How to Seal a Window

How to Seal a Window

Before You Start

The first thing you should do is walk around your house and find which windows need to be sealed. There are several ways you can do this:

  • If it’s a rainy day, check for signs of moisture along the window frame.
  • If it’s a windy day, moisten the tips of your fingers, run them along the window frame, and see if you can feel the air coming through.
  • If it’s a sunny day, look at those same areas around the edges of the window frame and check to see if there’s any daylight coming through.
  • Or take an incense stick, light it, then hold it at various places around the frame, and see if the smoke moves – which indicates a draft

Here’s how to do it:

  1. Use a pry bar and a hammer to remove the window trim (either inside or outside — not both).
  2. Fill the void with expanding spray foam in a can.Don’t worry about overfilling. Let it bulge out of the wall. What you don’t want to do is touch the foam while it’s wet; you’ll make a huge, hard-to-clean-up mess.
  3. After the foam dries (it’ll take several hours), use a knife to cut off the excess.
  4. Replace the trim in the reverse order in which you removed it and touch up paint as necessary.

Leaks also occur when weatherstripping wears out. You may have to remove the operable portion of the window to find the weatherstripping:

  • For sliding windows, open them halfway and lift the window out of the bottom track. Then pull the window out of the opening bottom first.
  • For single-hung windows, usually you just release a lever on the side track(s) of the window frame. Contact the manufacturer for specific instructions.

After you remove the operable portion of the window, it becomes pretty obvious where the weatherstripping is and how it has to be replaced. Most home centers offer replacement weatherstripping in peel-and-stick rolls. If you aren’t sure about what to do, take the section that you removed to the store with you or photograph the area that needs attention.

You may need an adhesive solvent to unstick old weatherstripping. Adhesive solvent is available in spray cans for easy application.

If you have metal or vinyl frame windows, check the drain holes at the outside edge of the bottom portion of the window frame. During rains, water can fill the bottom track, leak to the inside of the home, and flood the area surrounding the window. Drain or weep holes allow water to escape from the frame, preventing flooding. Use a piece of wire or a small screwdriver to ensure that the holes are clear.