How to Caulk Windows

The caulk around windows keeps drafts out and prevents moisture from seeping in, which can damage the windows, paint and trim. Over time, moisture can even seep into the walls, resulting in costly repairs. Weather will cause caulk to shrink and expand and eventually crack and become brittle. Checking for damaged caulk and making the repairs will save you money in the long run.

  • Putty knife
  • Razor knife
  • Caulk gun
Scrape away any old caulk or debris with the putty knife. You may need to use the razor knife for more persistent areas. Clear all the caulk off, whether it looks damaged or not.

Cut the tip of the caulk tube, with a razor knife, on about a 30-degree angle. The size of the tip opening should be about 1/4 inch. Puncture the seal in the caulk tube. Most caulk guns have a wire attachment for this purpose, but you can also use a nail or screwdriver. Load the caulk tube into the caulk gun.

Apply the caulk to the joint area of the window. Keep continuous pressure on the trigger of the caulk gun so the caulk flows evenly. Move the caulk gun at a steady pace so that the caulk is filling the joint completely. When stopping a bead of caulk, hit the release on the caulk gun to relieve pressure on the tube.

Caulk all sides of the window. Wet your finger slightly and smooth out the caulk with it. Also use a spoon for smoothing the caulk bead.

Clean the tip of the caulk tube and your hands before moving on to another window.

Tips and Warnings

  • Choose the correct caulk for the application. A latex caulk is fine for interior jobs, but use caulk rated for outdoors for exterior jobs.

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