# Foundation Types guides > Slab, crawl space, basement and pier-and-beam foundations: how each is built, how each fails and what repair suits it. From Foundation Repair Lab. Canonical: https://foundationrepairlab.com/types/ Last updated: 2026-11-08 ## Four foundation types, four failure modes What fails in a house depends on how it was built. A 1950s slab-on-grade in Texas and a 1920s pier-and-beam in Louisiana have different weak points, different repair economics and different warning signs. Before comparing quotes, know which type you own. | | Type | How it is built | Common failure | Typical repair | Slab-on-grade | Concrete slab poured on prepared soil, often post-tensioned | Perimeter settlement, interior voids, plumbing leaks under slab | Piers at the perimeter, slab lifting inside | Crawl space | Perimeter stem wall with piers or block, floor joists above | Footing settlement, joist rot, moisture | Piers, joist repair, drainage and encapsulation | Basement | Concrete or block walls on footings, slab floor | Bowing walls from soil pressure, wall cracks, water | Carbon fibre, anchors, waterproofing | Pier-and-beam | Concrete or wood piers supporting beams and joists | Rotten piers, shimming failure, settlement | Pier replacement, re-shimming, re-levelling ## Slab-on-grade The slab is the floor and the foundation at once. When the soil under a perimeter beam compresses, the edge of the slab drops and the brick veneer cracks in a stair-step pattern. When the soil under the middle erodes, the slab becomes unsupported and feels hollow or bouncy. Repair splits along that line: perimeter settlement gets piers driven under the beam, interior voids get foam or slurry injection. Post-tensioned slabs need a different approach again — cutting into a tensioned slab without an engineer is dangerous, and a contractor who does not ask whether the slab is post-tensioned should be shown the door. ## Crawl space A crawl space is a structural system with a moisture problem built in. The footings carry the perimeter and the interior piers; the joists carry the floor. Settlement shows up as a sloping floor or a sagging joist, and rot shows up as a soft spot near the plumbing. Repair order matters: fix drainage and vapour first, then structure. Encapsulating a crawl space without addressing a settled pier hides the problem; installing piers without fixing the moisture means the new wood rots too. The [crawl space guide](/crawl-space-foundation-repair/) walks the sequence. ## Basement Basement walls hold back soil, and soil pressure is what bows them. A horizontal crack at mid-height with a wall that has moved inward is the classic pattern. The fix depends on how far it has moved: carbon fibre for cracks and light bowing, anchors and excavation for more, rebuild for severe movement. Waterproofing is a separate trade and a separate budget. Interior drainage and a sump address water after it enters; exterior membrane and drainage address it before. Doing the structural repair without the water repair usually means doing the structural repair twice. ## Pier-and-beam Pier-and-beam lifts the house off the ground, which makes it the easiest type to re-level and the easiest to inspect. It also means the piers are the weak point: wood piers rot, concrete piers settle, shims compress and beams sag between supports. Re-levelling a pier-and-beam house is genuinely possible — jacking, re-shimming and replacing piers — and it is usually cheaper than a slab repair of similar extent. The trap is a contractor who re-shims without addressing why the pier moved. The [problems hub](/problems/) maps symptoms to each type, and the [repair methods hub](/repairs/) explains what each fix does. If you are still deciding whether to repair or replace, the [comparison hub](/compare/) prices both. ### Which foundation type is best? For repair economics, pier-and-beam is the easiest to inspect and re-level. For energy and moisture, a well-drained slab or a sealed crawl space performs better. "Best" depends on climate and soil, not on a single ranking. ### How do I know which type I have? Look for a crawl space access hatch, a basement stair, or the slab edge at an exterior door. A home inspection report usually names it; a $400 engineer visit confirms it. ### Can a slab foundation be re-levelled? Yes, within limits. Foam or slurry injection lifts a settled slab by inches, not feet, and it does not restore bearing capacity. Significant perimeter settlement needs piers. ## Guides in Foundation Types - [Basement Foundations: Types, Costs, and Repairs](https://foundationrepairlab.com/basement-foundation/) - [Basement Foundation Repair: Walls, Footings, Water](https://foundationrepairlab.com/basement-foundation-repair/) - [Concrete Block Foundations: What to Expect](https://foundationrepairlab.com/block-foundation/) - [Concrete Slab Foundation Repair: A Field Guide](https://foundationrepairlab.com/concrete-slab-foundation-repair/) - [Crawl Space Foundations: Types, Problems, and Repair Costs](https://foundationrepairlab.com/crawl-space-foundation/) - [Floating Slabs: What They Are and Repair Costs](https://foundationrepairlab.com/floating-slab/) - [Footing vs Foundation: What's the Difference](https://foundationrepairlab.com/footing-vs-foundation/) - [Grade Beams and Their Role in Foundation Repair](https://foundationrepairlab.com/grade-beam/) - [Monolithic Slab Construction Explained](https://foundationrepairlab.com/monolithic-slab/) - [Pier and Beam Foundations Explained](https://foundationrepairlab.com/pier-and-beam-foundation/) - [Post-Tension Slabs and Repair Limits](https://foundationrepairlab.com/post-tension-slab/) - [Slab Foundations: How They Fail](https://foundationrepairlab.com/slab-foundation/) - [Slab Foundation Repair: Cracks, Voids, and Lifting](https://foundationrepairlab.com/slab-foundation-repair/) - [Stem Wall Foundations: Types, Problems, and Repair Costs](https://foundationrepairlab.com/stem-wall-foundation/) - [Stone Foundations in Older Houses](https://foundationrepairlab.com/stone-foundation/)