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Install Crawl Space or Basement Insulation

Install Crawl Space Insulation

Have you ever walked barefoot across a tile or vinyl floor and noticed that it seemed very cold? If so, it may be time to insulate the crawl space or your basement. Insulating the crawl space or basement increases the comfort level in your home and decreases heating and cooling expenses.


Insulate Your Crawspace

R-Value Chart

Step 1

Determine the R-value required in your area by using the chart below or contacting your local contractor or building inspector.

 Zone Roofs Walls Floors
 1 R49 R28 R25
 2 R49 R22 R25
 3 R49 R18 R25
 4 R49 R18 R25
 5 R49 R18 R25
 6 R49 R18 R25

Step 2

Measure the distance between floor joists to determine whether you need 15-inch or 23-inch-wide insulation.


Step 3

Use our insulation calculator to determine how many square feet of insulation you need.


Step 4

Determine how many insulation supports you need. Divide the square footage of insulation required by 4 for 15-inch-wide insulation and by 5 for 23-inch-wide insulation.


Step 5

Spread the polyethylene over the entire crawl space or basement floor. Overlap any seams by 16" to 24" and secure with duct tape. The polyethylene acts as a vapor barrier to prevent excess ground moisture from permeating the insulation.


Step 6

Start at one edge of the crawl space or basement, and install insulation between the joists with the vapor barrier up. The insulation should fit snugly between the joists. If you need to cut the insulation, turn the faced side up, compress the insulation with a straight edge, and cut along the edge with a utility knife. Install wire insulation supports every 24 to 36 inches to hold the insulation in place.


Step 7

Continue installing the insulation until the entire ceiling is covered.


Step 8

Stuff small pieces of insulation into areas around obstructions. Use a broom handle to stuff the insulation into hard-to-reach places.