Soil decides the budget
Expansive clay, high water tables, and rock all force design changes: thicker slabs, piers, or engineered fill. A $1,500 geotechnical report before design is the cheapest insurance in the whole project.
- • Frost depth sets minimum footing depth — deeper in northern climates.
- • Add perimeter drain and a sump if the water table is within 3 ft.
- • Vapor barriers under slabs are cheap now, impossible to retrofit later.
FAQ
How much does a house foundation cost?
Slab foundations for a 1,600 sq ft home typically run $15,000–30,000 all-in; a full basement on the same footprint runs $80,000–120,000.
Which foundation type is best?
Slabs win on cost in warm, flat, well-drained sites. Crawl spaces make sense where you need access to plumbing or the lot slopes. Basements pay off in cold climates where you're digging below frost depth anyway.
How long does a foundation take to cure?
Concrete reaches enough strength for framing in about 7 days and full design strength around 28 days. Rushing framing on green concrete risks cracking at anchor points.
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