How to Insulate Window Frames

Framing a wall for a window includes making a header, sill and two sides to accommodate the window. Small cracks between the boards installed next to each other can leak air. There are also tiny air leaks between the window and the framework that need filling with insulation. Properly sealing these areas with a can of spray foam insulation will save you money on heating and cooling bills.

Insulating window frames keeps drafts out of a home.
  1. Wearing rubber gloves and safety goggles, insert the applicator in the nozzle of the foam insulation. Insert the applicator tip into the crack around the window frame where the metal frame meets the wood on the inside of the home. Press the nozzle to spray the insulation into the crack, starting at one corner and working across or down while moving the can. Fill the crack about one-half full of insulation.
  2. Repeat this process on all sides of the window frame.
  3. Let the foam insulation dry for about 10 minutes. Place a metal putty knife at a 45-degree angle to the exterior surface. Push the knife forward and back to cut off any excess insulation so it is flush with the window surface.
  4. Insulate the exterior of the window in the same manner.

Things You Will Need

  • Rubber gloves
  • Safety goggles
  • Foam insulation
  • Metal putty knife


  • Foam insulation doubles in size as it dries. Filling the cracks between the window and frame halfway allows the foam to expand and insulate the entire area.


  • Foam insulation may permanently stain clothing. Wear old clothes or work clothes when using this product.

About the Author

Mary Lougee has been writing for over 10 years. She holds a Bachelor's Degree with a major in Management and a double minor in accounting and computer science. She loves writing about careers for busy families as well as family oriented planning, meals and activities for all ages.

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