Crawl Space Foundation Repair Cost by Problem Type

Updated September 2026 · Home Project Resources

Crawl space foundation repair cost is driven by which part failed, how many support points need work, how tall the crawl space is, and whether moisture caused the damage in the first place. A dozen new support jacks under a sagging girder is a one or two day job. Underpinning a settling perimeter footing with driven piers is engineered work on a different scale entirely.

The order matters as much as the repair. Fix the water first, then the structure, then seal the space. Repairing rotted framing while the ground under it is still wet just buys you a few years.

Updated September 2026

A note on numbers. You will find specifications, quantities and quote line items here, not dollar figures. Foundation repair pricing varies wildly by soil type, region and contractor, and any number would go stale fast. Use the bid comparison checklist near the end on three written quotes.

Most crawl space work is priced per square foot of floor area or per support point. Measure the footprint with the free Square Footage Calculator before estimators arrive, so you can check the area on every bid against the same number.

The five failures people call "crawl space foundation repair"

They are genuinely different problems with different fixes, and lumping them together is how homeowners end up comparing bids that are not comparable.

Notice that only two of the five are truly structural. A large share of quotes labeled foundation repair are really moisture jobs with framing damage as a side effect, and that is good news for the scope.

If your house sits on a basement rather than a crawl space, the wall-specific version of this problem is covered in basement wall repair cost by crack type and fix.

What drives crawl space foundation repair cost

1. Number of support points, not square footage. Structural work prices per pier, per jack, or per linear foot of beam. Twelve new support columns is roughly four times six. The area of the crawl space barely enters into it.

2. Whether the fix is engineered. Push piers and helical piers driven to load-bearing soil require a design, often a stamped letter from a structural engineer, and specialized equipment. That is a category change, not an increment.

3. Access height. A 42 inch crawl space is workable. An 18 inch crawl space means a crew working on their backs, dragging every piece of lumber and every bag of concrete in through a 24 by 30 inch access door. Some contractors price a low crawl at a straight multiplier for exactly this reason.

4. Entry size and location. An exterior door with a clear path is best. An interior hatch inside a closet means every bucket of spoil comes out through your house.

5. How wet it is. Standing water means the crew has to dewater before they can start, and it usually means the repair scope grows once they can see the framing.

6. What has to be removed and replaced. Old fiberglass batts hanging off the subfloor, failed ductwork, contaminated debris, and rotted framing all have removal and disposal costs attached.

Code clearances and specs worth knowing

These are the numbers an inspector uses, and they are useful for reading a bid.

• Clearance under floor joists: 18 inches minimum, and 12 inches under girders and beams. If a proposed repair adds framing that drops below this, ask how it will be handled.
• Ventilation, vented crawl: 1 square foot of net free vent area for every 150 square feet of crawl space area, reduced to 1 per 1,500 square feet where a Class I vapor retarder covers the ground.
• Ground vapor retarder, minimum: 6 mil polyethylene, seams overlapped at least 6 inches.
• Encapsulation liner, typical practice: 12 to 20 mil reinforced liner, seams overlapped 12 inches and taped, run up the walls to within about 3 inches of the sill so termite inspections stay possible.
• Support column footings: poured concrete footings sized for the load and bearing on undisturbed soil. A common residential detail is a 24 by 24 by 8 inch footing under a 16 by 16 inch block pier, but load and soil decide the real size.
• Wood moisture content: below 20 percent. Fungal decay needs sustained moisture above roughly that threshold, so a moisture meter reading is a genuine diagnostic, not a sales prop.
• Floor deflection target: L/360 for a finished floor, meaning a 12 foot span should deflect no more than about 0.4 inches under design load.

The International Residential Code text behind most of these is published by the ICC, and your local building department can tell you which edition and amendments apply to you.

Structural repairs, in order of severity

Adding support: piers, columns and jacks

The most common crawl space repair. A sagging girder gets new intermediate support, usually adjustable steel columns on new poured footings, spaced to shorten the beam's unsupported span. Typical girder support spacing in residential framing runs 6 to 8 feet, and a sagging beam very often turns out to be sitting on piers that were spaced too far apart from the beginning, or on piers that have settled.

The critical detail is the footing. An adjustable steel jack set directly on crawl space dirt will sink, and you will be back in five years. Every new support point needs a real footing bearing on undisturbed soil below the frost line where applicable.

Lifting is slow work. Raising a settled beam faster than roughly 1/8 inch per week is how drywall upstairs cracks and doors stop closing. Any contractor promising to level your floors in an afternoon is telling you something about how the job will go.

Sistering and replacing framing

Rotted or split joists are repaired by fastening a new full-length member alongside the damaged one, bearing on the same supports at both ends. A sister that stops short of the bearing points is decoration, not structure. Nailing or bolting patterns matter, and so does bringing the sister tight to the subfloor so it actually picks up load.

Sill plates and band joists are the classic rot locations because they sit closest to grade and get wet from splashback and poor grading. Replacing a sill plate means temporarily supporting the wall above it, which is real work.

Underpinning with piers

When the perimeter footing itself has settled, no amount of interior support fixes it. Push piers are hydraulically driven steel sections pushed to load-bearing strata using the weight of the house. Helical piers are screwed in and can be torque-verified, which makes them useful for lighter structures and additions. Depths vary enormously with soil, commonly 10 to 30 feet, occasionally far more.

This work is engineered. Expect a structural engineer's involvement, a permit, and inspections at pier installation. Be skeptical of any bid for underpinning that includes neither.

If you are unsure whether the wall above a sagging area is even carrying load, how to tell if a wall is load bearing will help you frame the question before you call anyone.

Moisture: the cause behind most of the damage

Wood in a crawl space rots because it stays wet. Fix the water and the structural repairs actually last.

Work the list from outside in:

1. Gutters and downspouts. Extend discharge 6 to 10 feet from the foundation. One inch of rain on a 1,000 square foot roof is about 623 gallons, and dumping that at a crawl space wall is the most common single cause of a wet crawl.
2. Grade. Soil should fall about 6 inches over the first 10 feet away from the house.
3. Interior drainage. A perimeter drain inside the crawl, tied to a sump or daylight, for ground water that arrives from below.
4. Ground cover. A vapor retarder or full encapsulation liner over 100 percent of the soil.
5. Air. Either vent it per code, or seal it and condition it. The half-measure of a partly sealed, partly vented crawl is the worst outcome, because in humid climates outside air entering a cool crawl condenses on the framing.
6. Dehumidification. In a sealed crawl, a dedicated unit sized around 70 pints per day, drained to a sump or a condensate pump, holding relative humidity at 50 to 55 percent.

Insulation strategy follows that decision. In a vented crawl, insulation goes in the floor above. In a sealed and conditioned crawl, it goes on the walls instead and the floor stays uninsulated. Getting this backward is common. Check target values in the R-value insulation chart and the material options in types of insulation before anyone installs anything, and note that fiberglass batts stapled under a subfloor in a damp crawl fall down within a few years and hold water while they are up there.

If the same water problem also affects a basement portion of the house, the method comparison in basement waterproofing cost applies directly.

Worked example: 1,150 sq ft crawl space with a sagging center girder

A 1960s ranch on block piers. The living room floor slopes noticeably toward the middle of the house, a hallway door drags, and there is a soft spot near the back wall. Crawl clearance measures 32 inches at the access and 24 inches at the low corner.

What the inspection found. The center girder is a built-up wood beam carried on block piers spaced 11 feet apart, which is well beyond the 6 to 8 feet the beam size wants. Three piers have settled and two have shims stacked over an inch high. The band joist along the back wall reads 28 percent moisture content and is spongy for about 9 feet. The ground is bare soil with a torn 4 mil sheet over maybe 60 percent of it. Two downspouts discharge at the wall.

Sequence. Water first, structure second, encapsulation last.

The two numbers that mattered most. Cutting the girder span from 11 feet to 5.5 feet is what actually fixed the floor, and it took 7 support points, not 20. And the liner area is 1,150 square feet of floor plus wall coverage, which is why measuring the footprint before the estimate is worth doing: liner is quoted by area, and an inflated area is the easiest place for a bid to drift.

Note also what is not on the list. No piers, no underpinning, no engineer. The perimeter footing had not moved. A contractor who opens with underpinning on a job like this is selling the wrong product.

Permits, engineers and licensed work

Structural repairs to a foundation require a permit in nearly every jurisdiction, and underpinning almost always requires a stamped design from a licensed structural engineer plus an inspection while the piers are exposed. Encapsulation and vapor barrier work often does not require a permit, though sealing crawl space vents changes the building's ventilation strategy and some jurisdictions want that reviewed.

Two safety items that are not negotiable. First, if a fuel-burning appliance vents into or draws combustion air from the crawl space, sealing that crawl without addressing combustion air is dangerous, and it is a job for a licensed mechanical contractor. Second, mold remediation above roughly 10 square feet of visible growth is regulated in some states and should be handled by a remediation contractor, not folded into a carpentry bid.

Get an independent structural engineer if a contractor recommends piers. An engineer who is not selling the repair is the cheapest second opinion in the entire home repair world, and their report becomes the specification that all three bids have to price against.

How to compare crawl space repair bids

1. Make every bid price the same scope. If one includes underpinning and two do not, you are not comparing anything.
2. Ask for the diagnosis, in writing, separate from the proposal. What failed, why, and what evidence supports it.
3. Check the footing detail for every new support column. Size, depth, and bearing on undisturbed soil should be stated.
4. Ask for the lift schedule if any leveling is included. A slow schedule protects the finishes upstairs.
5. Verify the liner specification: mil thickness, reinforcement, seam overlap and tape, wall termination height, and whether it is mechanically fastened.
6. Confirm the water plan comes first. A bid that seals a wet crawl without addressing drainage is going to fail.
7. Read the warranty transfer terms. Foundation warranties are often transferable and often require annual inspections to stay valid.
8. Ask who pulls the permit and who schedules inspections. Then confirm with the building department that the permit was actually issued.

FAQ

How do I know if my crawl space problem is structural or just moisture?

Look at what is moving versus what is decaying. Sloping floors, sticking doors, stair-step cracks in exterior brick, and gaps opening at trim point to movement. Musty smell, high humidity, surface fungus, fallen insulation and soft spots point to moisture with framing damage. A moisture meter reading above 20 percent in the framing confirms the second. Many houses have both, and the water gets fixed first either way.

Is crawl space encapsulation worth it?

In humid climates, generally yes. A sealed crawl with a reinforced liner and a dehumidifier holds framing moisture down, stops the soil from feeding humidity into the house, usually improves comfort on the floor above, and makes the space usable for storage and service access. In a dry climate with a code-vented crawl that has stayed dry for decades, a good ground vapor retarder alone may be all you need.

Can I level my floors with jacks myself?

Adding a temporary post under a bouncy spot is within reach for a careful homeowner, provided it sits on a real footing and you are not carrying a load path you do not understand. Actually lifting a settled structure is not a DIY project. Lifting too fast cracks drywall, breaks tile, jams doors and windows, and can crack a masonry chimney. If a beam is carrying a bearing wall above, get an engineer involved.

What is the difference between push piers and helical piers?

Push piers are hydraulically driven into the soil using the weight of the structure as the reaction force, so they suit heavier buildings. Helical piers are screwed in with a torque motor, and the installation torque correlates with capacity, which lets the installer verify each pier as it goes. Helicals work well for lighter structures, additions and porches. Both are engineered, permitted work.

How much clearance should a crawl space have?

Codes generally require 18 inches under floor joists and 12 inches under girders and beams, which is the working minimum for inspection and service. Anything under about 24 inches makes repair work slow and expensive, and some contractors add a low-clearance factor for exactly that reason. Excavating a crawl space deeper is possible but it is a significant structural job because it affects footing bearing depth.

Should crawl space vents be open or sealed?

Pick one strategy and commit. A vented crawl needs 1 square foot of net free vent area per 150 square feet of area, or per 1,500 square feet with a Class I ground vapor retarder. A sealed crawl gets a full liner, sealed vents, air sealing at the rim, wall insulation and a dehumidifier. In humid summers, partial venting is actively harmful because warm moist air condenses on cool framing. Never seal a crawl that supplies combustion air to an appliance without a mechanical contractor addressing it.

Does a crawl space repair need a permit?

Structural repairs almost always do, and underpinning nearly always requires an engineer's stamp plus an inspection with the piers still exposed. Encapsulation frequently does not, though sealing vents can trigger review in some jurisdictions. Unpermitted structural work is a recurring problem at resale, because buyers' inspectors find it and lenders ask about it.

How long does crawl space foundation repair take?

Adding support columns under a girder is typically one to three days. Sistering joists and replacing a section of band joist adds a day or two. Full encapsulation of a 1,000 to 1,500 square foot crawl usually runs two to three days. Pier underpinning is a week or more and involves excavation at each pier location plus inspection holds.

Related: Measure the footprint with the Square Footage Calculator and check footing concrete volumes with the cubic yard calculator. Then work through the water with basement waterproofing cost, rule out wall movement using basement wall repair, and choose the right insulation strategy with types of insulation and the R-value insulation chart.