Interior and Exterior Window Caulking

Caulk near a window.

To weatherize your windows and make your moldings more attractive, consider adding window caulking. This is a cost-effective method to weatherize interior and exterior windows and is easy to do on your own. If done properly, interior and exterior caulking can help save on your energy bills for many years.

Interior Window Caulking

Latex caulk is a type often used for interior applications, like windows. This type of caulk is has a shorter life than other caulks, but it can be extended through proper application. You can apply it to windows inside the home in cracks up to ¼-inch wide. It does not withstand extreme temperatures, so should only be used for the interior, not the exterior. The caulk adheres well to wood and paint if the surface is clean, but can also be used on other materials.

Exterior Window Caulking

Exterior window caulking requires caulk that can adhere to a variety of surfaces and withstand temperature changes. Butyl rubber caulk can be used in cracks that are as large as ¼-inch wide. Depending on the age and installation of your windows, they may have large gaps to be filled and will require a caulk like butyl. Butyl caulk is available in different colors and can be tinted to match the color of your home if you do not intend to paint.

Caulk for Both

Acrylic latex silicone blend caulk provides the indoor and outdoor benefits of both acrylic latex and butyl. This blend is an all-purpose caulk that can withstand temperature changes and is resistant to water. It is available tinted or can be painted over. It adheres best to wood, but can be used on nearly any surface, including aluminum siding, drywall, brick, and even glass. Like water-based caulks, acrylic latex silicone blends can be wiped with water to remove excess.

Window Caulking Tips

The most important step in applying caulk is the surface preparation. For the caulk to adhere properly, the surface must be completely clean and free of dust and paint or wood chips. Windows that need caulking often have chipped paint. The windows are also prone to dust build up. Clean the window area with soap and water and let it dry. Use a wire brush to clean the crack before applying caulk. Next you should re-wash the area to make sure everything is removed. If you plan to repaint the entire window frame, complete the preparation work to the whole frame before caulking.

Caulk can be applied with a caulking gun or straight from the tube. For thin gaps, the tube method is fine. Make sure to cut the end of the tube so a thin bead comes out. For larger gaps, as expected on exterior window applications, a gun should be used. If you are filling a larger gap, cut the tip of the caulk tube accordingly. The gun will allow you to make a thick steady bead. Make sure to keep a damp cloth with you when caulking windows so you can wipe the excess off the wall.