Crawl Space Encapsulation Cost Calculator

With the defaults, a 50 by 30 ft crawl space with 3 ft walls, a 12 mil liner, damp conditions, six sealed vents and a dehumidifier comes to $8,013, or $5.34 per sq ft of floor. The liner is the biggest line at $3,960, followed by the $2,200 dehumidifier, $1,463 for cleanup and prep and $390 for vent sealing.

Size matters, but not in a straight line, because the dehumidifier is a flat cost. A 25 by 20 ft space (500 sq ft) with four vents comes to $4,488, which is $8.98 per sq ft. A 40 by 30 ft space with six vents comes to $7,000, or $5.83 per sq ft, and a 60 by 40 ft space with eight vents comes to $11,060, or $4.61 per sq ft. The smallest spaces hit the $2,500 minimum job charge when the extras are left out.

The calculator prices a typical installation. Access, the amount of debris to remove, local labor rates and the brand of equipment all move a real quote, so use the pricing section to enter the numbers from a contractor and compare bids on the same footing.

A plain vapor barrier is a sheet of plastic laid over the dirt floor to slow moisture coming up from the ground. Encapsulation goes further. The liner is a thicker, durable material that covers the floor and climbs the foundation walls, the seams are overlapped and sealed, the vents are closed off and the space is conditioned, usually with a dehumidifier. The aim is to treat the crawl space as part of the building envelope instead of an open, vented cavity.

That is why this calculator measures liner area as floor plus wall area. At the default size that is 1,980 sq ft rather than 1,500 sq ft. The liner thickness you pick changes the price: a 10 mil liner brings the default job to $7,221, 12 mil is $8,013 and a 20 mil reinforced liner is $9,597. Thicker liners resist tears from foot traffic when someone has to get under the house to service equipment.

Raising the wall height also adds liner. At 4 ft walls instead of 3 ft the default job rises from $8,013 to $8,333, because the liner area grows from 1,980 to 2,140 sq ft.

Controlling moisture is the core of the job. The EPA says moisture control is the key to controlling mold, so the point of sealing the vents and adding a dehumidifier is to keep humid outdoor air from wetting the space and to dry the air that is already there. Sealing costs $65 per vent in the calculator, so six vents add $390.

The dehumidifier is a $2,200 flat allowance. Leaving it out drops the default job from $8,013 to $5,813, but a sealed space with no way to remove moisture may not stay dry, so check with your installer before taking it off the list. A dehumidifier also runs on electricity, so it adds an ongoing running cost that this one-time estimate does not include.

Wall insulation is optional, and how much is worthwhile depends on your climate and how the space is used, so ask your contractor. In the calculator, rigid foam on the foundation walls is $3.50 per sq ft of wall, which is $1,680 on the default 480 sq ft of wall and brings the total to $9,693.

A damp crawl space and one that holds standing water are different problems. The condition setting multiplies the cleanup and prep line: 1.0 for dry, 1.3 for damp and 1.8 for standing water. On the default 1,500 sq ft floor that is $1,125, $1,463 or $2,025, which makes the whole job $7,675, $8,013 or $8,575.

A liner and a dehumidifier will not cope with liquid water coming in. Interior drain tile along the perimeter collects it and a sump pump moves it out. The calculator charges $28 per linear foot of drain tile, so 160 LF of perimeter is $4,480, and a sump pump is an $1,800 allowance. A standing-water crawl space with both comes to $14,855 at the default size.

Fixing where the water comes from, such as gutters, downspouts and grading around the house, is usually the first step and is not part of this estimate. Encapsulation manages moisture in the space but does not replace sound drainage outside.