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Wet crawl space: what to fix first
Fix the water source before the crawl space. Most wet crawl spaces are gutters and grading sending roof water under the house, or a plumbing or HVAC condensate leak; those cost hundreds, not thousands. Encapsulation (vapor barrier, sealed vents, dehumidifier) is the right finish on a crawl space that is dry from outside, and a waste on one that isn't.
When it is serious
- Standing water after rain that does not drain within a day
- Wood moisture high enough for visible fungus on joists
- Sagging insulation, rusted ductwork, a musty house
- Efflorescence or a water line on interior piers
When it is usually cosmetic
- Slightly damp soil in a humid climate with dry framing
- Old, torn vapor barrier with no moisture problem
What the soil under your address does to this answer
Somewhat poorly and poorly drained soils, hydrologic group C and D, and a seasonally high water table make a crawl space wet from below regardless of what the gutters do; on those, a perimeter drain and sump are part of the fix. On well-drained soil, water under the house almost always came from above.
How much does crawl space repair cost?
It depends on which of three jobs is being quoted, and a good quote says which. Fixing the water source (gutters, downspout extensions, grading, a leak) is the cheapest and comes first. Drainage and waterproofing have published national ranges, cited in the table below. Structural work under the house, new piers, sistered joists, a replaced beam, is priced by the item, and encapsulation is priced by the square foot; we cite no published range for either and will not invent one.
Comparing crawl space repair companies
The same rules as a foundation bid. Ask that the water source be identified and fixed first, and priced separately from anything structural. Ask for the scope by item: which piers, which joists, how many feet of drain, what the sump discharges to. Ask what the dehumidifier and vapor barrier warranty actually covers and for how long. A company that quotes encapsulation before the crawl space is dry from outside is selling the finish, not the fix.
Check the soil under an address
USDA soil survey, read for the top 60 inches under the address. Free, no account, nothing is sent to a contractor.
Usually 1–3 seconds. The USDA service occasionally takes longer.
What the repair costs, if it is one
| Repair | Published range | When it's the right tool | Source |
|---|---|---|---|
| Crack repair (epoxy / polyurethane injection) | $250–$800 per crack | Hairline or non-moving cracks, moisture entry. Not a fix for movement. | Bob Vila — How Much Does Foundation Repair Cost?, updated 2024-05-29 |
| Foundation sealing / waterproofing | $2,300–$7,300 per job | Water entry in a basement or crawl space. Usually paired with drainage, not piers. | This Old House — Foundation Repair Cost, updated 2026-03-06 |
| Drainage system | $2,800–$6,500 per job | Often the first, cheapest fix on wet or moderately expansive soil. | Bob Vila — How Much Does Foundation Repair Cost?, updated 2024-05-29 |
What to do next
Check the drainage class and water-table depth for the address below. Walk the exterior in rain and watch where the water goes. Then price the fixes in this order: gutters and grading, leaks, drainage, encapsulation.
Questions people ask
How much does crawl space encapsulation cost?
We do not cite a published range for encapsulation and will not guess one; it is quoted per square foot and depends on crawl-space size and whether a dehumidifier and sump are included. What we do cite is in the table below: drainage systems and foundation waterproofing. Get the water source fixed and priced first.
Is a wet crawl space a foundation problem?
It becomes one. Wet soil under interior piers lets them sink, and on expansive clay it drives the swelling. Dry it before deciding on structural work.
We are not engineers and this is not an engineering opinion. We report public soil-survey data and published price ranges. Nothing here states that a specific house is or is not structurally sound; a licensed structural engineer who has seen the house can.