A crawl space encapsulation quote is a bundle: a heavy plastic liner, surface prep, sealed vents, usually a dehumidifier, and sometimes drainage or insulation. Two quotes with the same headline price can include very different work, so it helps to know which lines you are paying for and what moves each one.
The EPA says the best way to control mold growth is to control moisture, and moisture control is what these lines are for. This guide uses the unit prices in the EstiCube crawl space calculator. They are national planning numbers, not a quote, so replace them with the figures from your own estimates.
What the price is made of
The calculator's default job is a 50 by 30 foot crawl space (1,500 square feet of floor) with 3-foot foundation walls, a 12 mil liner, damp conditions, 6 vents and a dehumidifier. The liner covers the floor plus the walls: 1,500 square feet of floor plus 480 square feet of wall is 1,980 square feet. Every line below is rounded to whole dollars.
| Line | How it is priced | Cost |
|---|---|---|
| Vapor barrier (12 mil) | 1,980 sq ft at $2.00 | $3,960 |
| Cleanup and surface prep | 1,500 sq ft at $0.75, times 1.3 for damp | $1,463 |
| Vent sealing | 6 vents at $65 | $390 |
| Dehumidifier | Flat charge | $2,200 |
| Total | $8,013 |
How liner thickness changes the total
The liner is priced per square foot of floor and wall: $1.60 for 10 mil, $2.00 for 12 mil and $2.80 for 20 mil reinforced. Holding everything else at the default, the totals are $7,221 with a 10 mil liner, $8,013 with a 12 mil liner and $9,597 with a 20 mil liner. That is $4.81, $5.34 and $6.40 per square foot of floor.
Going from 12 mil to 20 mil adds $1,584 on this space. Whether the heavier liner is worth it depends on how the space will be used and how much foot traffic it sees, so ask the contractor why they recommend the thickness they quote.
How wet the space is
A wetter crawl space takes more cleanup and prep before the liner goes down. The calculator multiplies the prep line by 1.0 for a dry space, 1.3 for damp or musty and 1.8 for standing water after rain. On the default job the prep line is $1,125 dry, $1,463 damp and $2,025 with standing water, so the totals are $7,675, $8,013 and $8,575.
That multiplier only covers extra prep. Water that comes in repeatedly is a separate problem, and the EPA's advice is to clean up the mold and eliminate the sources of moisture. Drainage and a sump pump are priced as their own lines for that reason.
Optional add-ons and what each costs
These are off by default. Each is shown here added alone to the $8,013 default job:
- Rigid foam wall insulation: 480 square feet of wall at $3.50, or $1,680, for a total of $9,693.
- Interior drain tile: 160 linear feet of perimeter at $28, or $4,480, for a total of $12,493.
- Sump pump: a $1,800 flat charge, for a total of $9,813.
- Dehumidifier: already in the default at $2,200. Turning it off drops the default to $5,813.
Worked examples, including size
Size works through the floor and wall area, while the dehumidifier and vent sealing are fixed amounts. A smaller 30 by 20 foot space with the other defaults costs $4,975, or $8.29 per square foot, because $2,590 of the job (the dehumidifier and vent sealing) does not shrink with the floor. A larger 70 by 40 foot space costs $12,240, or $4.37 per square foot.
A dry 50 by 30 foot space with wall insulation added comes to $9,355: $3,960 liner, $1,125 prep, $390 vent sealing, $2,200 dehumidifier and $1,680 insulation. A damp space with the liner and vent sealing only, no dehumidifier, is $5,813.
The full scope with standing water, wall insulation, drain tile and a sump pump is $16,535. The calculator also applies a $2,500 minimum job, so very small spaces with few options are priced at that floor. You can reproduce each of these by setting the same dimensions and options.
What to check when comparing quotes
Compare scope before price. Ask each contractor:
- Whether the liner runs up the walls and how many square feet and which thickness the price covers.
- Whether vent sealing, a dehumidifier, insulation, drainage and a sump pump are included or priced separately.
- How the cleanup and prep charge changes with the condition of the space.
- What the warranty covers, and whether the dehumidifier is part of it.
Run your numbers with the Crawl Space Encapsulation Cost Calculator
Change any unit price to match your quote and see every line item add up. It is free, needs no sign-up and works on your phone.
Open the Crawl space calculatorFrequently asked questions
How much does crawl space encapsulation cost?
In this calculator the default 1,500 square foot job with a 12 mil liner, damp conditions, 6 vents and a dehumidifier is $8,013, or $5.34 per square foot of floor. Your size, condition and scope change that, so use your own measurements.
Why does the liner cost use more square feet than my floor?
The calculator prices the liner across the floor and the foundation walls. For a 50 by 30 foot space with 3-foot walls that is 1,980 square feet of liner against 1,500 square feet of floor.
Is a dehumidifier part of encapsulation?
It is included in the calculator's default at $2,200, and you can switch it off. Contractors differ on whether it is standard, so check what each quote lists.
Are insulation, drainage and a sump pump included?
Not by default. Wall insulation adds $1,680, interior drain tile adds $4,480 and a sump pump adds $1,800 on the default job. They are separate lines because not every crawl space needs them.
What is the minimum job price?
The calculator applies a $2,500 minimum. If the lines add up to less, the total is raised to $2,500, which mostly affects very small spaces with few options.
Sources
- Mold — U.S. Environmental Protection Agency
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