Prepare the questions and evidence needed for a qualified professional to design the project foundation.
A modular-home foundation is a site structure that must carry project-specific loads, manage soil and water, connect utilities, support module setting, and satisfy the adopted local code. Generic diagrams are orientation tools, not construction documents.
Start with evidence below and around the home
Provide the designer with survey information, soils evidence, grading and drainage concept, frost and climate criteria, flood or hazard information, utility entries, module loads, connection details, and set method. A foundation choice made before these inputs may simply move cost and risk into later revisions.
Define the performance questions
- What vertical, lateral, uplift, and connection loads must be transferred?
- How will water drain away and below-grade assemblies stay dry?
- Where will utilities enter and remain accessible?
- What clearances are needed for transport, crane, set, and module connections?
- How will insulation, air sealing, pests, radon, and ventilation be addressed?
- Which inspections occur before concrete, backfill, set, and concealment?
Compare options as complete assemblies
| Concept | Potential use | Questions that control fit |
|---|---|---|
| Slab or shallow system | Sites and designs suited to limited below-grade space | Frost design, utilities, anchorage, level tolerance |
| Crawl space | Service access and raised construction | Moisture, insulation, drainage, clearance, access |
| Basement | Below-grade space and deeper support | Excavation, groundwater, waterproofing, egress, cost |
Move from concept to accepted foundation
- Collect site and module design inputs.
- Confirm applicable code and review authority.
- Compare complete scopes, not concrete quantities alone.
- Coordinate openings, embeds, plates, anchors, and tolerances.
- Inspect before irreversible work is covered.
- Survey and document readiness before scheduling the set.
Avoid foundation scope gaps
- Manufacturer and site designer using different load or dimension revisions
- Unpriced excavation, dewatering, rock, unsuitable soil, or backfill
- Utility sleeves and access added after concrete
- Set crew arriving without accepted elevations and bearing locations
Create a foundation acceptance package
Keep approved drawings, calculations when required, geotechnical or soil information, concrete and reinforcement records, survey or elevation evidence, waterproofing and drainage documentation, required inspection approvals, photographs before concealment, and the module-set readiness sign-off in one project record.
Continue with the next decision
Sources and further reading
Primary and contextual sources used to verify definitions or give readers a relevant next resource.
- HUD minimum property standards Official portal to federal minimum-property and permanent-foundation reference material; modular projects still require the locally applicable design path.