Vapor barrier cost calculator for crawl space liners, encapsulation, under-slab sheets and walls, with rolls, a strip plan, IRC laps, pier wraps, seam tape and total labor charges.
Floor liner with its edges turned up the walls and piers wrapped to the same height.
Overlap, Piers & Tape
Price, Labor & Units
Strip Layout Plan
| Piece | Count | Width × Length | Pieces per Length |
|---|---|---|---|
| Full-width floor strips | 3 | 10 ft × 42 ft | 1 |
| Last floor strip, ripped | 1 | 3 ft 6 in × 42 ft | 1 |
| Pier wraps | 6 | 1 ft × 5 ft 10 in | 1 |
Rolls by Roll Size
| Roll | Rolls | Seam Tape | Liner Left Over |
|---|---|---|---|
| 10 × 100 ft | 2 | 164 ft | 558 sq ft |
| 12 × 100 ft | 2 | 122 ft | 979 sq ft |
| 16 × 100 ft | 1 | 102 ft | 189 sq ft |
| 20 × 100 ft | 1 | 80 ft | 600 sq ft |
| 24 × 100 ft | 1 | 70 ft | 1,005 sq ft |
| 32 × 100 ft | 1 | 38 ft | 1,821 sq ft |
Typical Cost Guide
| Item | Source | Per Sq Ft | For 1,372 sq ft |
|---|---|---|---|
| 6 mil liner, material | ThePricer estimate | $0.30-$0.70 | $412-$960 |
| 10-12 mil liner, material | ThePricer estimate | $0.70-$1.25 | $960-$1,715 |
| 20 mil liner, material | ThePricer estimate | $1.50-$2.00 | $2,058-$2,744 |
| 20 mil liner, material | Angi, Jul 2026 | $0.50-$0.70 | $686-$960 |
| Labor only | ThePricer estimate | $1.00-$3.00 | $1,372-$4,116 |
| Basic barrier, installed | HomeAdvisor | $1.35-$2.00 | $1,852-$2,744 |
| Full encapsulation, total | Angi | -- | $5,000-$15,000+ |
| Crawl space dehumidifier | Angi | -- | $800-$1,200 |
| Your estimate | This tool | $2.44 | $3,346.00 |
Step-by-Step Math
- Cover = floor 40 ft × 30 ft + run-up 140 ft × 1 ft + 6 piers × 5 ft 4 in × 1 ft = 1,372 sq ft.
- Seam laps = 6 in × 132 ft of lapped seams = 66 sq ft.
- Tape = 132 ft of laps + 32 ft where pier wraps meet the floor liner = 164 ft.
- Area method = (1,372 sq ft + 66 sq ft) × 1.1 ÷ 1,000 sq ft per roll = 1.58, rounded up to 2.
- Cut plan = 2 rolls; buy the larger count, 2.
- Tape = 164 ft ÷ 180 ft per roll = 1 roll.
- Cost = liner $1,000.00 + tape $30.00 + edge attachment $258.00 + labor $2,058.00 = $3,346.00.
- Result: 2 Rolls to Buy.
Vapor Barrier Cost Calculator Totals for a 40 × 30 ft Crawl Space
A 40 × 30 ft crawl space lined with 6 mil polyethylene, run 12 in up the walls and wrapped around six piers, covers 1,372 sq ft and costs about $3,346 installed at sample prices. That is $1,030 of liner and tape, $258 to attach and seal the edges and $2,058 of labor.
The floor is only 1,200 sq ft of that vapor barrier cost calculator total. The 12 in run-up along the 140 ft perimeter adds 140 sq ft, and six 16 × 16 in piers wrapped 12 in high add 32 sq ft more.
L and W are the crawl space length and width, u is the run-up height on the walls, np is the number of piers and p is the distance around one pier. Every foot of run-up on a 40 × 30 ft space adds 140 sq ft of liner to a vapor barrier cost calculator estimate.
| 40 × 30 ft crawl space | Basis | Cost |
|---|---|---|
| 6 mil liner | 2 rolls of 10 × 100 ft at $0.50 per sq ft | $1,000.00 |
| Seam tape | 164 ft, 1 roll of 180 ft at $30 | $30.00 |
| Edge attachment | 172 ft of termination bar, fasteners and sealant at $1.50 | $258.00 |
| Labor | 1,372 sq ft covered at $1.50 | $2,058.00 |
| Total | $2.44 per sq ft covered | $3,346.00 |
The prices are sample vapor barrier cost calculator inputs, not quotes. ThePricer's 2025 crawl space vapor barrier cost guide cites HomeAdvisor at $1.35 to $2.00 per sq ft for a basic barrier installed, which puts this floor at $1,620 to $2,400.
Liner is sold by the roll, so you pay for 2,000 sq ft even though 1,372 sq ft goes down. The 558 sq ft left over is useful for patches and pier repairs, but it belongs in any vapor barrier cost calculator material line.
Crawl Space Vapor Barrier Price by Size
A 1,000 sq ft crawl space costs about $3,020 with 6 mil liner at the same sample prices, and a 2,000 sq ft space about $5,200. Labor is the larger share every time, because it is paid on every square foot covered while liner comes in whole rolls.
| Crawl space | Floor | Area covered | 10 × 100 ft rolls | Seam tape | Total at sample prices |
|---|---|---|---|---|---|
| 40 × 25 ft | 1,000 sq ft | 1,162 sq ft | 2 | 122 ft | $3,016 |
| 40 × 30 ft | 1,200 sq ft | 1,372 sq ft | 2 | 164 ft | $3,346 |
| 50 × 30 ft | 1,500 sq ft | 1,692 sq ft | 2 | 198 ft | $3,886 |
| 50 × 40 ft | 2,000 sq ft | 2,212 sq ft | 3 | 248 ft | $5,196 |
| 60 × 40 ft | 2,400 sq ft | 2,632 sq ft | 4 | 290 ft | $6,356 |
Each vapor barrier cost calculator row here has a 12 in run-up, six 16 in piers, 6 in laps, 10% extra for cuts, liner at $0.50 per sq ft, tape at $30 per 180 ft roll, edge attachment at $1.50 per ft and labor at $1.50 per sq ft covered.
The 1,500 sq ft space still fits in two rolls, so its liner cost matches the smaller spaces, and only labor, tape and edge attachment grow with its extra 320 sq ft.
Labor rates swing more than material prices in any vapor barrier installation cost calculator result. ThePricer lists labor at $1 to $3 per sq ft, which moves the 1,500 sq ft space between about $3,040 and $6,420 with the same liner and tape.
Local quotes, whether from a vapor barrier cost calculator near me search or a contractor visit, can include debris removal, vent sealing or mold treatment, so compare them line by line. A vapor barrier cost calculator for crawl space work only prices the liner, tape and its install.
IRC Laps, Run-Up and Pier Wraps
An unvented crawl space under the IRC needs a continuous Class I vapor retarder over the exposed earth, with joints lapped 6 in and sealed or taped. Its edges must run at least 6 in up the stem wall and be attached and sealed there, under Section R408.3 of the 2021 IRC Chapter 4.
Vented crawl spaces benefit too, which matters for any vapor barrier cost calculator for crawl space work.
Section R408.2 lets the vent area drop from 1/150 to 1/1,500 of the floor area when the ground is covered with an approved Class I vapor retarder, and 6 mil polyethylene is a Class I material.
| Run-up on 40 × 30 ft walls | Area covered | Rolls | Seam tape | Total at sample prices |
|---|---|---|---|---|
| None, flat ground cover | 1,200 sq ft | 2 | 120 ft | $3,040 |
| 6 in, IRC minimum | 1,286 sq ft | 2 | 158 ft | $3,217 |
| 12 in | 1,372 sq ft | 2 | 164 ft | $3,346 |
| 24 in | 1,544 sq ft | 2 | 176 ft | $3,604 |
Each pier takes a wrap the height of the run-up and long enough to go around the pier plus one lap. A 16 × 16 in pier needs a piece 70 in long, and its vertical seam and top edge add about 6 ft of tape per pier.
In vapor barrier cost calculator terms, the edges to attach and seal run 172 ft on the 40 × 30 ft space, 140 ft along the walls and 32 ft around the piers. At a sample $1.50 per ft for termination bar, fasteners and sealant, that edge adds $258 to the job.
Wider Rolls Cut Seams and Tape
A 20 × 100 ft roll covers the 40 × 30 ft crawl space in one roll with 80 ft of seam tape, against two 10 × 100 ft rolls and 164 ft of tape. Every seam a wider roll removes is tape and labor saved in a vapor barrier cost calculator count.
| Roll size, 40 × 30 ft space | Strips | Rolls | Seam tape | Liner left over |
|---|---|---|---|---|
| 10 × 100 ft | 4 × 42 ft | 2 | 164 ft | 558 sq ft |
| 12 × 100 ft | 3 × 42 ft | 2 | 122 ft | 979 sq ft |
| 16 × 100 ft | 3 × 32 ft | 1 | 102 ft | 189 sq ft |
| 20 × 100 ft | 2 × 42 ft | 1 | 80 ft | 600 sq ft |
| 24 × 100 ft | 2 × 32 ft | 1 | 70 ft | 1,005 sq ft |
| 32 × 100 ft | 1 × 42 ft | 1 | 38 ft | 1,821 sq ft |
The 16 × 100 ft roll is the tightest fit here, with the least liner left over. A 12 × 100 ft roll costs a second roll and leaves almost 1,000 sq ft spare, so roll width matters as much as price per square foot.
Strip direction matters less on this space. Running the 10 ft strips across the 30 ft width instead of along the 40 ft length takes the same 2 rolls and 2 ft more tape, so lay them whichever way is easier to work.
For a vapor barrier cost calculator tape line, vapor barrier tape goes on every lapped seam and every pier wrap seam. Tape sold in 180 ft rolls covers the 40 × 30 ft space in one roll at 10 ft wide, while the 2,000 sq ft space needs two.
Mil Thickness and Material Price
Moving the 40 × 30 ft crawl space from 6 mil to 20 mil liner raises the job from about $3,346 to $5,846 at sample prices. In a vapor barrier cost calculator, thickness changes the liner line only, since the area, laps and tape stay the same.
| Liner, 40 × 30 ft space | Sample price | Liner for 2 rolls | Total with labor | Per sq ft covered |
|---|---|---|---|---|
| 6 mil polyethylene | $0.50 per sq ft | $1,000 | $3,346 | $2.44 |
| 10 or 12 mil liner | $0.95 per sq ft | $1,900 | $4,246 | $3.09 |
| 20 mil liner | $1.75 per sq ft | $3,500 | $5,846 | $4.26 |
Published 20 mil prices disagree widely. ThePricer lists 20 mil material at $1.50 to $2.00 or more per sq ft.
Angi's July 2026 crawl space encapsulation cost guide lists the same liner at $0.50 to $0.70, so price your own roll, such as a vapor barrier cost calculator Home Depot check, before trusting any per square foot figure.
Thicker liner does not stop more vapor once it meets Class I, which is 0.1 perm or less. What it buys is puncture and tear resistance, which matters where people crawl, store things or work on plumbing.
A 6 mil sheet suits a crawl space nobody enters. A 10 to 20 mil reinforced liner suits one with regular service traffic, and it is the usual base for full encapsulation.
Encapsulation Versus a Ground Cover
By vapor barrier cost calculator math, encapsulating the same 40 × 30 ft crawl space with liner up 3-1/2 ft walls covers 1,802 sq ft and takes 3 rolls of 10 × 100 ft, about $4,521 with edge attachment at sample prices, or $5,521 with a $1,000 dehumidifier.
A 20 × 100 ft roll cuts that to 2 rolls and 241 ft of tape, since the 3-1/2 ft wall band and the floor both fit in fewer, wider pieces.
The wall liner laps 6 in onto the floor sheet and seals along the full 140 ft perimeter, and the piers are wrapped full height. That is why encapsulation needs nearly twice the tape of a ground cover, 321 ft against 164 ft.
Full encapsulation also seals vents and usually adds a dehumidifier. Angi puts encapsulation at $5,000 to $15,000, with an average of $5,500, $2,000 to $10,000 for 1,000 sq ft and $4,000 to $20,000 for 2,000 sq ft.
The same guide lists dehumidifiers at $800 to $1,200 and labor at 50 to 70% of an encapsulation job. Crawl space encapsulation cost for 1,000 sq ft lands well above a plain vapor barrier because of that equipment and sealing work.
Under a Concrete Slab
The IRC requires a 6 mil polyethylene or approved vapor retarder under a slab on grade, with joints lapped at least 6 in, in Section R506.2.3 of Chapter 5. It goes between the base course and the concrete.
The concrete industry asks for more. The National Ready Mixed Concrete Association's CIP 29 recommends a minimum of 10 mil, rated 0.1 perm or less under ASTM E1745, with seams lapped 6 in and taped.
AECOM Hunt's November 2025 bulletin on slab vapor retarders goes further, calling for 15 mil Class A material over stone, because 10 mil poly can tear under construction traffic. Over gravel or crushed stone, thickness is about puncture resistance more than vapor.
| Slab | Edge turned up | Area covered | 10 × 100 ft rolls | Seam tape |
|---|---|---|---|---|
| 20 × 20 ft garage | 6 in | 440 sq ft | 1 | 42 ft |
| 24 × 24 ft garage | 6 in | 624 sq ft | 1 | 50 ft |
| 40 × 30 ft slab | 6 in | 1,270 sq ft | 2 | 123 ft |
A vapor barrier cost calculator for concrete slab work should price the sheet before the pour, since there is no way to add it later. Moisture-sensitive floors such as wood, vinyl or epoxy, sized in the Epoxy Calculator or Flooring Calculator, are where the thicker sheet pays off.
Basement Walls and Mobile Homes
In a vapor barrier cost calculator for basement walls, a 140 ft run at 8 ft high needs 1,120 sq ft of vapor retarder. On 10 × 100 ft rolls that is 2 rolls laid lengthwise along the wall, with only 8 ft of tape where the two rolls meet.
Any vapor barrier cost calculator for walls has to follow climate rules, not crawl space rules, since the sheet sits on the warm side of the insulation.
The IRC's Section R702.7 calls for a Class I or II vapor retarder on the interior side of frame walls in Climate Zones 5 through 8 and Marine 4, so check your zone before buying sheet for basement walls.
The wall area itself comes from the Wall Square Footage Calculator, and the drywall that covers the barrier from the Drywall Calculator.
A 14 × 70 ft single-wide mobile home needs a 980 sq ft ground cover in a vapor barrier cost calculator count. Two 10 × 100 ft strips leave a 70 ft seam to tape, while one 20 × 100 ft roll covers it with no seam at all.
A 16 × 76 ft home covers 1,216 sq ft and also fits on one 20 ft wide roll. Replacing the vapor barrier under a mobile home is mostly removal and crawling labor, so the seam-free roll saves the hardest part of the job.
Straight Answers on Vapor Barrier Cost and Thickness
Every vapor barrier cost calculator answer below uses the 40 × 30 ft crawl space, 6 in laps and sample prices of $0.50 per sq ft for 6 mil liner and $1.50 per sq ft for labor unless the question names something else.
What is the cost of a vapor barrier?
A basic crawl space vapor barrier costs $1.35 to $2.00 per sq ft installed, citing HomeAdvisor through ThePricer, or about $1,350 to $2,000 for 1,000 sq ft. Full encapsulation runs $5,000 to $15,000 in Angi's 2026 figures.
How do I calculate how much vapor barrier I need?
Add the floor area, the perimeter times the run-up height and each pier's perimeter times its wrap height.
Then add 6 in for every seam and about 10% for cuts, the same steps behind any vapor barrier cost calculator. The 40 × 30 ft space comes to 1,372 sq ft covered and 2 rolls of 10 × 100 ft.
How much to charge to install a vapor barrier?
Installers commonly charge $1 to $3 per sq ft for labor, according to ThePricer. On the 1,372 sq ft covered in a 40 × 30 ft crawl space, that is $1,372 to $4,116 before liner and tape, with tight access and debris removal at the high end.
Which vapour barrier is best?
Under a slab, a 10 to 15 mil sheet meeting ASTM E1745 at 0.1 perm or less is the best match, per NRMCA and AECOM. In a crawl space, any Class I liner meets the IRC, and a reinforced 10 to 20 mil liner lasts best where people move around.
How much is a 20 mil vapor barrier?
A 20 mil liner costs $0.50 to $0.70 per sq ft in Angi's figures and $1.50 to $2.00 in ThePricer's. The 2,000 sq ft of liner a 40 × 30 ft crawl space needs runs $1,000 to $4,000 for material alone across those ranges.
What is a good vapor barrier thickness?
A 6 mil sheet meets the IRC for crawl space ground covers and slabs, while 10 mil is the NRMCA minimum under slabs. For crawl spaces with foot traffic, a 12 to 20 mil liner resists punctures from knees and tools that would tear 6 mil.
Is a vapor barrier necessary?
The IRC requires one under slabs on grade and over the ground in unvented crawl spaces. In a vented crawl space it is optional, but covering the ground lets the code vent area drop from 1/150 to 1/1,500 of the floor area.
What is the minimum thickness of a vapour barrier?
The minimum under a residential slab is 6 mil polyethylene under IRC Section R506.2.3. For crawl spaces the IRC sets a Class I rating rather than a thickness, which 6 mil polyethylene meets.
Can I install my own vapor barrier?
A DIY install is common for a ground cover, and it removes the largest vapor barrier cost calculator line.
On the 40 × 30 ft crawl space, doing it yourself drops the job from $3,346 to $1,288 for liner, tape and edge attachment, but the edges still need to be attached and sealed to the stem wall.
How long will a vapor barrier last?
A vapor barrier lasts about 10 to 20 years in ThePricer's estimate, with 6 mil sheets near the short end and 20 mil liners often carrying 20-year warranties. Foot traffic, sharp stones and pests shorten that, so inspect it whenever you go into the crawl space.
When to install a vapour barrier?
Under a slab, it goes on the base course before the concrete is poured. In a crawl space, it goes in after debris is cleared and any water problems are fixed, and on framed walls it goes up after insulation and before drywall.