How To Insulate Your Home’s Rim Joists

Insulating the rim joists of your home is a simple and effective way to lower your energy costs, improve comfort, and reduce drafts. Rim joists are the wooden framing members that run along the perimeter of your house and provide support for the floor joists. Insulating them can prevent air leaks and help keep your home’s temperature regulated year-round.

Here’s how to insulate your home’s rim joists safely and easily.

Step 1: Gather the Required Tools and Materials

Before you begin insulating your rim joists, make sure you have all the necessary tools and materials on hand. Here’s what you’ll need:

  • Insulation (either fiberglass batts or rigid foam board)
  • Caulk
  • Tape measure
  • Utility knife or saw
  • Safety goggles
  • Work gloves
  • Dust mask
  • Foam insulation board adhesive (optional)

Step 2: Measure the Rim Joist Area

Using a tape measure, measure the perimeter of your home’s rim joists to determine how much insulation you will need. It’s important to accurately measure the area to avoid wasting materials and ensure proper insulation coverage.

Step 3: Prepare the Rim Joist Area

Start by removing any existing insulation or debris from the rim joist area. Use a utility knife or saw to trim any protruding nails or screws. Clean the area with a broom or vacuum to ensure it’s free of dust and debris.

Step 4: Install the Insulation

Cut the insulation to fit the length of the rim joist sections. Carefully push the insulation up against the rim joist area. Depending on the type of insulation you choose, there are different installation methods:

Fiberglass batts

If you’re using fiberglass batts, simply press them into place between the floor joists and against the rim joist. If the insulation doesn’t fit snugly, use a utility knife to trim it to the appropriate size.

Rigid foam board

If you’re using rigid foam board, use a saw or utility knife to make cuts in the insulation. Then, place the foam board against the rim joist and secure it with foam insulation board adhesive.

Step 5: Seal the Air Leaks

To prevent air leaks and drafts, use caulk to seal any gaps or cracks between the insulation and the rim joist. Caulk around electrical and plumbing penetrations to further reduce air infiltration.


Insulating your home’s rim joists is an important step in improving energy efficiency and keeping your home comfortable year-round. With the right tools and materials, you can easily install insulation and reduce air leaks in your home. Follow these steps to insulate your rim joists and enjoy the benefits of lower energy bills and a more comfortable home.

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