What this due-diligence check covers
Web Soil Survey provides mapped soil units and interpretations. A geotechnical investigation can evaluate subsurface layers, bearing, shrink-swell, groundwater and fill where project risk justifies it.
Septic suitability and structural foundation suitability are related to soil but are not the same test.
Why it matters before closing
Problem soils can increase excavation, drainage, stabilization and foundation cost or change the building location.
What to verify
- Review official soil mapping and interpretations.
- Walk for cracking, fill, seepage and erosion indicators.
- Ask the designer what investigation is appropriate.
- Price likely foundation and earthwork contingencies.
Red flags that deserve follow-up
- Uncontrolled fill or former pond area.
- High shrink-swell rating.
- Shallow bedrock where basements are planned.
- Wet or organic soils in the building area.
Evidence to keep in the parcel file
- Soil survey report
- Geotechnical scope or report
- Topographic and drainage information
- Foundation assumptions and allowance
Questions to ask before the deadline
- What soil units cross the building area?
- Is fill present?
- What foundation system is likely?
- Will groundwater or rock affect excavation?
- What contingency should the budget carry?