Sagging Floors Over an Atlanta Crawl Space: Girders, Joists and Posts
When a floor dips or bounces in a house built over a crawl space, the problem is often the wood framing under it rather than the foundation itself. Crawl space repair puts support back where the floor has lost it.
Fixr's September 2026 guide prices sagging floor repair at $1,000–$8,500. Sistering a joist runs $150–$325 each, replacing one $500–$2,500, and replacing a main support beam $2,000–$10,000. Fixr's crawl space repair guide (2025) lists wood rot repair at $750–$5,000.
Where a sagging floor usually starts
- Piers too far apart. The girder sags between supports, and the floor follows it.
- A settled or crumbling pier. Brick or block piers on a thin footing can sink or lean over decades.
- Rot at the girder or sill. Wood that stays damp softens where it meets masonry, often below a leaking door or under a bathroom.
- Cut or notched joists from old plumbing or duct work.
- Undersized framing that was adequate once but now carries a heavier kitchen, tub or bookcase.
What does crawl space repair involve?
Supplemental posts: adjustable steel posts set on new concrete footings under the girder, shortening the span and taking out the dip a little at a time. Sistering: bolting a new joist alongside a weak one. Girder or sill replacement: shoring the house temporarily while rotted timber is cut out and replaced. Rebuilding a pier that has sunk or cracked. A sound plan names each post location and footing size, and raises the floor gradually rather than all at once.
Dry the crawl space, then fix the wood
Rotted framing has a water source. Atlanta averages 50.43 inches of precipitation a year with no dry season (NOAA 1991–2020 normals), so a gutter spilling at the foundation, soil sloping toward the vents or a plumbing drip can keep wood wet year round. Ask the specialist where the moisture comes from and how the repair deals with it. A ground cover, drainage correction or ventilation change may be part of the answer; sealing the whole crawl space is a separate project with its own price.
Before you go under the house
Look from the access door with a flashlight rather than crawling deep: wiring, nails and pests make crawl spaces hazardous. Note any wood that looks dark or wet, posts that lean, and water standing on the ground. The EPA places Fulton County in Radon Zone 1, so a radon test is sensible after any crawl space work. Compare the typical price of each fix in the foundation and crawl space cost table.
Questions homeowners ask
Can I just add a jack post myself?
A temporary post can stop a floor getting worse, but a permanent one needs a proper footing under it and a plan for how far to raise the floor. Jacking too quickly can crack plaster, tile and drywall above, so let a specialist size the footing and the lift.
Tell us what the house is doing
A sentence is enough: where the crack is, which floor dips, or what you saw under the house. One independent specialist who works on Atlanta foundations and crawl spaces will phone you to talk it through and, if it helps, arrange a visit.