Crawl Space Insulation Cost Calculator
Estimate crawl-space wall insulation from the wall area times the price per square foot from your quote — rigid board or spray foam, at the R-value you are targeting.
Calculator
Insulating 390 sq ft of crawl-space wall at $2.50/sq ft is about $975.00. Board vs spray foam and the R-value you need change the $/sq ft — enter the figure from your quote.
Formula
Crawl-space wall insulation is priced on the wall area you cover, at a price per square foot you enter for your chosen material:
wall_area = perimeter × wall_height total = wall_area × price_per_sq_ft
Modern practice for a sealed crawl space usually insulates the stem walls rather than the floor above; enter the $/sq ft for the board or spray foam and R-value your project calls for — the tool holds no price list.
Worked example
A 390 sq ft wall area (say 130 ft of perimeter, 3 ft high) at $2.50/sq ft:
- Total = 390 × $2.50 = $975
Spray foam usually costs more per square foot than rigid board but seals and insulates in one pass — enter the figure for the method you are quoting.
Background & practice
In an encapsulated crawl space, insulation typically goes on the stem walls (and the rim joist) so the space stays inside the home’s thermal and air envelope, rather than under the subfloor. Rigid foam board and closed-cell spray foam are the common choices; spray foam is pricier per square foot but air-seals as it insulates, while board is cheaper but needs careful sealing at the seams. The R-value you target — driven by your climate and code — changes the thickness and therefore the price.
Because the material, R-value and access all move the number, the tool asks for your $/sq ft rather than guessing. Confirm code requirements and any fire-rating or ignition-barrier rules with your local building department. Pair wall insulation with encapsulation and a dehumidifier for a complete sealed crawl space.