Definition
A slab is a concrete foundation where your home sits directly on the ground—no basement, no crawl space. It's economical but vulnerable to heaving from soil expansion when moisture conditions shift.
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Slab foundations are economical but can suffer from heaving (upward movement from soil expansion) or settling (downward movement). They require careful grading to direct water away from the structure and proper soil preparation before pouring. Slab-on-grade construction makes plumbing repairs costly since pipes run through the concrete. Slab homes require regular perimeter drainage maintenance.
Pro Tip
Keep moisture levels consistent around slab foundations. Good grading and perimeter moisture management prevent expensive heaving problems.
Example
A buyer in Texas purchased a home on a slab foundation in an area with expansive clay soil. After several years of drought followed by heavy rains, the slab heaved unevenly, causing diagonal cracks in drywall and gaps around door frames. Remediation included installing a moisture barrier under the home's perimeter to regulate soil moisture.