Crawl Space Encapsulation Cost Calculator

About $6,275 for a full encapsulation of a 1,000 square foot crawl space, which is $6.28 a square foot and includes 20 mil liner up the walls, sealed vents and a dehumidifier. A vapor barrier laid on the ground alone is $2,750. Encapsulation over drainage matting with a pump, for a space that takes standing water, is $8,850. A 1,600 square foot crawl space is $8,500 for the full package, or $5.31 a square foot, because the fixed costs spread.

A vapor barrier is liner laid over the ground with the seams taped. An encapsulation takes the liner up the walls on a termination bar and seals it to the masonry, seals the vents, details the rim joist and adds a dehumidifier. The first is a real improvement over bare dirt and costs less than half as much, and it is sold as an encapsulation constantly because the word carries a price the work does not. All four of those differences are checkable on a written quote.

Reinforced 20 mil if you can, which is what most reputable contractors fit and warrant for 25 years, at $1.50 to $2.50 a square foot installed. Reinforced 12 mil is a legitimate budget choice at $1.00 to $1.75. Six mil builder's sheet should not be in a quote: it is what is already down there, and it failed because anyone who crawls over unreinforced plastic tears it. "Reinforced" matters as much as the number — it means a scrim woven into the plastic, which stops a tear running across the whole sheet.

Yes. Sealing stops new moisture arriving from the ground and the outside air, and it also removes the ventilation that used to carry some of the existing moisture away — so a sealed crawl space without a dehumidifier is a sealed damp crawl space. Budget $800 to $2,000 installed, often quoted as a flat add-on near $1,800. Look for 70 to 100 pints a day for a typical space, a condensate pump draining somewhere permanent rather than a bucket, and a humidistat you can read without crawling under the house. Target 50 to 55% relative humidity.

Always, and reversing that order is the expensive mistake here. If the crawl space takes liquid water — puddles after rain, a patch that never dries, water running in at the footing — a liner laid over it traps the water underneath where it is invisible and keeps the ground saturated. The space reads dry while the wood stays wet, and it surfaces years later as a floor that gives. Water first means drainage matting and a perimeter channel under the liner feeding a pump, which is the $8,850 package. If the water is arriving from outside, fixing the grading or the downspouts is cheaper than either.

Not much on its own. Encapsulation is a moisture job: it stops water vapor and air coming up from the ground and in through the vents. A cold floor is a thermal problem and it needs insulation, which is a different trade at a different price. The two are frequently sold together and the right order is moisture first, because insulating a damp crawl space puts batts in a wet place. Sealed crawl spaces do tend to make a house measurably easier to heat and cool, but treat that as a side effect rather than a payback.

More than anything else on the quote, which is why it is a control on this calculator rather than a footnote. Over three feet a worker can kneel, turn around and carry a roll of liner, and the job runs about 10% cheaper. At two to three feet they are crawling, which is what most quotes assume. Under two feet they are on their side dragging material and every hour is slower — about 25% more. Measure from the dirt to the bottom of the joists at the worst point, not at the hatch, and expect some contractors to decline the work under about eighteen inches.

It is a separate job and it belongs before the liner, not under it. A contractor proposing to seal over visible growth is selling you a problem you can no longer inspect. Remediation is priced on its own and usually runs from a few hundred to a couple of thousand dollars in a crawl space. The surcharge on this page for debris or mold covers clearing and cleaning the space so the liner can be laid, not the remediation itself. If the joists are already soft rather than just stained, that is structural repair and it is carpentry.

No, and it is the point. Vents were intended to carry moisture out, and in a humid climate they do the opposite for much of the year: warm damp outside air meeting cool crawl space surfaces condenses on them. Current building codes allow unvented crawl spaces where there is a sealed ground cover and either conditioned air or a dehumidifier, which is what an encapsulation provides. The one thing to confirm is combustion: if a furnace or water heater draws its air from the crawl space, sealing it needs a sealed-combustion appliance or a dedicated air supply.

The liner itself should last decades, and 20 mil reinforced product is commonly warranted for 25 years. What fails first is everything mechanical and everything that gets disturbed: a dehumidifier is a 10 to 15 year appliance, a condensate pump less, and the liner gets torn by anybody who works under the house afterwards — a plumber, a cable installer, a rodent. Ask for the tape and a repair patch kit to be left on site, and check the humidistat reading a couple of times a year rather than waiting for a smell.