Crawlspace Insulation Calculator
There are two ways to insulate a crawlspace: at the floor above it, or around the perimeter walls with the space sealed up. This sizes both so you can compare material and price before you commit.
Your project
Covers cuts, compression and odd bays. 10% is the usual default.
Your results
- Perimeter wall area
- 449 sq ft
- Subfloor area
- 1,232 sq ft
- Vapor barrier needed
- 1,288 sq ft
- R-value at this thickness
- R-10
- Wall material cost
- $377
- Floor material cost
- $1,035
- Installed cost (walls, pro)
- $867
Encapsulated approach
Insulating between the joists instead
Ground cover plus 15% for overlap
Estimates use typical US material and labor pricing. Confirm quantities against the coverage chart on the bag before you buy.
Gear for this job
Rigid Foam Board Insulation
Multi Purpose XPS Foam Board,2 Pack 15.6x11.7X 2in Polystyrene Craft Foam Sheets,Rigid and Easy to Shape,DIY Modeling Art Projects, Party Decoration, Cosplay Prop Production, Carve,Heat Insulation
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Double-Layer Insulated Foam Panels, 3-Pack Insulation Seal Panels for Portable AC Window Vent Seal Kit, Thick Adjustable Insulation Board, Air Conditioner Window Gap Filler
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GCGOODS Window Air Conditioner Insulated Foam Panels, Winter Surround Insulation Side Panel with Top Seal Strip for Window AC Unit Indoor, White
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Vapor Barrier Plastic Sheeting
Plastic Sheeting (10' x 25') Long, 6 Mil - UV Protection Poly Sheeting Polyethylene Film, Heavy Duty Greenhouse Plastic Sheeting
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Frost King P1025/6W Polyethylene Sheeting, 10' x 25' x 6 mil., Clear
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Aluf Plastics 6 MIL Thick Extra Strong Heavy Duty Clear All Purpose Vapor and Moisture Barrier Sheet Tarp/Drop Cloth - 10' x 25' - for Painting, Furniture, Carpet, Contractor, & Construction
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Foil Tape Hvac Insulation
Romeda Aluminum Foil Tape, 2 inch x 65 Feet Foil Tape (3.9 mil), Silver Insulation Adhesive Metal Tape, High Temperature Heavy Duty HVAC Tapes for Ductwork, Dryer Vent, HVAC
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Aluminum Foil Duct Tape Heavy Duty Waterproof, Premium Silver Metal HVAC Heat Tapes (2"*65Feet,3.9mil), High Temperature, Dryer Vent Insulation Tape for Ductwork, Ducting, Sealing, Patching, Furnace
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ETERART Aluminum Foil Duct Tape, High-Temp Seal for HVAC,2" x 20Yds | Heavy-Duty, Dryer Vents & Insulation, Stops Air Leaks & Resists Extreme Heat for Home Repair, Silver, easy to apply, durable
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How this calculator works
- Wall area = 2 × (length + width) × wall height
- Subfloor area = length × width
- Vapor barrier = floor area × 1.15 for overlap
- Cost = area × cost per sq ft-inch × thickness
Frequently asked questions
Should I insulate crawlspace walls or the floor above?
If the crawlspace is dry and can be sealed, insulating the perimeter walls and encapsulating with a vapor barrier performs better — ducts and pipes end up inside the conditioned envelope. Insulate the floor above only if the crawlspace stays vented.
Do I need a vapor barrier in a crawlspace?
Yes. Bare dirt pushes gallons of moisture into the house every day. Use 6 to 20 mil sheeting across the whole floor, lapped 12 inches and run up the walls.
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Perimeter wall area
449 sq ft