Modular Homes ExplainedFactory-built permanent homes, planned for their destination
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Factory Inspections and Site Inspections

Modular quality assurance uses coordinated inspections in the plant and at the destination because some work becomes concealed before shipment.

Reviewed for destination-code contextInternational with U.S. and Canadian emphasis
Permanent-home context: This guide uses “modular home” for a code-compliant building made as three-dimensional modules, transported to a permanent site and assembled on an approved foundation. It does not use the term as a synonym for a trailer, mobile home or HUD-code manufactured home.

Factory inspection

Approved agencies may inspect structural, plumbing, electrical, mechanical and energy work during production. The factory quality program controls materials, procedures, records and corrections.

Inspection does not mean every item is observed continuously. The approved quality system and sampling or inspection schedule should be understood.

Site inspection

Local officials review foundations, placement, structural connections, service hookups and work completed after delivery. They may also verify module labels and approved plans.

Site crews should avoid covering connections or penetrations before required inspections. Coordinate inspection access with weatherproofing needs.

Handling nonconformance

Damage in transit, field modifications and missing labels need a documented resolution. The factory, approval agency, designer and local authority may all have roles.

Keep photographs and inspection reports, and identify who has authority to approve a repair rather than relying on an undocumented field fix.

Apply this guide to a real project

For factory inspections and site inspections, create a dated project note tied to the destination address and current drawing revision. Identify the authority, designer, factory or contractor responsible for each unresolved item. Attach the written evidence for ‘What factory inspections are required and who performs them?’ and ‘Which work must remain visible for local inspection?’ rather than recording a verbal assurance.

Before a deposit, production release, shipment or final payment, convert every open question into a named action with an owner and deadline. Keep superseded drawings and decisions in the record so later inspectors, lenders, insurers and future owners can understand why the completed house differs from an early sales plan.

Questions to resolve before proceeding

  • What factory inspections are required and who performs them?
  • Which work must remain visible for local inspection?
  • How are transport damage and field changes reviewed?
  • Who issues the final occupancy approval?
Stop point: Do not conceal module connections or repairs until the responsible inspector has released them.

Primary references to check