Filling Holes and Cracks with Insulating Foam Sealant

Air leakage through lots of small holes and cracks around the home is a major cause of heating and cooling loss. In fact, adding up all the holes in the average residence is similar to heating and cooling your house year-round with an open window. To reduce energy costs, air-seal and eliminate drafts, start with an easy fix by applying insulating foam sealant throughout your home. According to the U.S. Environmental Protection Agency, using foam sealant to fill these gaps can typically save up to 20 percent annually on heating and cooling costs.


  • Gloves (optional)
  • Eye protection
  • Straight edge or butter knife
  • Insulating foam sealant

Insulating foam sealants come in different applications (i.e. windows and doors, gaps and cracks, firelock, aquascape and landscape). Be sure to apply the appropriate foam sealant and read all instructions thoroughly before applying. For this application, we will apply a gaps and cracks sealant.

  1. Before you apply the foam, make sure the area is free of dust, dirt and oil.
  2. Apply sealant foam on the outer part of the hole.
  3. Only fill about a quarter of the hole to allow room for the foam to expand.
  4. Use a flat edge tool or butter knife to scrape off excess foam.

Note: Read instructions to determine drying time of the foam; it may take several hours to dry completely. The cost for a 12-ounce can should be less than $5 at your local hardware or home improvement store.

Foam sealants expand to form an outer skin containing closed air cells that provide an effective barrier against energy loss. And when dry, most of these sealants can be painted to match trim. Use around windows and doors, plumbing fixtures, electrical outlets, baseboards, sill plates, exhaust vents, siding edges, sky lights, attic fans, garage ceilings, etc. This simple “recipe” can help you conserve energy and reduce heating and cooling bills.