How to Install Attic Insulation for Cold Climates

An extreme close-up of a pink wedge of fiberglass insulation.
  • 4-12 hours
  • Beginner
  • 500-900
What You'll Need
Fiberglass roll insulation
Utility knife
Staple gun
Safety glasses
Dust mask

If you’re going to keep your house warm and cut your energy bills, you’ll need to know how to install attic insulation. Much of the heat from your house is lost through the attic, and good attic insulation will keep that heat in the living areas of your home.

Step 1 - R-Value

Insulation is measured by the R-value. The higher the R-value, the more effective the insulation will be. Find the fiberglass roll insulation with the best R-value for your particular climate and attic.

Step 2 - Measuring

If your roof beams are less than 16 inches wide, you’ll need to cut your insulation to make it fit because the rolls are usually 16 inches wide.

Measure the distance from the floor of your attic up to the peak of the roof and multiply that by the number of gaps between the beams. This will tell you how many feet of roll insulation you need for the roof.

Next, measure the width of the attic and multiply that by the number of openings between the joists. This will tell you how many feet of roll insulation you need for the attic floor.

Step 3 - Installing Insulation

Before you handle and work with insulation, put on gloves, a dust mask, and safety glasses.

Cut the rolls to length with a utility knife. Holding one end of the piece of insulation so that the backing paper is facing you, climb up the stepladder so you can reach to the ridge line. You’ll see that there are tabs on the paper. You will need to pull these out and use them for attaching the insulation to the beams.

Staple the tabs to the beams. The staples should be spaced about 6-8 inches apart to give the best support. Repeat this for all the spaces between the beams.

Step 4 - Floor Insulation

Don’t stop with the roof. You’ll keep the house a lot warmer by installing insulation between the joists. This will also allow you to add a plywood floor to the attic.

Simply roll out a roll of insulation to the desired length and cut with a utility life for each space between the joists. Repeat until you’ve covered the entire attic.

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