Crawl space repair covers the structure under the floor rather than the foundation walls around the outside — the piers, girders, joists and subfloor that actually hold your floors up. In older Birmingham neighborhoods this is where a large share of what people call foundation problems actually live, and it is usually a smaller and cheaper job than perimeter underpinning.
The Signs From Upstairs
Floors that bounce or feel springy when you walk across them. Floors that slope toward the center of the house rather than toward an outside wall. Gaps opening between the floor and the baseboard. Interior doors that stick at the top on one side. Tile grout cracking in a straight line across a room.
A slope toward the middle of the house is a strong indicator that the problem is under the floor rather than around the perimeter, because interior piers carry the center girder and there is nothing else down there to drop.
What Fails Under a Birmingham House
Masonry piers built dry-stacked without mortar, which many mid-century homes here have, gradually shift and lose bearing. Wood shims placed on top to make up height rot away or compress, and the girder drops by the thickness of the shim.
Piers set on inadequate footings, or on no footing at all, punch down into clay that softens when it gets wet.
Girders and joists soften from long-term moisture. Termite damage is also a genuine and common factor in this part of Alabama and needs identifying before anything is rebuilt on top of it.
Previous repairs done badly. Stacked concrete blocks with no mortar, car jacks left in place permanently, and timber posts sitting directly on dirt are all things that turn up regularly.
How It Is Put Right
New footings poured to a size that suits the load and the soil, rather than reusing whatever the pier was standing on.
Adjustable steel jack posts or properly built masonry piers to replace what failed, set on those footings and shimmed with steel rather than wood.
Sistering or replacing joists and girders where the timber has lost section to rot or insects. Sistering — bolting a sound member alongside the damaged one — is normally cheaper and less disruptive than full replacement where the damage is localized.
Gradual lifting where the floor has dropped. This should be done slowly, over multiple visits in bad cases, because raising a floor quickly cracks everything attached to it.
Fix the Cause, Not Just the Symptom
Rebuilding a pier under a girder that rotted because the crawl space is wet will buy you time and nothing more. Whatever water is getting in — surface drainage, a plumbing leak, condensation from vented humid air — needs dealing with as part of the job, otherwise you are scheduling the same repair again.
That is why crawl space repair and moisture control are usually quoted together, and why a proposal that ignores the water is worth questioning.