How to Seal Around Basement Windows

Basement windows, like other windows and openings in your house, are susceptible to air leaks, small cracks and other openings.

Over time, the caulking around the windows can deteriorate and let in air, water and insects. Failure to seal around your basement windows can lead to a not only a cold basement, but also an increase in energy costs. To seal around basement windows, you need a tube of masonry caulk and a caulking gun.

Use a ladder to remove any curtains or drapes from the basement windows. Set them aside.

Wearing work gloves to protect your hands, scrape away any old caulking from the basement windows with a putty knife or large screwdriver.

Wipe the window frame with a rag or shop towel to remove any dirt, dust and old caulking. Scrape any caked-on dirt around the window with the putty knife or large screwdriver.

Pull back the push rod on a caulking gun and load the tube of masonry caulk into the caulking gun's chamber.

Push the push rod into the tube of masonry caulk until it stops.

Use a utility knife to cut the tip of the tube of masonry caulk at a 30-degree angle.

Start at the top of the window frame and apply the caulk by squeezing the caulk gun's trigger. Hold the caulking gun at a 90-degree angle to the window frame and move slowly down the frame with one straight, continuous stream of caulking. Try not to stop or pause.

Release the caulk gun's trigger before pulling the gun away from the window frame.

Use the putty knife to smooth any caulking that didn't adhere to the window frame.

Repeat Steps 7 through 9 for the other sides of the window pane.

Let the caulking dry for 15 minutes and reapply caulking to any large cracks or openings.

If you see any light or feel any air coming from around the basement window frame, apply caulking to the area where you see the light or feel the air.

Fill any large holes with a can of expanding foam. Shake the can for one minute, take off the cap and spray the foam into the hole.

Rehang any curtains or drapes you removed from the basement windows.

Things You Will Need

  • Ladder
  • Putty knife or large screwdriver
  • Work gloves
  • 2 rags or shop towels
  • Caulking gun
  • Masonry caulk
  • Utility knife
  • Expanding foam


  • Let the caulking or expanding foam sit overnight, then check the basement windows for air and light coming in around the window frame. Reapply caulking or expanding foam if you discover any light or air coming in around the windows.

About the Author

Nick Davis is a freelance writer specializing in technical, travel and entertainment articles. He holds a bachelor's degree in journalism from the University of Memphis and an associate degree in computer information systems from the State Technical Institute at Memphis. His work has appeared in "Elite Memphis" and "The Daily Helmsman" in Memphis, Tenn. He is currently living in Albuquerque, N.M.