How do I evaluate a modular or prefab building manufacturer's website before sending plans or a spec?
Check the building class and structural certification the manufacturer holds, the fire performance classification for the application, and the module dimensions and tolerances that govern what can be delivered to the site. Then check installation support and site craneage requirements, because prefab construction is a logistics operation where the handover is where most failures happen.
A project manager is selecting a modular supplier for a building programme where the site programme depends on delivery and installation dates being met.
Reviewed 4 August 2026
Scope and specifications
- Building type and application
- Classrooms, healthcare, residential and commercial fit-out are different products.
- Structural certification and building class
- The regulatory classification the building authority will reference.
- Fire performance classification
- Required for the building type and occupancy.
- Module dimensions and weight
- Determines transport, craneage and site access requirements.
- Dimensional tolerance specification
- Governs how modules join and whether the structure is accurate on site.
- Acoustic and thermal performance
- Often regulated for the building's intended use.
- Foundation and site preparation requirements
- Prefab still needs a prepared foundation, and it is the interface where failures occur.
Documents buyers may need
| Document | What it proves | Where it belongs |
|---|---|---|
| Structural certification and building class documentationAsked at: building approval — mandatory | Conformity with the structural standard for the building class claimed | Publish it |
| Fire performance classification reportAsked at: regulatory approval | Reaction to fire for the materials and assemblies used | Publish it |
| Technical datasheet for the module systemAsked at: specification | Dimensions, tolerance, thermal, acoustic and structural values | Publish it |
| Acoustic and thermal performance dataAsked at: building compliance calculation | Performance values with the test methods named | Publish it |
| Foundation and site preparation specificationAsked at: before order — determines site feasibility | What the manufacturer needs prepared before delivery | Publish it |
| Installation method statementAsked at: programme planning | Crew, craneage, sequence and duration for installation | Publish it |
| Warranty termsAsked at: before contract | Coverage for structure, weathertightness and defects, with periods | Publish it |
Details for a useful enquiry
- Building type, application and occupancy
- Determines the regulatory requirements.
- Number of modules and overall area
- The basis of the quote and the logistics plan.
- Site location, access and craneage
- Delivery and installation feasibility.
- Foundation condition
- Determines preparation needed before installation.
- Programme dates for delivery and handover
- Modular construction is a fixed-sequence operation.
- Fire, acoustic and thermal requirements
- Set by the building regulation for the use.
Questions suppliers ask
Why does the structural certificate matter more than the product brochure?
Because the building authority will approve on the basis of the certificate, not the brochure. A manufacturer who publishes the certificate and the building class is shortlisted; one who claims it without evidence cannot be specified, because nothing in the submission can be substantiated.
How should installation requirements be presented?
With the craneage needed, the crew size, the sequence, the duration, and what the site must have prepared in advance. Modular installation is a logistics operation, and a manufacturer who explains it clearly is protecting both their own delivery and the buyer's programme.
What should a foundation specification include?
The bearing capacity required, the tolerance the foundation must achieve, and the interface detail between the foundation and the module. Failures at this interface are common, and a manufacturer who publishes the requirement can demonstrate that a subsequent failure came from the foundation rather than the building.
Check which documents and standards your buyer needs; requirements vary by market, customer and contract.
Plact Research. Plact's editorial desk for buyer-evidence research. Industry standards, documents and buyer questions are researched and drafted with Plact's AI tools, then reviewed by Praveen Kavuri before publication. Every claim cites the standard, regulation or public source it rests on.
Related buyer questions
Put this to work on your website
See how Plact helps buyers find what you offer and send a useful enquiry.