Should the Gaps of Drop Siding Be Filled With Caulk Around Window Frames?

Benefits

• Using caulk to seal the openings between drop siding and window frames prevents air from entering the home. Although the design of drop siding means the gaps are very small, there is still an opening for the air to enter the home. Caulk should be used anywhere two different types of materials or parts of the house meet, regardless of how small the gaps seem. Take special care to caulk the corners between the window frame and siding, as the gaps around corners and angles are often larger than in straight runs.

Selection

• There are many different types of caulk available, and they have specific uses. Silicone, latex and acrylic latex are primarily used for interior uses. Oil or resin based caulk and urethane and polyurethane caulk are recommended for outdoor use. Oil and resin caulks are inexpensive but last only a few years before needing replaced. Urethane and polyurethane caulks are more expensive and last much longer, often over 20 years. Urethane and polyurethane caulks also shrink very little as they cure, and adhere to a wide range of products, including brick, stone and vinyl, making them a good choice for caulking between drop siding and window frames.

Application

• It is important to caulk around the windows in dry weather, when the air temperature is between 50 and 70 degrees. If the gaps have been caulked previously, use a stiff bristled brush or screwdriver to scrape the old caulk out of the gap. Before you begin, make sure that both surfaces are dry and clean. Apply the caulk, using a caulking gun, with a steady, even pressure. Use the tip of the gun to press the caulk deep into the gap, rather than keeping it on the surface of the house.

Considerations

• If the gap between the drop siding and the window frame is wider than 3/8 inch, use rope caulk or sponge rubber as a filler. Traditional caulk is made for narrower gaps, and trying to seal a wide gap with this type of caulk will not work. The caulk can fall into or out of the gap, or, if you are able to close off the gap, it will be applied so thick that it cannot cure properly.