DIY Projects

Project File #10
Do It Yourself
As Soon As Possible
Reduce overall heating and cooling costs

Air sealing and insulating your floor saves you energy on heating and cooling, and improves air quality.

Improper sealing in your home’s flooring, basements, and crawlspaces can lead to air leakage. This, in turn, means you’re spending more money trying to keep your home comfortable. By air sealing these problem areas and adding insulation, you can make a big impact on your energy use.

Project Overview

Tools and Materials:

  • Utility knife
  • Table or circular saw
  • Caulk gun
  • Measuring tape
  • Lights
  • Straight edge or markers
  • Foam/caulk/construction adhesive/duct mastic
  • Insulation—cavity batts or rigid foam board insulation
  • Sheathing—OSB/plywood or code-approved foam board
  • Fasteners—screws with washers or button-capped nails


  • Dust mask/respirator
  • Gloves
  • Safety glasses
  • Kneepads
  1. Knowing where to air seal and insulate below the floor can be a complicated decision. Do you air seal and insulate the floor above your head, or the walls of the foundation? If you chose to seal and insulate the floor, this project will help guide you.
  2. Air sealing must be done before insulation is installed. The floor often has more holes, gaps, cracks, and ductwork that need to be air sealed before insulating. The floor itself can also be much leakier depending on the subfloor material and how many seams are there.

Download Project File

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