 calculates single-number ratings such as STC from one-third octave band data. | Design prototype of demising wall and floor assemblies. | store.astm.org | |
| Impact sound transmission ASTM · ASTM E492 / E989 | ASTM E492 is the laboratory measurement of impact sound through floor-ceiling assemblies using the standard tapping machine. ASTM E989 calculates the single-number IIC rating (FIIC for field tests under E1007). | Design prototype of precast floor with finish. | store.astm.org | |
| IBC dwelling-unit sound separation ICC · IBC section 1206 (numbering varies) | California Building Code section 1206 (the page read is the 2025 CBC, the state adoption of the IBC) requires walls, partitions and floor-ceiling assemblies separating dwelling units and sleeping units to have STC of at least 50 per ASTM E90, or NNIC of at least 45 if field tested per ASTM E336. Floor-ceiling assemblies need IIC of at least 50 per ASTM E492, or NISR of at least 45 if field tested per ASTM E1007. Engineering analysis by a registered design professional is an allowed alternative. Section number and field-metric names vary by IBC edition. | Field test of sample unit pairs on site. | CBC 1206 text read: STC 50 lab / NNIC 45 field (airborne); IIC 50 lab / NISR 45 field (impact). Confirm against the adopted IBC edition. | gocodebook.com |
| Coating performance for metal FGIA (formerly AAMA) · AAMA 2603 / 2604 / 2605 | AAMA 2603, 2604 and 2605 are voluntary specifications with performance requirements and test procedures for pigmented organic coatings on aluminum extrusions and panels: 2603 base level, 2604 high performance, 2605 superior performing. They address film integrity, outdoor durability and appearance. Last updated 2022. | Supplier certificate for coated aluminum extrusions and panels (these specifications are written for aluminum, not coated steel). | fgiaonline.org | |
| Salt spray corrosion ASTM · ASTM B117 | Practice covering the apparatus, procedure and conditions needed to create and maintain a salt spray (fog) test environment. It does not specify test specimens or exposure periods for a given product, or how to interpret results. | Coating and fastener qualification. | store.astm.org | |
| Accelerated weathering ASTM · ASTM G154 / G155 | ASTM G154 covers operating fluorescent UV lamp and water apparatus; ASTM G155 covers xenon arc lamp and water apparatus. Both reproduce sunlight and moisture weathering effects but define only how to obtain and control exposure conditions; they must be paired with a method that sets exposure and evaluation. G155 excludes corrosion testing of bare metals. | Material qualification for finish panels. | store.astm.org | |
| GFRC panel practice PCI · PCI MNL-128 | PCI MNL-128 is the Recommended Practice for Glass Fiber Reinforced Concrete Panels. A California DSA interpretation states that California Building Code section 1903A.3 requires GFRC to comply with it. PCI also publishes a newer specification, PCI 128. | Applies if GFRC finish panels are used. | dgs.ca.gov | |
| Building commissioning process ASHRAE · ASHRAE Guideline 0 / 1.1 | ASHRAE Guideline 1.1 sets technical requirements for applying the commissioning process described in Guideline 0 to HVAC&R systems, to verify they meet the owner's project requirements; it includes sample forms and checklists. | Post-installation functional checks of ventilation and heating systems after module set. | csemag.com | |
| Building America Solution Center guidance US DOE · Building America | DOE program website providing guidance on high-performance construction topics including air sealing and insulation, with research reports, how-to guides and checklists (read via the Enterprise Community Partners description of the DOE resource). | Reference for best practice. | enterprisecommunity.org |
29 items
Factory process, MEP and shipping
| Test or check | Requirement | Applied to a module | Criteria / frequency | Source |
|---|---|---|---|---|
| DWV water test ICC · IRC P2503.5.1 (2021 edition) | Rough DWV piping is tested by water, or by air or vacuum where permitted, applied to the whole system or in sections. For the water test each section is filled to at least 10 feet above the highest fitting connection in that section, held for 15 minutes, and must prove leak free by visual inspection. The 2015 IRC had reduced the head to 5 feet and the 2021 IRC restored 10 feet, matching the 10 ft in the International Plumbing Code. | Run on each module's rough plumbing in the factory before drywall closes the chases. | 10 ft head; 15 minutes | iccsafe.org |
| DWV air or vacuum test option ICC · IRC P2503.5.1 (2021 edition) | The 2021 IRC permits an air test for non-plastic DWV piping and a vacuum test for plastic piping. Air test: 5 psi (or 10 in. Hg) held 15 minutes without added air. Vacuum test: -5 psi (or -10 in. Hg) held 15 minutes. Positive air pressure testing of plastic pipe is not permitted under the 2021 IRC. | Factory may choose air or vacuum testing where the adopted code edition permits it, to avoid wetting framing. | Air 5 psi, 15 minutes (non-plastic); vacuum -5 psi, 15 minutes (plastic) | iccsafe.org |
| Water supply system test ICC · IRC P2503.7 (verify edition text) | Supply piping is proved tight under water pressure not less than the system working pressure, held at least 15 minutes, or by an air test at 50 psi where allowed. This comes from a secondary study guide; the 1.5x working-pressure figure is not supported by IRC text and is not claimed. | Each module's supply manifold and risers are pressure tested before insulation and drywall, and the result is logged on the traveler. | open-exam-prep.com unverified | |
| Electrical installation compliance NFPA · NFPA 70 (NEC) Article 110 and Chapter 4 (verify) | NEC governs installation, listing and labeling of equipment. Continuity, polarity, GFCI and AFCI device function are standard checks by inspectors, but the NEC does not prescribe a factory test sequence. | Factory QA uses a documented continuity, polarity and device-function check per circuit before covering walls. | nfpa.org unverified | |
| GFCI and AFCI protection NFPA / UL · NEC 210.8 and 210.12 | GFCI protection is required for dwelling-unit receptacles in listed locations such as bathrooms, garages, outdoors, basements, kitchens, laundry areas and within 6 ft of sinks. AFCI protection is required on 15A and 20A, 120V branch circuits serving most living areas, bedrooms, kitchens, closets, hallways and laundry areas, but not bathrooms, garages or outdoors. Exact lists vary by NEC edition. | Each module's protected circuits are tested with a listed tester and the device test buttons, and the results are logged. | ecmweb.com | |
| Electrical equipment maintenance testing NFPA · NFPA 70B | NFPA 70B covers maintenance of in-service electrical equipment, including insulation resistance testing practice. It is not a residential new-build factory requirement. | Useful as a reference for maintaining plant test equipment and panels, not as the module acceptance standard. | nfpa.org unverified | |
| Electrical safety in the workplace NFPA · NFPA 70E | NFPA 70E addresses worker safety when testing or working on energized electrical equipment. It governs how factory electricians do live testing, not what the module must pass. | Applies to plant procedures for energized checks, lockout and PPE during module power-up tests. | nfpa.org unverified | |
| Duct leakage limits ICC · IRC N1103.3.6 / IECC R403.3.6 (2021; text read is Washington State amended) | Rough-in test: total leakage at or below 4.0 cfm per 100 sq ft of conditioned floor area at 25 Pa, with registers sealed (3.0 if the air handler is not yet installed). Post-construction: 4.0 cfm per 100 sq ft, total or to outdoors. Where all ducts and air handlers are entirely inside the thermal envelope: 8.0 cfm per 100 sq ft. Values come from the Washington State amended text; the base code and other states' amendments may differ. | Duct systems in factory modules are tested at rough-in before enclosure; limits depend on the adopted edition. | 4.0 cfm/100 sq ft at 25 Pa (3.0 if air handler not installed); 8.0 if all ducts inside envelope (Washington State text) | lawfilesext.leg.wa.gov |
| Duct leakage test method ASTM / RESNET · ANSI/RESNET/ICC 380 or ASTM E1554 (IRC N1103.3.5 / IECC R403.3.5, 2021) | Ducts are pressure tested per ANSI/RESNET/ICC 380 or ASTM E1554, at a pressure differential of 25 Pa, either at rough-in or post-construction, with registers taped or sealed during the test. | Factory technicians seal registers and pressurize ducts to the specified test pressure. | yakimacounty.us | |
| Insulation installation grading RESNET · ANSI/RESNET/ICC 301 Appendix A (Grade I, II, III) | Installed cavity insulation is rated Grade I, II or III, or uninsulated, using inspection procedures equivalent to RESNET Appendix A. Insulation confirmed present but not fully inspected is modeled as Grade III and recorded as not inspected. | A factory inspector grades each wall, floor and ceiling cavity before drywall, with photos on the traveler. | Grade III if present but not inspected | resnet.us |
| Thermographic inspection limits RESNET · ANSI/RESNET/ICC 301-2014 Addendum F-2018 | Thermography may be used to confirm an assembly is insulated and achieves Grade II when performed by an ASNT NDT Level III or a licensed engineer, or by a person working under their direction. It must not be used to establish Grade I. | Infrared scans of finished modules can support QA but do not replace the visual Grade I inspection before cover. | resnet.us | |
| Thermal bypass inspection checklist ENERGY STAR / EPA · ENERGY STAR Single-Family New Homes National Rater Field Checklist (Rev. 14; Versions 3.1, 3.2, 3.3) | The current checklist requires all insulation to achieve Grade I per ANSI/RESNET/ICC 301 (alternatives in footnote 5), and a complete, fully aligned air barrier at each insulated ceiling, wall and floor location. Use the current ENERGY STAR revision for exact items. | Factory walks the checklist at insulation hold point, since many bypass areas are covered once drywall goes on. | energystar.gov | |
| Air barrier and envelope air leakage ICC · IRC R402.4.1.2 (2012 edition text read; later editions and amendments differ) | The energy code requires a blower door test of the dwelling at or below a climate-zone limit. In the 2012 IRC text read, the limit is 5 air changes per hour at 50 Pa in Climate Zones 1-2 and 3 ACH50 in Zones 3-8. | Modules are sealed in factory; envelope test is done on site after set and joint sealing because module-to-module joints are part of the envelope. | 5 ACH50 (CZ 1-2); 3 ACH50 (CZ 3-8), 2012 IRC as adopted by Pima County | pima.gov |
| Smoke alarms ICC / UL · IRC R314; UL 217 | Alarms are listed to UL 217 and located in each sleeping room, outside each sleeping area, and on each additional story. Where more than one is required they are interconnected so actuation of one sounds all in the unit; listed wireless alarms may substitute for physical interconnection. Source is ICC code-change proposal text, not adopted-code text. | Factory installs and tests alarms and interconnect wiring per module, then re-verifies after set. | iccsafe.org unverified | |
| Carbon monoxide alarms ICC / UL · IRC R315; UL 2034 | In new construction, CO alarms are required outside each sleeping area in dwelling units that contain a fuel-fired appliance or have an attached garage opening into the unit. Alarms are listed to UL 2034; combination CO/smoke alarms are listed to UL 2034 and UL 217. Source is ICC code-change proposal text, not adopted-code text. | All-electric modules may be exempt; confirm by adopted code and local amendments. | iccsafe.org unverified | |
| Fire blocking and draftstopping ICC · IRC R302.11 | Fireblocking is required to cut off concealed draft openings: in stud wall concealed spaces at ceiling and floor levels and horizontally at intervals not exceeding 10 ft, at soffits and drop ceilings, between stair stringers, and around penetrations at ceiling and floor levels. Draftstopping (R302.12) was not read. | Inspect at vertical and horizontal concealed spaces in the factory before cover, with photo record. | Horizontal intervals not exceeding 10 ft in stud walls | blainemn.gov |
| Emergency escape and rescue openings ICC · IRC R310 (2020 Minnesota Residential Code text read) | Basements, habitable attics and every sleeping room need an emergency escape and rescue opening. Net clear opening area is at least 5.7 sq ft, with net clear height of at least 24 in. and width of at least 20 in.; grade-floor openings may be smaller per the code. Confirm the adopted edition and local amendments. | Window schedule and net clear opening are checked at the window install hold point against the approved plans. | 5.7 sq ft; 24 in. min height; 20 in. min width | stpaul.gov |
| Drywall levels of finish Gypsum Association / ASTM · GA-214 | Finish levels run 0 to 5. Level 4 is the level specified for smooth walls under flat paint. Level 5 (skim coat over the entire surface) is recommended for non-flat or gloss paint, dark tones and critical lighting. | Spec sets the level per room, and QA checks under raking light before paint. | nationalgypsum.com | |
| Paint and coating QA SSPC / ASTM · Manufacturer data sheets; ASTM D7091 (dry film thickness on metal) | ASTM D7091 is a practice for measuring dry film thickness of coatings on metal substrates with magnetic and eddy current gages, supplementing gage manufacturers' instructions. It does not apply to paint on drywall; interior paint thickness and cure follow the coating manufacturer's data sheet. | Interior paint is a QA spec item rather than a code item; use the data sheet's spread rate. | store.astm.org | |
| Tile installation standards TCNA / ANSI · ANSI A108 (installation) and A118 (materials); TCNA Handbook | A108 covers installation methods and A118 covers mortars, grouts and adhesives. Modules need deflection and movement considerations for transport. | Tile in wet areas is installed in factory over a suitable substrate, with movement joints and often a plan to regrout after set. | tcnatile.com unverified | |
| Flooring moisture testing ASTM · ASTM F2170 (in-situ relative humidity probes) | F2170 measures relative humidity in concrete slabs with in situ probes, to address excess slab moisture that can cause flooring failures. Flooring manufacturers often require such testing before installation, and they set the acceptance limits. | Precast floor planks or concrete topping would be moisture tested before moisture-sensitive finish flooring, per the flooring manufacturer. | store.astm.org | |
| Formaldehyde in composite wood US EPA · TSCA Title VI; 40 CFR Part 770 | Hardwood plywood 0.05 ppm, MDF 0.11 ppm, thin MDF 0.13 ppm, particleboard 0.09 ppm, measured by ASTM E1333-14. Products must be certified by an EPA-recognized third-party certifier and labeled. | Factory receiving checks the compliance label on cabinets, subfloor and trim stock and keeps supplier certificates. | Hardwood plywood 0.05, MDF 0.11, thin MDF 0.13, particleboard 0.09 ppm (40 CFR 770.10) | law.cornell.edu |
| EPA TSCA Title VI certification and labeling US EPA · TSCA Title VI | After March 22, 2019 composite wood products made or imported into the US must be certified and labeled as TSCA Title VI compliant by an accredited third-party certifier. EPA states TSCA Title VI and CARB ATCM Phase II limits are set at identical levels. | Incoming material inspection verifies labels; fabricators of finished goods have recordkeeping duties. | epa.gov | |
| VOC emissions testing for finishes CDPH / GREENGUARD / AIM · CDPH Standard Method v1.2; SCAQMD Rule 1113 (verify) | Voluntary or program-driven chamber emission testing of paints, adhesives and flooring, with regional VOC content limits for coatings. Not a model-code requirement for housing. | Specify low-VOC products; collect product data sheets and certificates for the QA file. | cdph.ca.gov unverified | |
| State approved quality assurance program State modular programs · South Carolina Modular Building Program regulations (S.C. Reg. 8-608; per Building Codes Council minutes) | In South Carolina, each modular manufacturer must have an approved quality control manual and appoint a quality control manager, and uses a third-party inspection agency. Council minutes state the regulations require annual in-plant audits of in-state manufacturers. Other states' rules differ and were not read. | The module's QA manual, quality manager and third-party inspection agency come from this layer. | Frequency: Annual in-plant audit (South Carolina regulations, per 2021 Building Codes Council minutes) | llr.sc.gov |
| Legal vehicle width US DOT / FHWA · 23 CFR 658.15 | States may not impose a width limit of more or less than 102 inches (about 8.5 ft). Special mobile equipment is exempt, Hawaii keeps 108 inches, and states may issue special-use permits for wider vehicles including manufactured housing. | Module widths above 102 inches ship on state oversize permits with route-specific conditions. | 102 inches | law.cornell.edu |
| Oversize load escort and route survey State DOTs · State oversize/overweight permit rules | The federal government does not issue oversize or overweight permits; this is a state option, so escort, pilot car and travel-time conditions come from each state a delivery crosses. | Route survey and per-state permits are arranged per delivery; do not publish numeric thresholds without a state source. | ops.fhwa.dot.gov | |
| Crane set checklist OSHA / ASME · OSHA 29 CFR 1926 Subpart CC (1926.1417, 1926.1404) | Under 1926.1417 the competent person must address the effect of wind, ice and snow on equipment stability and rated capacity, and on a storm warning decide whether to implement manufacturer recommendations for securing the equipment. No numeric wind limit is given. Rigging for crane assembly and disassembly must be done by a qualified rigger (1926.1404(r)). | Pick plan, rigging inspection and weather check are signed off before each module is lifted. | law.cornell.edu | |
| Module joint sealants ASTM · ASTM C920 | C920 classifies elastomeric joint sealants by type (S single-component or M multicomponent), grade (P pourable or NS nonsag), class (100/50, 50, 35, 25, 12.5) and use (T traffic or NT nontraffic, plus others). The manufacturer designates which apply to a given sealant. | Site crew seals module-to-module joints after set; rated joints need listed firestop. | store.astm.org |
30 items
Standards, inspection agencies and warranty
| Test or check | Requirement | Applied to a module | Criteria / frequency | Source |
|---|---|---|---|---|
| ICC/MBI 1200 off-site construction standard ICC / Modular Building Institute · ICC/MBI 1200-2021 | ICC's off-site brochure says Standard 1200 (Planning, Design, Fabrication, and Assembly) provides requirements for designers, manufacturers, transporters and assemblers so that off-site components are produced under a quality assurance/quality control process and can demonstrate building code compliance. The standards apply to componentized, panelized and modularized elements except manufactured housing. | Stratum's factory QA/QC plan and traveler system can be written to map to this standard so jurisdictions recognise it. | iccsafe.org | |
| ICC/MBI 1205 inspection and regulatory compliance ICC / Modular Building Institute · ICC/MBI 1205-2021 | ICC's brochure says Standard 1205 (Inspection and Regulatory Compliance) addresses compliance verification including permitting, in-plant and on-site final inspections, third-party inspections, and the roles of industrialized building departments, state modular programs and the AHJ. NEEP's brief adds that it enables third-party inspectors and remote virtual inspections for jurisdictions without statewide off-site programs. | Supports a model where an independent agency inspects in plant and the local AHJ inspects set and site work. | iccsafe.org | |
| 1200/1205 brief with adoption context NEEP · ICC/MBI 1200 and 1205 | NEEP's regional brief summarizes both standards, describes the model language on code officials and third-party inspectors, and says jurisdictions can adopt or integrate the standards into existing codes. It does not list which states have adopted them. | Use as a pointer on what the standards cover; confirm each state's adoption before claiming conformance. | neep.org | |
| Third-party agency independence and AHJ oversight NEEP summary of ICC/MBI 1205 · ICC/MBI 1205-2021 | NEEP's brief says third-party inspection agencies are independent (not involved in design, fabrication or construction) qualified companies providing impartial inspection, and remain subject to AHJ oversight. | Stratum should not self-certify; contract an independent state-approved agency. | neep.org | |
| IAS accreditation of third-party agencies (plan review) International Accreditation Service · IAS AC402; AC251 (as listed by ICC) | IAS AC402 (November 2015, effective January 1, 2016) is the IAS accreditation criteria for third-party permitting, plan review and inspection service providers. ICC's family-of-solutions brochure lists IAS accreditation under AC251 for plan review and permitting. | Choose agencies that hold current IAS accreditation and ask for the scope letter. | iasonline.org | |
| IAS criteria for inspection agencies (AC98, AC291) ICC / IAS · IAS AC98, AC291 (as listed by ICC) | ICC's family-of-solutions brochure lists IAS AC98 (Inspection Agency Accreditation) and AC291 (Special Inspection Agency Accreditation) under inspection. Which one a given state requires was not read. | Ask each candidate agency which IAS criteria it is accredited under. | iccsafe.org | |
| IAS AC472 / AC478 are metal-building programs International Accreditation Service · IAS AC472, AC478 | ICC's brochure lists AC472 as accreditation of fabricator inspection programs for metal building systems. IAS's AC478 brochure describes AC478 as a voluntary inspection program for assemblers of metal building systems. Neither is modular-specific. | Do not cite AC472 or AC478 as modular requirements. | iasonline.org | |
| ISO/IEC 17020 inspection body accreditation IAS / ISO · ISO/IEC 17020 | IAS states it accredits inspection agencies to ISO/IEC 17020, assessing competence to perform inspections, and IAS AC402 cites ISO/IEC 17020 as a general criterion. Which edition and which states require it were not read. | Prefer agencies with 17020 accreditation; it is an independence and competence signal. | iasonline.org | |
| ISO 9001 factory quality management system ISO · ISO 9001:2015 | Clause-level requirements were not read. Examples found are manufacturer claims of ISO 9001 certification, not independent evidence of what it demands of a modular plant. | Position ISO 9001 as an optional management-system layer, not a substitute for state agency inspection. | modules.ramirent.ee unverified | |
| CSA A277 factory certification CSA Group · CSA A277 | CSA's store page says A277 specifies the procedure for factory certification of manufactured, modular and panelized buildings, covering certification of the factory quality program, certification of the built product, auditing of the quality program, and in-factory inspection. The page lists the 2008 edition as withdrawn; a later edition was not read. A277 is a CSA standard, not an ANSI standard. | Possible future certification target; verify scope first. | csagroup.org | |
| CSA Z252 Canadian volumetric modular guide CSA Group · CSA Z252:23 | CSA's store page describes Z252:23 as a guide to compliance and approval processes for volumetric modular construction, covering plan review, permit packages, codes, factory certification procedures, third-party inspection roles, transport and storage, and on-site installation inspection. MBI partly funded its development. | Useful benchmark for factory certification content; Canadian, not US law. | csagroup.org | |
| NIBS Off-Site Construction Council guidance NIBS / AIA · Modular and Off-Site Construction Guide (2019) | NIBS lists the AIA-NIBS Modular and Off-Site Construction Guide (March 2019) as a primer on the modular approach for architects, covering value, pitfalls and case studies. The page does not describe plant quality control content. | Cite as industry guidance, not regulation. | nibs.org | |
| MBI quality or certification program Modular Building Institute · n/a | The MBI home page shows no factory quality certification program (it mentions only a members-only seals link), and no MBI program was found elsewhere. MBI co-developed ICC 1200 and 1205. | Do not claim MBI certification. | modular.org unverified | |
| Pennsylvania inspection frequency and storage/transport Pennsylvania (12 Pa. Code Ch. 145) · 12 Pa. Code 145.72a | Agency submits a recommended minimum inspection frequency, which the Department reviews and determines adequate. Agency inspects storage and transport methods and facilities at least monthly while the manufacturer retains title or control, and inspects units at the site after installation; onsite inspection documentation is kept at the factory and given to the Department within 30 days of request. Agencies may inspect more often based on professional judgment. | Plan for inspection of yard storage and transport securement, and keep records retrievable. | Storage and transport inspected monthly (minimum) Frequency: Monthly storage/transport; frequency otherwise proposed by agency and approved | law.cornell.edu |
| Pennsylvania inspection agency label Pennsylvania · 12 Pa. Code 145.61 | Agency attaches its insignia next to the data plate on each module, showing agency name and a serial number. | Each Stratum module carries state data plate plus agency label with serial traceability. | law.cornell.edu | |
| Texas in-plant inspection rules Texas TDLR · TDLR Industrialized Housing and Buildings in-plant inspection program (Rules Chapter 70) | Manufacturer designates in writing a TDLR approved and registered third-party inspection agency. Agency gives TDLR a written schedule of in-plant inspections at least seven days ahead. Minimum one inspection per module; system testing inspected at least every third inspection; energy design inspected every inspection (every third for buildings without envelope requirements). Increased frequency for new Texas manufacturers: 2 inspections per unit on the first 5 units, and 3 or more per unit on the first 10 units for manufacturers new to any state modular program. Forms IHB210 and 022ihb are required for every inspection; reports kept 5 years and filed with TDLR by the 10th of the following month. | Model Stratum's own hold-point schedule on at least this level for Texas units. | Minimum of one inspection per module; 2 per unit on the first 5 units and 3 or more per unit on the first 10 units for new-entrant manufacturers Frequency: System testing at least every third inspection; energy design every inspection | tdlr.texas.gov |
| Texas decal and data plate control Texas TDLR · Tex. Occ. Code 1202.204; TDLR in-plant inspection program | Inspector checks proper application of the data plate and decal or insignia; decals are confiscated at the exit interview and not returned until deviations are brought into conformance to the inspector's satisfaction. | Insignia issuance is a release gate before shipping. | tdlr.texas.gov | |
| Texas third-party inspector qualification for tall buildings Texas TDLR · 16 TAC Chapter 70 amendments | TDLR's adopted-rule summary requires ICC or NFPA fire inspector I certification for in-plant inspectors on projects over 75 feet and fire inspector II for installation inspectors on such projects. Not directly relevant to low-rise residential. | Likely not applicable to Stratum residential modules. | tdlr.texas.gov | |
| Virginia Compliance Assurance Agencies Virginia DHCD · 13VAC5-91 Industrialized Building Safety Regulations | 13VAC5-91: a compliance assurance agency (CAA) is an architect, engineer or organization approved by DHCD to investigate, test and evaluate industrialized buildings, provide factory follow-up at the point of manufacture, and provide a label. The State Building Codes Office (SBCO) keeps a list of approved CAAs, each manufacturer contracts with one or more CAAs, and the CAA notifies SBCO within 30 days of signing or ending a contract. Registered buildings carry a DHCD registration seal, a CAA label and a manufacturer's data plate. | Contract a Virginia-approved CAA; confirm audit and plan approval details with SBCO. | law.lis.virginia.gov | |
| California HCD DAA and QAA system California HCD · Health and Safety Code 19980; 25 CCR Ch.3 Subch.1 | HCD's insignia page says factory-built housing must bear an HCD insignia (Health and Safety Code 19980) placed before shipment. Insignia is issued only through an HCD-approved Quality Assurance Agency and only for units with prior plan approval under 25 CCR Ch.3 Subch.1. HCD's third-party agency page says agencies are certified as Design Approval Agencies and/or Quality Assurance Agencies. | Plans must be approved before insignia; QAA release before shipment. | hcd.ca.gov | |
| Indiana IBS third-party inspection Indiana DHS · 675 IAC 15-1.5 | Indiana DHS Code Enforcement Section administers the program under 675 IAC Article 15. In-plant inspections are done by DHS staff or an authorized third-party inspection company, and each unit must be inspected at one point during construction to be eligible for a serialized certification label. | One inspection per unit is the floor; Stratum hold points exceed it. | At least one inspection per unit during construction | in.gov |
| Washington L&I Factory Assembled Structures Washington L&I · FAS program | L&I says modular buildings built off site must be approved by L&I and carry an L&I insignia before shipping. Manufacturers submit plans for review by L&I, or may use an L&I-approved professional engineer or architect for plan review, with L&I still processing all plans; the L&I inspection process stays the same. Filing fees apply. | Budget for plan approval before first production unit; confirm inspection scheduling and notice rules with L&I. | lni.wa.gov | |
| Florida third-party agencies and insignia Florida DBPR · Fla. Stat. 553.37 (2025) | Current statute: the department approves manufacturers' drawings and quality control manuals, and approved inspection agencies must observe the first building from start to finish, then inspect each module at at least one point and at least 75 percent of subsystems of each module. The department adopts rules for approving third-party plan review and inspection agencies and monitors them. A building with department insignia and data plate is deemed to comply with the Florida Building Code and needs no additional local approval or insignia. | Keep insignia and data plate documentation for the local permit file. | flsenate.gov | |
| New York modular insignia of approval New York DOS · 19 NYCRR Part 1209 | DOS says modular buildings must meet the Uniform Code and State Energy Code and bear an Insignia of Approval under 19 NYCRR Part 1209, attached before shipment. Manufacturers must have a contractual agreement with a Department-approved Quality Assurance Agency (third-party inspection agency), which may perform in-plant inspections, Quality Assurance Manual review and approval, and insignia control. | Plan a NY plan submittal early; use a DOS-approved QAA. | dos.ny.gov | |
| UL modular building inspection UL Solutions · UL third-party inspection agency | UL Solutions' page says it offers plan review, factory and on-site inspections, installation site inspection and state insignias under state modular programs. UL filed a third-party inspection agency authorization renewal with Indiana DHS (the filing says none of its clients were yet producing under Indiana Article 15). Other states not confirmed. | Candidate agency; check state-by-state authorization. | ul.com | |
| ICC NTA off-site services ICC NTA · ICC 1200/1205 offerings | ICC NTA's page says it offers off-site solutions (plan review, engineering and inspection) aligned to ICC 1200 and 1205 and is accredited to the Code Council's standards for third-party off-site solutions. Promotional source. | Candidate agency; verify state approvals. | icc-nta.org | |
| 2-10 HBW modular structural warranty 2-10 Home Buyers Warranty · Builder warranty program | 2-10 HBW's page says the Modular Home Warranty provides 10 years of structural coverage from the sill plate up, upgradable to the full 2-10 warranty if the home is on a permanent foundation placed by a Builder/Dealer who is a program member; plus a 1-year workmanship warranty and 2-year distribution systems warranty. Itemized QA requirements not found. | Warranty is a market-facing assurance; QA records support underwriting. | 2-10.com | |
| Typical hold points before closing Industry practice · n/a | Texas requires inspection of each module at least at one point before completion of the structural, plumbing, mechanical or electrical phase, with system testing witnessed at least every third inspection and a procedural checklist (022ihb) at every inspection. Specific Stratum hold points (structure, MEP rough-in, insulation, air barrier before closing) are company practice, not stated in a source read. | Define Stratum hold points internally and publish them as company practice, not as a standard. | tdlr.texas.gov | |
| Documentation retention Texas TDLR / Pennsylvania · 16 TAC Ch.70; 12 Pa. Code 145.72a | Texas requires the manufacturer and the inspection agency to keep in-plant inspection reports for a minimum of 5 years; Pennsylvania requires post-installation inspection records on file at the factory and available to the Department within 30 days of request. | Retain travelers, NCRs and inspection reports for at least 5 years. | Frequency: 5 years (Texas) | tdlr.texas.gov |
| HUD vs modular distinction HUD / states · HUD Code vs state modular | NY DOS states modular buildings follow the Uniform Code and carry a state Insignia of Approval, and distinguishes them from HUD manufactured homes built to 24 CFR Part 3280. ICC's brochure says ICC 1200/1205 apply to off-site construction except manufactured housing. | State clearly that Stratum is modular under state programs, on a permanent foundation. | dos.ny.gov |
25 defects
Defects
| Area | Defect | Cause | Detection | Source |
|---|---|---|---|---|
| Steel fabrication | Undercut | Excess current/arc length or travel | Visual with gauge | ifactoryapp.com |
| Steel fabrication | Surface porosity | Contamination, shielding loss | Visual; MT/PT | ifactoryapp.com |
| Steel fabrication | Cracks at weld or toe | Hydrogen, restraint, residual stress, cold-formed corner | VT, MT, PT | jstage.jst.go.jp |
| Steel fabrication | Lack of fusion | Low heat input, poor technique | UT or RT | engstandards.lanl.gov |
| Steel fabrication | HSS corner cracking after galvanizing | Tight radius, strain-age embrittlement, restraint | Visual/MT at member ends after galvanizing | galvanizeit.org |
| Steel fabrication | Under-thickness HSS wall | A500 minus 10% tolerance | UT thickness gauge at receiving | steeltubeinstitute.org |
| Steel fabrication | Insufficient bolt pretension | Skipped snugging, wrong method | Matchmarks, DTI feeler gauge | dot.ca.gov |
| Steel fabrication | Galvanized bolt stripping or seizing | Insufficient lubrication, thread friction | Rotational capacity test | portlandbolt.com |
| Steel fabrication | Thin or missing galvanizing | Handling, drainage, surface | Magnetic gauge, visual | hotdipgalvanizing.com |
| Steel fabrication | Burst or blocked vent in galvanizing | Missing or small vent/drain holes | Design review before dip | galvanizeit.org |
| Steel fabrication | Coating damage at weld burn-off | Welding after coating or handling | Visual, DFT | hotdipgalvanizing.com |
| Steel fabrication | Out-of-tolerance camber/sweep | Mill or heat distortion | Straightedge and string line | aisc.org |
| Precast concrete and grout | Honeycombing | Poor consolidation, mix not meeting proportioning/mixing/molding requirements (INDOT manual) | Visual inspection after stripping; tap test; cores if structural | in.gov |
| Precast concrete and grout | Bug holes (entrapped air) | Entrapped air against form face | Visual inspection | in.gov |
| Precast concrete and grout | Form bleeding | Water/paste loss at form joints | Visual inspection after stripping | in.gov |
| Precast concrete and grout | Wall shadowing of reinforcement / insufficient cover | Insufficient concrete cover, possibly misplaced steel | Visual inspection; cover meter; pre-pour inspection of every piece per NPCA 4.3 | in.gov |
| Precast concrete and grout | Mispositioned reinforcement | Chairs/spacers displaced, poor tying | Pre-pour inspection documented per piece | precast.org |
| Precast concrete and grout | Fins or featheredge at joints | Form joint leakage | Visual; must be removed where it restricts jointing | in.gov |
| Precast concrete and grout | Edge cracking and spalling at joints | Handling, stripping, form removal damage | Visual; INDOT permits a single end crack not exceeding joint depth for pipe only | in.gov |
| Precast concrete and grout | Handling or stripping cracks | Lifting before adequate strength or improper lift points | Visual after stripping; strength records (cylinders or maturity) checked before lift | pci.org |
| Precast concrete and grout | Low concrete strength | Mix or batching error; improper cylinder making/curing | Cylinders per C39; cores per C42; NPCA audits check cylinder procedure | precast.org |
| Precast concrete and grout | Incomplete grout fill in splice sleeve | Blocked port, inadequate pumping, voids in joint | Grout must flow freely from upper port; WisDOT requires all sleeves completely filled | wisconsindot.gov |
| Precast concrete and grout | Cold-weather grout strength loss | Sleeve below 50 F at grouting or during cure | Temperature monitoring of covered sleeves; cubes tested at 24 h and 28 d | wisconsindot.gov |
| Precast concrete and grout | Weak shear key / closure bond | Smooth or dry substrate, laitance, contamination | Pre-grout surface inspection; bond test methods such as pull-off or slant shear (lab/mockup) | fhwa.dot.gov |
| Precast concrete and grout | Calibration drift in test equipment | Air meters and scales out of calibration | Plant audits check records; air meters every 90 days | precast.org |
Case record
Documented failures
| Project | What happened | Cause | Control that would have caught it | Source |
|---|---|---|---|---|
| B2 (461 Dean St), Pacific Park, Brooklyn NY (Forest City Ratner / Skanska modular tower) 2014-2015 | State documents obtained by FOIL and reported in 2015 (STV, owner's representative for Empire State Development) described water leakage through 2014: half of the first 39 apartments had significant water damage, the first four floors were described as largely gutted, modules were shipped unfinished with drywall left out near windows to allow leak repair, and some modules fit so tightly that drywall was shaved to fit them. Skanska and Forest City Ratner sued each other in September 2014; the documents do not establish who was at fault. | Not established. Each party alleged the other's failures (Skanska alleged design errors and omissions; Forest City alleged delays and lack of experience). Litigation outcomes on causation were not found. | Inference: a documented water/spray test of each module before shipment, and a dimensional check of module-to-module fit before dispatch, are the hold points that would have surfaced leak paths and tight fits in the factory. | brownstoner.com |
| 1 Branham Lane temporary housing, San Jose CA (Devcon / Volumetric Building Companies modules, LifeMoves) 2023-2024 | Modules arrived on site unfinished in October 2023 and mold developed after they sat in rain for weeks. A city housing memo dated 7 Nov 2024 cited deficiencies in factory-installed waterproofing, faulty exterior protective finish, missing firewall separations in mechanical rooms, and plumbing errors made at the factory. The site opening slipped from April 2024 to 2025. | Disputed. The city memo blamed the developer and its module subcontractor; the developer's president publicly attributed it to the module maker's workmanship; the module maker's CEO declined to comment on the memo. A separate report quotes the builder saying units were delivered dry but some were renovated on site after water infiltration. | Inference: factory third-party inspection of fire separations, plumbing pressure tests, and waterproofing before closing up, plus weather protection and moisture checks during staging. | sanjosespotlight.com |
| On Pak Court, Hong Kong (first subsidised HOS project using MiC) 2025 | TVB reported on 12 October 2025 at least 75 suspected water seepage cases after residents began moving in during July; repairs were completed in 58 cases. The Housing Department said the situation may be related to module quality. | Not confirmed. The Housing Department said the cause may relate to module quality; no final finding was found. | Inference: unit-level water ponding/spray test records at factory and again after installation and joint sealing, as ADV-36 asks AP to review. | news.tvb.com |
| Light public housing MiC sites at Siu Lam, Tuen Mun and Chai Wan, Hong Kong 2025 | Hong Kong authorities reported 23 screws cut without permission at Siu Lam (found in a regular ASD inspection on 30 August); later checks across three sites run by the same joint venture found about 6 percent of 4,000 screws cut short or severed, and about 2,000 connecting holes on iron plates enlarged without authorisation. The contractor was ordered to remove and reinstall the affected modules at its own cost, per press coverage. | Housing Bureau account: unauthorised modifications by a subcontractor's worker, since dismissed. Experts quoted in press suggested material defects and weak supervision as other possible factors; no final cause report was found. | Inference: a witnessed hold point with torque and length verification of module-to-structure connections before cover-up, with photo records. | thestandard.com.hk |
| Bathroom pods in NSW apartment buildings (audits cited by Building Commission NSW) 2024 (paper date) | The Building Commission NSW position paper states that audits of NSW apartment buildings built with bathroom pods found non-compliant plumbing fixtures, non-compliant waterproofing and unsafe electrical wiring, remediated at cost to developer and builder. | Per the paper: substandard design and building work, and insufficient thought by on-site designers and builders about integrating offsite components. | Inference: independent verification of waterproofing and electrical compliance at pod fabrication, and a documented interface check at installation. | architecture.com.au |
| Steel-framed modular hotel, Florida (unnamed; forensic engineer case study) not stated | A forensic engineering firm reports floor-pan corrosion beneath guest rooms and mold on demising walls at box-to-box joints. The make-up air system could not pressurise the building because spaces between boxes were too leaky; damaged walls were rebuilt with conventional structure. | Per the firm: humid air moving through leaky inter-box cavities and condensing on metal pans. Firm article, not peer reviewed; project unnamed. | Inference: air-leakage testing of the assembled envelope and inter-module cavities, and coordinated HVAC pressurisation commissioning. | buildingforensicsgroup.com |
| Assisted living facility, Florida (unnamed; same forensic firm article) not stated | Condensation formed on the belly wrap and wood framing in a marriage-wall cavity and a third-floor pan underside, with surface temperatures as low as 68 F in areas in direct airflow from room PTAC units. | Per the firm: crawl space hard to isolate from cavities, cavities open or poorly sealed; crawl space often designed by base-building designer rather than module maker. | Inference: continuous air barrier inspection at marriage walls and a moisture check of concealed cavities before close-in. | buildingforensicsgroup.com |
| Moxy Hotel, Stobcross Street, Glasgow (Robertson) 2019 | On about 17 September 2019 a chain separated from a lifting beam while a prefabricated module was being lifted to the 10th floor by a luffing crane. The module hung from the remaining chain, was steadied and landed with no injuries; Robertson suspended similar lifts pending investigation. | Not stated; under investigation per Construction Enquirer. | Inference: documented lifting-gear inspection and a lift plan hold point before each module lift. | constructionenquirer.com |
| Madison Street, Oak Bluffs MA (modular home set) 2017 | A crane toppled onto a modular home during installation on 19 July 2017; no injuries reported. The article says the operator shifted the machine's balance, causing the tip-over. | Per Martha's Vineyard Times: operator shifted the crane's balance. | Inference: crane set-up and ground-bearing check with a lift plan sign-off before the set. | mvtimes.com |
| 25th and Corby, North Omaha NE (modular townhomes) 2026 (date not on page) | During a crane lift one modular townhome section fell onto another. No injuries per the developer; the cause was under investigation and the timeline uncertain. | Not established. | Inference: rigging inspection and lift-plan verification hold point. | 3newsnow.com |
Surveys and reports
| Report | Finding | Source |
|---|---|---|
| Defect Occurrence and Management in Prefabricated Commercial Construction in Australia Parrotte, Li, Tivendale (Deakin University) 2020 | As cited by Building Commission NSW and a search summary: defects in prefabricated components are often more expensive to fix than in typical construction, and defect management systems specific to prefabricated construction were found absent, especially in the commercial sector. No numbers read. | dro.deakin.edu.au |
| Modern methods of construction: views from the industry (NF 70) NHBC Foundation / Lychgate Projects not stated | Per NHBC page summary: more than 160 senior respondents in England and Scotland; 98 percent had used or considered an MMC approach in the prior three years; over 75 percent of house builders cited faster programmes and over 50 percent linked MMC to better build quality. These are perceptions, not measured defect rates. | nhbc.co.uk |
| LCQ5: Modular Integrated Construction method (government reply) Hong Kong Development Bureau 2024-2025 | Records from management parties: approximately one per cent of units in completed MiC projects (2020-2024) had water leakage or seepage; the reply says this is lower than traditional methods and most cases were resolved. Government-reported figure. | devb.gov.hk |
| Causes of defects associated with tolerances in construction: A case study Talebi, Koskela, Tzortzopoulos, Kagioglou, Rausch et al., Journal of Management in Engineering not stated (DOI 10.1061/(ASCE)ME.1943-5479.0000914) | Two case-study projects (general construction, not modular-specific): eighteen potential causes derived for eleven observed tolerance issues; abstract calls tolerance defects among the most costly and recurring. | open-access.bcu.ac.uk |
| Benchmarking and improving dimensional quality on modular construction projects: a case study Rausch, Edwards, Haas (University of Waterloo), International Journal of Industrialized Construction 2020 | Two near-identical modular projects compared using as-built vs nominal 3D scan data; improvements introduced in the second reduced rework. Abstract states stricter dimensional demands of modular are not fully addressed in guidelines. No numbers read. | doi.org |
Regulated programs
Mandated programs
| Program | Jurisdiction | Requirements | Source |
|---|---|---|---|
| Singapore BCA PPVC Information Kit (Version 2, 2026) | Singapore | As read: Section 4.3 lists quality assessments: Precaster Accreditation Scheme (PAS) / Structural Steel Fabricators' Accreditation Scheme for shell production, Manufacturer Accreditation Scheme (MAS) for fit-out production, CONQUAS for workmanship, and BCA Quality Mark for internal finishes and water tightness of completed dwelling units. Section 3.3 states design/detailing good practices: for cast-in MEP, compliance tests offsite before delivery and overall MEP testing and commissioning once more after on-site connections; waterproofing upturn of at least 300 mm and 150 mm application beyond wet area; 1,800 mm waterproofing height at shower walls; at least three barriers at structural joints; remove trapped water between modules before grouting/stitching. Section 4.6: NDT at selected points on modules with visible casting defects. The kit labels these as good practice. I did not find a water test duration in the documents I could read. | isomer-user-content.by.gov.sg |
| Singapore PUB Code of Practice on Sewerage and Sanitary Works, 3rd Ed (Mar 2025), clause 4.5 | Singapore | As read: PUB approval is needed for prefabricated bathroom units or PPVC. A high-pressure air test shall be conducted for every PBU or PPVC module at the factory; if WCs and floor traps are pre-installed, a low-pressure air test with WCs and floor traps charged with water shall also be done for every module at the factory. A 5 mm steel plate embedded below any shallow floor trap. | pub.gov.sg |
| Hong Kong Buildings Department PNAP ADV-36 (Rev. 7/2025), MiC quality control and supervision | Hong Kong | As read: modular units to be fabricated by a factory with a valid Full Certificate under the MiC Manufacturer Accreditation Scheme (BTRi), ISO 9001 or equivalent, imposed as a plan-approval condition; certificate or Quality Assurance Scheme submitted at least 14 days before production starts. Authorized Person, Registered Structural Engineer and Registered Contractor staff to visit the factory in person for the first batch, then audit at least monthly (in person quarterly, videotelephony allowed in between), with endorsed reports to BD within 14 days. AP checks include drainage, window water tightness, and for finishes 'reports of water ponding tests/spray tests'; open-up audit check of fire-resisting dry walls. RSE checks include opening up concrete at three locations (100 x 300 mm) for rebar, covermeter at six locations, rebound hammer at three locations, NDT of welds, tensile test of one specimen per 40 tonnes of steel. ADV-36 also notes modular construction has more joints and gaps prone to seepage. No water test duration is stated in the text I read. | bd.gov.hk |
| Hong Kong DEVB MiC Manufacturer Accreditation Scheme (MiC-MAS) and LegCo reply LCQ5 | Hong Kong | As read in the government reply: DEVB commissioned the Building Technology Research Institute to run MiC-MAS (applications from November 2024), certifying manufacturers on management, production and transportation. Each module is tested for structure, finishes, and electrical and mechanical installations before leaving the factory, including water leakage and seepage tests, and carries an identification code. DEVB Technical Circular 2/2026 reportedly supersedes TC(W) 4/2024 (per search summary; not opened). | devb.gov.hk |
| Building Commission NSW position paper on regulation of prefabricated buildings (Draft Building Bill 2024) | New South Wales, Australia | Proposal only, not final government position (paper says so). Notes that NCC does not cover manufacturing-process factors such as transport loads, and that once a prefabricated home is installed there is no current regime to ensure it is compliant and free from defects; proposes treating manufactured buildings as building work with a certification role. | architecture.com.au |
| ABCB National Voluntary Certification Scheme for Manufacturers of Modern Methods of Construction | Australia | Consultation closed 29 August 2025; Commonwealth wants the scheme to start in mid-July 2028, per search summaries. I did not read the issues paper, so no test or hold-point content is claimed. | consultation.abcb.gov.au |
US state modular inspection models
| State | Agency | Inspection model | Source |
|---|---|---|---|
| Pennsylvania | Dept. of Community and Economic Development (DCED), Housing and Buildings Standards; Industrialized Housing Act, 12 Pa. Code Ch. 145 | Department-approved third-party inspection agencies; agency-proposed frequency reviewed by the Department; monthly storage/transport checks; post-installation site inspections | law.cornell.edu |
| Texas | TDLR Industrialized Housing and Buildings | TDLR-registered third-party inspection agencies; minimum one inspection per module; forms IHB210 and 022ihb; decal/insignia control | tdlr.texas.gov |
| Virginia | DHCD State Building Codes Office | Private compliance assurance agencies evaluate buildings and provide factory follow-up and labels; manufacturers contract with an SBCO-listed agency; DHCD registration seal | law.lis.virginia.gov |
| Indiana | Dept. of Homeland Security, Code Enforcement Section | DHS staff or authorized third-party inspectors; each unit inspected at one point during construction; certification label per unit | in.gov |
| California | HCD Division of Codes and Standards, Factory-Built Housing | HCD-certified Design Approval Agencies and Quality Assurance Agencies; HCD insignia issued only through an approved QAA for plan-approved units | hcd.ca.gov |
| New York | Dept. of State, Division of Building Standards and Codes | DOS plan approval and Insignia of Approval; contract with a Department-approved Quality Assurance Agency (third-party inspection agency) | dos.ny.gov |
| Florida | DBPR, Building Codes and Standards (Manufactured Buildings) | Department-approved third-party plan review and inspection agencies; inspection of each module at least once and 75 percent of subsystems; department insignia and data plate | flsenate.gov |
| Washington | Dept. of Labor and Industries, Factory Assembled Structures | L&I plan review (or L&I-approved engineer or architect review); L&I inspection process; L&I insignia required before shipping | lni.wa.gov |
Not verified
Unverified
- No Stratum production test data. Items marked unverified rest on secondary sources.
- AISC site pages (program requirements, SSC FAQs, Steelwise PDFs, 341-22 text) returned 403; AISC 303 numeric tolerances and 360 text not read.
- No primary D1.1 text read: visual table limits, NDT sampling rates, prequalified WPS conditions, clause numbers. Item 11 (visual criteria) kept unverified with numeric limits removed.
- RCSC Specification not read directly; pretensioning items rely on Caltrans BCM 55-1.03 and university course notes. Five-method list with combined method, DTI feeler gage thickness and F436 washer rule not confirmed.
- No source for module squareness or diagonal tolerance (item dropped).
- CWI role, visual-before-NDT item and member tolerances kept as unverified qualitative items.
- A6 and A500 MTR chemistry/tensile limits not retrieved; SSPC-SP surface prep, D4541 pass criteria for duplex coatings, AWS D1.3 and first-article practice not researched.
- Defects table: porosity/lack of fusion/camber causes are general knowledge; the AISC camber page was not readable.
- ASTM full standard texts are paywalled; ASTM items rest on store scope pages, INDOT/NPCA/WisDOT/TxDOT documents, or other agencies' specs. Numeric limits inside ASTM test methods (C1064, C231, C138) are not sourced.
- AC133, ACI 318, ACI 301 and ACI 117 clause text not read. Only the 9 in. slab ACI 117 values from an ACI webinar slide are supported; the 1/4 in. band for members 4 in. or less is unconfirmed.
- PCI MNL-116 text not read. PCI 135 / MNL-135 tolerance values and final status not retrieved (PCI draft pages returned 404); hollow-core camber tolerances not found.
- No sourced stripping-strength threshold for slabs; only the 3,000 psi lifting-loop minimum from the PCI Bridge Design Manual.
- Minimum number of cores and core acceptance limits not read from a primary source (ACI 318 paywalled).
- ACI 228.2R, ASR screening methods (C1260/C1567), MNL-124 hourly rating values, MNL-128, MNL-137, and proprietary lifting insert safety factors not sourced.
- Grouted sleeve spec numbers are from WisDOT (bridge piers) and TxDOT 2004 (bridge deck grout); they are examples, not module requirements. ESR-4275 covers threaded splices, not grouted sleeves.
- INDOT manual criteria are pipe-focused and do not transfer to module slabs.
- No physical module-scale gravity, racking or shake table test with ATC-24 or AISC 341 Chapter K protocol was read in full.
- ASCE 7 R, Cd, Omega values and tie-force provisions not read from the standard (ASCE page only describes scope); IBC Table 1604.3 values, UFC 4-023-03, ASTM E564, ICC/MBI 1205 scope and AISC 341 Chapter K not read.
- Walking vibration acceptance limits (Design Guide 11, SCI P354) not retrieved; SCI item dropped.
- Numeric transport acceleration values (Godbole 2020 Eng. Struct.) not retrieved; no standard DAF for module lifting confirmed (ISARC paper cites DnV 1.5 secondhand).
- BTH-1 design factors and B30.20 proof load values, ACI 318 Ch. 17 text not verified.
- No source found for foundation set tolerances, as-built survey acceptance, fire design, or structural health monitoring of modular housing (items dropped).
- Auckland slider shake table study and DesignSafe MTB2 page only partly readable; Engineering Structures transport damage item (DOAJ) returned 403 and stays unverified.
- ICC code site (codes.iccsafe.org) and up.codes were not readable; IECC 2021 text was read via Yakima County's reproduction of IECC Chapter 4. 2024 IECC edition numbers (R402.4.1.2, R402.4.1.3) were not confirmed.
- IBC dwelling-unit sound separation was read in the 2025 California Building Code text (a state adoption of the IBC), not the ICC IBC itself; IBC section numbering (1206 vs 1207) and the field metric names (NNIC, NISR vs ASTC, AIIC) by edition were not confirmed from the ICC text.
- Passive House new-build n50 value (0.6 per hour) not read; the PHI page read gives only the EnerPHit Unit qE50 of 1.0 m3/(h m2) and says an airtightness test is part of final review.
- ASTM pages were read at scope level only; test pressures, durations and spray rates for E331 and E1105 Procedure A/B pressures are not stated in the sources read, so no numeric criteria are kept. E1105 procedure durations came from a Construction Specifier article.
- NFRC 100 was read through an Intertek summary and NFRC 200 through a separate Intertek summary (w3inte.intertek.ch/building/standards/ansi-nfrc-200/); nfrc.org pages were not readable. FGIA/AAMA standard texts (501.2, 502, 503, 1503-09, 2603-2605, NAFS) are paywalled; AAMA 1503 was read in the 1988 edition on law.resource.org.
- ISO 6781:1983 is withdrawn (2023) and replaced by ISO 6781-1:2023, whose scope was not read.
- NFPA 285 scope text itself was not read; the San Diego bulletin describes the California trigger only, and IBC triggers were not confirmed.
- ASHRAE 90.1 Appendix A tables were not read; only addendum aw text describing Table A9.2-2. ASHRAE 160 and Guideline 0/1.1 were read through publisher and trade descriptions.
- BC Hydro guide steel stud effective R-value tables not extracted; only methodology and the 20-70 percent statement read.
- No published standard found for inter-module joint testing.
- ASTM G101, zinc cladding, terracotta (ASTM C67), E2307 and E1996 criteria not researched.
- Building America Solution Center was read only through a third-party description of the DOE resource; DOE pages were not readable.
- Water supply test (IRC P2503.7): only a secondary study guide was readable; 'working pressure, 15 minutes, 50 psi air' is unconfirmed against code text and the 1.5x figure is unsupported, so it is not claimed.
- No NEC text or NFPA 70, 70B, 70E scope text was readable (NFPA pages carry titles only); those items stay verified:false. GFCI and AFCI locations come from an EC&M trade article, not code text; UL 943 and UL 1699 listing was not confirmed.
- Smoke and CO alarm items rest on ICC code-change proposal documents, not adopted IRC text, so they are verified:false.
- Duct leakage limits are from Washington State amended 2021 IRC/IECC text and blower door limits from the 2012 IRC as adopted by Pima County; other editions and states differ.
- ENERGY STAR Grade I requirement is from Rev. 14 National Rater Field Checklist; footnote alternatives apply. Moisture-meter checks on lumber are not in the ENERGY STAR documents read and were dropped.
- Draftstopping (R302.12), ASTM F1869, ASTM C840, ASTM C1193, ANSI A108/A118, CDPH Standard Method v1.2 and ACCA manuals were not read.
- Egress sizes are from the 2020 Minnesota Residential Code (based on the IRC); grade-floor exceptions and sill height were not captured.
- State QA program: only South Carolina was read, and the annual audit statement comes from Council minutes rather than regulation text. Other states' requirements are unverified.
- Crane set: signal person rules and numeric wind limits were not read; Subpart CC gives no numeric wind limit in 1926.1417.
- No sourced modular KPI numbers (defects per module, rework hours, first-pass yield) were found; none are included.
- ICC 1200/1205 clause text not read (paywalled); requirements come from ICC's brochure and NEEP's brief.
- State adoption of ICC 1200/1205 not verified (item dropped); ICC committee page lists second-edition public review underway.
- IAS criteria required by individual states for modular inspection agencies not confirmed; ISO/IEC 17020 edition not read.
- ISO 9001 clause requirements not read (ISO and ASQ pages blocked); only a manufacturer claim cited, so that item stays unverified.
- CSA A277: only the withdrawn 2008 edition page was read; current edition scope unconfirmed. MBI factory certification program not found.
- 2-10 HBW itemized QA requirements, RWC and other warranty programs not verified.
- Builders risk and transit insurance QA requirements not researched.
- Delivery acceptance criteria and typical NCR/traveler formats lack primary sources.
- Virginia state audit and plan approval procedures not confirmed beyond the 13VAC5-91 text read; Washington notice periods (7-day inspection requests) and WUI checklist not found on the L&I pages read.
- Texas page read is the TDLR in-plant program document (revised January 2010); confirm against current 16 TAC Chapter 70. New York rules read only via the DOS program page, not 19 NYCRR text.
- Singapore PPVC bathroom water test duration (for example 24 hours ponding) was not found in an official document I could read; a third-party blog claims 24 hours for CONQUAS wet areas, unverified. The CONQUAS manual notes factory test samples are capped for PPVC (20 percent wet area, 30 percent windows per search summary), not opened.
- Hong Kong ADV-36 requires ponding or spray test reports but the text read gives no duration; HK MiC-MAS technical criteria were not obtained.
- No NIST, Modular Building Institute or Dodge report with numeric defect rates was found. A 44.1 percent on-site assembly workmanship root-cause figure appeared in a ResearchGate snippet with unclear source and is deliberately not used.
- Katerra, Ilke Homes and Legal & General Modular failures were reported as financial, not defect, cases.
- No numeric defect-rate report from NIST, MBI or Dodge was found.
187 sources
Sources
- aisc.org https://aisc.org/steel-solutions-center/engineering-faqs/3.2.-member-straightness-toleranc…
- app.aws.org https://app.aws.org/forum/topic_show.pl?pid=11528
- app.aws.org https://app.aws.org/mwf/attachments/78/163778/AuditPoliciesrevision1-09.pdf
- blog.projectmaterials.com https://blog.projectmaterials.com/epc-projects/testing-inspection/mill-test-certificates-3…
- buildingscience.com https://buildingscience.com/documents/digests/bsd-013-rain-control-in-buildings
- buildingscience.com https://buildingscience.com/documents/reports/rr-0907-ventilated-wall-claddings-review-per…
- codehub.building.govt.nz https://codehub.building.govt.nz/home/resources/ansiaisc-341-05
- consultation.abcb.gov.au https://consultation.abcb.gov.au/national-voluntary-certification-scheme-for-manufacturers…
- designsafe-ci.org https://designsafe-ci.org/community/news/2022/april/testbed-shakedown-nheri-uc-san-diego-s…
- doaj.org https://doaj.org/article/c9b61f1948a741ac919308d4323c7032
- doi.org https://doi.org/10.29173/ijic212
- dos.ny.gov https://dos.ny.gov/code/factory-manufactured-buildings-modular
- dot.ca.gov https://dot.ca.gov/-/media/dot-media/programs/engineering/documents/structureconstruction/…
- dro.deakin.edu.au https://dro.deakin.edu.au/view/DU:30145573
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- engstandards.lanl.gov https://engstandards.lanl.gov/esm/welding/vol1/GWS 1-05-Att.04-R1.pdf
- eziil.com https://eziil.com/?p=9171
- fgiaonline.org https://fgiaonline.org/about/news-and-blogs/fgia-updates-suite-of-finishes-documents-for-a…
- fgiaonline.org https://fgiaonline.org/product-certification/insulating-glass/igcc-igma-certification-prog…
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- floridabuilding.org https://floridabuilding.org/FBC/thecode/Code_Dev_2007_supplement/TABLE_1604.3.pdf
- ftp.mdt.mt.gov https://ftp.mdt.mt.gov/other/webdata/external/materials/materials_manual/407.pdf
- galvanizeit.org https://galvanizeit.org/knowledgebase/article/astm-a123-a123m
- galvanizeit.org https://galvanizeit.org/knowledgebase/article/corner-cracking-of-round-and-rectangular-hss
- galvanizeit.org https://galvanizeit.org/knowledgebase/article/required-vent-drain-holes-for-hollow-structu…
- galvanizeit.org https://galvanizeit.org/knowledgebase/article/venting-and-drainage-holes-in-square-and-cir…
- gocodebook.com https://gocodebook.com/library/us/ca/ca-building-code/chapter-12-interior-environment/sect…
- icc-es.org https://icc-es.org/wp-content/uploads/report-directory/ESR-4275.pdf
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