The do it yourself resource for homeowners from home improvement professionals.

How to Install Retrofit Windows

The good thing about retrofit windows is that they’re usually designed to fit right into your old window frame. This means you don’t have to go through the trouble of removing the frame and installing a new one. Instead, you can just replace the window. Here, our window experts share how to install retrofit windows:

What you’ll need to install retrofit windows:

  • Retrofit windows (sized to your frame opening)retrofit windows
  • Protective gloves
  • Putty knife
  • Warm water
  • Mild soap
  • Rag or sponge
  • Level
  • Wooden shims
  • Hammer or mallet
  • Screws, screwdriver
  • Window caulk
  • Foam insulation
  • Wood trim
  1. First, put on your gloves to protect from broken glass.
  2. Next, remove the panes from your window.
  3. Use a putty knife to remove any dried caulk around the window frame.
  4. After that, use warm water, mild soap, and a rag or sponge to clean the window frame area.
  5. Let the area dry completely.
  6. Next, place your retrofit window inside of the frame opening.
  7. Check to make sure that the window fits correctly.
  8. If it does, use your level to make sure the window sits level. If it’s not, you’ll need to use a hammer (or mallet) and wooden shims to adjust it.
  9. Once the window is in place and level, screw it into place with your screws and screwdriver.
  10. Place some window caulk over the screw heads to ensure they form a seal.
  11. Next, locate your retrofit window from outside of your home.
  12. Run a bead of window caulk around the frame where the frame meets the siding.
  13. After that, return to your window on the inside of your home.
  14. Use your foam insulation to fill in the gaps around your window frame and seal it.
  15. Finish your retrofit windows by installing wood trim over top of the insulation. Make sure you paint or stain the wood trim to your liking before you install it.

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P.J. Fitzpatrick, Inc.

21 Industrial Blvd
New Castle, DE 19720

  • NJ Lic. #13VH10727200
  • DE Lic. #2009603070
  • PA Lic. #PA011323
  • MD Lic. #105494

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