Where Not To Caulk Around Windows

Installing new windows is a great way to give your home a facelift and lower your energy bills. If you’re planning to replace just a few windows or want to do some maintenance on the ones you have, the window experts at Mr. Handyman® have some helpful window caulking advice.

Proper window installation requires sizing, setting, and caulking to promote good airflow in your home. Accidentally sealing the wrong parts of your windows could lead to costly damage. This guide will show you where not to caulk around windows to save time and money in the long run.

Should You Caulk Around Windows?

Did you know that heat loss through windows is responsible for 25% to 35% of energy use? Caulking around windows can prepare your home for the winter and summer months, which will stop air leaks and prevent heating or cooling loss.

As long as you don't caulk where you shouldn't, you’ll spend less on energy and keep you or your family comfortable throughout the year.

If you're performing maintenance on existing windows by replacing the old caulk, these tips will help make the project more efficient. You'll learn where not to caulk and how to create a weather-tight seal for your old windows that will help reduce heating and cooling loss.

Don’t get caulk in weep holes

Before installing windows and applying caulk, check to see if your windows have weep holes. While the majority do—wood, vinyl, and metal window frames included—some manufacturers sell styles that don’t. These windows usually have a sloped lower sill that redirects water away from the windows.

Caulking over weep holes will cause a big problem because it will stop them from doing their job: preventing rot, mold, or rust from developing. Weep holes allow moisture behind the window to exit the frame. If you caulk over them, the moisture has nowhere to go. So, if you want to avoid costly repairs down the road, keep caulk away from window weep holes at all times.

Don’t caulk around window trim

Many modern homes have trimmed-out windows that sit above the siding. As a rule of thumb, you should never caulk this type of window. There is no reason to seal the joints because it provides no benefit. In fact, if you do, you may end up causing more harm than good. The trimming already redirects excess moisture away from the windows; adding caulk could lead to moisture getting trapped inside, leading to damage you may not discover until it’s too late.

Don’t apply caulk on moveable parts

While it may be tempting to caulk all around your windows, caulking movable parts, for instance, may cause your window to seal shut or impede its operation. The ledge above the window frame also doesn’t need any caulk. This area has a drip edge that helps keep the frame dry. Leave the top of your window caulk-free if you are replacing siding or framing.

Don’t caulk over old caulk

Unfortunately, there are no shortcuts or workarounds for this tip. You only need elbow grease, patience, and a few tools to caulk effectively. Tackle loose window caulk first by prying up a corner with your putty knife. Once you get a grip, use your needle-nose pliers to peel away as much old caulk as possible.

If the caulk removal becomes more challenging, try a razor knife or sharp scraper, but be careful. Always direct the blade away from you and keep your free hand out of harm's way. Wearing eye protection is also recommended. The work is tedious, but the extra effort will save you money and time down the road.

Once you've removed as much caulk as possible with your putty knife and blade, scrub away the remnants with a stiff brush. You may need to use 90% rubbing alcohol to remove any remaining residue, so be cautious not to get it on other surfaces.

Caulking Tips From the Pros

Now that you know where not to caulk around windows, how about some pro tips for where you should apply caulk? Let's review some of our field-tested tips for caulking windows.

Caulk the inside and outside of Windows

When dealing with older windows, professional window installers and repair experts know it’s best to apply caulk to the interior and exterior of windows. Windows require a seal on both sides to avoid air leaks and moisture problems. A caulk gun will ensure you fill gaps and get a clean line.

Use the correct caulk for the job

Walking down the caulk aisle of a home improvement store can feel overwhelming, especially when you don’t know which product to buy. There are many types of caulk for windows, and each works best in a particular environment and based on specific usage. You’ll find exterior window caulk as well as sealant for the interior of windows, humid spaces, masonry siding, and other unique applications.

Caulk for the exterior side of windows must be durable and hold up to extreme weather changes. Interior-side windows need a caulk that doesn’t release harmful fumes. If you have a humid room, pick a mold-resistant and waterproof caulk. Masonry siding, often found in basements, requires a caulk compatible with both the window and masonry surface. If you have more questions, check with a local Mr. Handyman for advice.

Know when to caulk for the best results

The type of caulk used and the outside and inside environment have a lot to do with a successful caulking job. Energy.gov recommends caulking windows during dry weather when the temperature is above 45°F.

It's also best to caulk when there is low humidity to prevent the caulk from separating and cracking due to swelling. Typically, the warmer the weather, the faster the caulk will dry and adhere properly, provided the humidity outside is not too high (above 80%).

Depending on humidity levels and ventilation, silicone and acrylic latex caulk on interior windows can dry within 30 minutes. While the outside temperature isn't as critical for indoor caulking, be aware that condensation on the inside of your windows may need to be remedied before you begin caulking.

If possible, caulk the window's interior when it's warm enough to open it and provide adequate ventilation.

Hire a Professional Window Expert

Installing new windows requires a lot of skill and knowledge, and caulking existing ones takes time and patience. One wrong move, and you may end up with broken glass, a damaged frame, or more work than you bargained for. Hiring a professional will save you time and prevent headaches.

Whether you need window installation, repair, or maintenance, trust your home to the local service professionals at Mr. Handyman. We offer a range of home maintenance services that help homeowners get things done. Each of our service professionals has an average of 10 years of experience, and we back every job with our Neighborly Done Right Promise^™.

Give your windows the treatment they deserve. Contact us online or call your local Mr. Handyman today!

This article is intended for general informational purposes only and may not be applicable to every situation. You are responsible for determining the proper course of action for your home and property. Mr. Handyman is not responsible for any damages that occur as a result of this blog content or your actions. For the most accurate guidance, contact your local Mr. Handyman location for a comprehensive, on-site assessment.