Crawl space work is priced by the piece: roughly $150 to $600 to sister a joist in 2026, $300 to $1,000 per added support post, $1,500 to $6,000 to replace a girder, and $5,000 to $15,000 to encapsulate, so a full job usually lands between about $5,000 and $25,000.
A crawl space fails differently from a slab or a basement, and it fails in wood rather than concrete. The foundation walls and piers hold the perimeter, girders carry the middle, joists span between them, and moisture from bare soil is what eventually takes all three. So crawl space repair is usually a structural job and a moisture job at once, and pricing only the first one is why bids come back so far apart.
The figures below are typical national ranges for 2026 and local bids govern. Access dominates the labor: a 40 inch crawl a worker can move in prices very differently from an 18 inch one they cannot.
The structural pieces, and what each runs
Get a structural engineer's evaluation before buying any of these if the floor is sagging or bouncing, commonly $400 to $1,200. Bounce is a stiffness problem; a slope across the whole floor is a support problem; they have different fixes.
- Sistering a joist (bolting a new member alongside the damaged one): roughly $150 to $600 per joist. Material is cheap and the cost is a person on their back in a crawl space. A crew day covering several joists commonly runs $1,000 to $3,000.
- Replacing a girder or main beam: roughly $1,500 to $6,000. The house has to be temporarily shored while it comes out, which is most of the price.
- Adding supports: an adjustable steel jack post on a new footing commonly runs $300 to $1,000 installed. Adding a row of them under a long span is the standard fix for a bouncy floor.
- Repairing or rebuilding masonry piers: roughly $500 to $1,500 per pier. Piers on inadequate footings settle and are a common cause of an interior floor dipping while the perimeter stays level.
- Replacing rot-damaged subfloor, rim joist or sill plate: commonly $30 to $60 per square foot in a crawl, because everything is done overhead in confined space.
- Helical piers under a crawl space foundation wall: roughly $1,500 to $3,500 each, the same as anywhere, when the perimeter itself has settled.
Moisture is usually the actual repair
Bare soil in a crawl space evaporates water into the space continuously, and warm humid air entering through vents condenses on cool framing and ducts. That is the mechanism behind almost every rotted joist, cupped hardwood floor and musty return-air smell in a house with a crawl.
A vapor barrier, meaning 6 to 10 mil sheeting laid over the soil and lapped, commonly runs $0.50 to $1.50 per square foot, so $600 to $2,000 for a typical crawl. It is the cheapest meaningful improvement available and it is missing in a surprising number of houses.
Full encapsulation is a different product: a 12 to 20 mil liner run up the walls and sealed, vents closed, rim joists insulated, and a dedicated dehumidifier added. That commonly runs $3 to $8 per square foot, or about $5,000 to $15,000 on a 1,200 to 1,500 square foot crawl. The dehumidifier alone is $1,200 to $3,000 and it is the part that does the work; a sealed crawl without one can end up wetter than a vented one.
Water, mold and the order of operations
Standing water is a drainage problem before it is a crawl space problem. Interior perimeter drain tile with a sump commonly runs $5,000 to $15,000, a sump pump on its own $1,000 to $3,000, and exterior grading and downspout work a few hundred to a few thousand. Encapsulating over a crawl that floods traps the water under the liner.
Mold remediation in a crawl commonly runs $2,000 to $8,000 depending on the area and whether wood has to be sanded or soda blasted. Remediation without fixing the moisture source is a recurring expense, so the sequence that works is: stop the water, fix the structure while access is open, then seal the ground and control the humidity.
Roughly: a vapor barrier and a few sistered joists is a $2,000 to $5,000 visit. Structural work plus encapsulation on a typical house is $10,000 to $25,000. A crawl with a failed perimeter, replaced girders, new subfloor and remediation can pass $40,000, which is the point at which converting the crawl to a slab or a basement gets priced for comparison.
Questions people ask
Is crawl space encapsulation worth it?
It depends on what the crawl is doing. Where there is measurable humidity, condensation on ducts, cupping floors or a smell in the house, sealing the ground and running a dehumidifier fixes a cause rather than a symptom and protects framing worth far more than the job. In a dry climate with a properly sheeted crawl and no water intrusion, a plain vapor barrier is usually enough.
How do you know if crawl space joists need repair?
Floors that bounce or slope, doors that stick in one part of the house, gaps opening at baseboards, and visible sag along a girder line are the signals from above. From below it is dark staining, fungal growth, soft wood that a screwdriver sinks into, insect damage, and joists that have pulled off their bearing. An inspector will photograph it; an engineer will say what it means.
Does homeowners insurance pay for crawl space repair?
Rarely. The usual causes, long-term humidity, ground water, rot and insects, are excluded as maintenance, wear or earth movement. A sudden covered event such as a burst pipe can put the resulting damage inside a policy, and that is the distinction adjusters work to: sudden and accidental against gradual.