Where Do I Need to Caulk Windows?

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When it comes to caulking, the more you seal, the better, right? After all, closing off gaps prevents prying winds and rain from entering your home, keeping you snug and dry. While that’s true in theory, it’s not necessary to plug every joint on your window frames—particularly between the glass panes on a replacement window.

It comes down to an issue of design—the type of window and siding material, as well as whether the frame is new or replacing a previous window. Furthermore, there’s an aesthetic benefit to caulking the interior glass—a pretty compelling argument for many homeowners.

Of course, keep in mind that there are plenty of spots you’ll want to avoid caulking altogether, depending on the type of window frame you have and how it fits against your siding. Here are the ins and outs of caulking for your windows.

Sealing Window Leaks

Caulking Window Interiors for Aesthetics

On many windows, caulking between glass panes is something done merely for aesthetic purposes—many homeowners like the antique appearance of fully caulked glass. The caulk between the glass and the frame gives them the finished look that we’re used to seeing, but it doesn’t do much of anything to prevent drafts or keep out the wind and the rain.

However, most windows fit tightly together, so moisture and air leaks between the glass isn’t necessarily a problem. To give them a pleasant appearance, use acrylic latex painter’s caulk—or, if you feel like it, leave them uncaulked.

Special Concerns for Replacement Windows

Replacement windows are typically well-sealed in the interior, so caulking there is often optional. Where you do need to pay attention to sealant is around the frame, where the window fits into the wall opening. Although windows typically come in standard sizes, since the opening was cut to another model, sealing those gaps with expanding foam is vital to your home’s comfort and energy consumption.

When Should I Caulk Between the Frame and Window Panes?

The question of where and how to caulk depends a lot on the kind of siding and frames you choose to install. Some frames, like vinyl, tend to hold the glass more tightly than say, wood frames do. Therefore, if you have vinyl frames going into a home with vinyl siding, you may only need a little painter’s caulk applied to the edges where the glass meets the frame—essentially, it’s just for aesthetic purposes.

On the other hand, however, if your home is clad in wood siding and you’re installing wood framed windows, you may need to do a little more work to prevent leaks and moisture infiltration. You’ll need to securely seal all the gaps using clear silicone caulk rated for exterior use.

vinyl window frames

Where Should You Never Caulk

Don’t get too crazy with that caulking gun—there are definitely some places around your windows where caulk should never go. While it may be tempting to seal up any and all gaps you see around your windows, some of them may be necessary to vent excess moisture from behind your window trim.

One place you should avoid caulking at all costs is the window’s weep hole. This small hole at the bottom of the exterior frame in vinyl windows allows moisture behind the window to exit through the frame. If you plug this hole, you could cause mold or rot to grow unchecked.

Another area that confuses some homeowners is whether or not they should seal the joints where the window trim meets the siding. In this case, the true answer is, “it depends.” If the trim sits flush against the siding, then yes, by all means, it should be properly sealed. Caulking these joints with weather-proof silicone caulk keeps moisture from getting behind your siding, which can cause all kinds of havoc with your home’s interior walls.

On the other hand, though, in many modern homes, the windows are trimmed out so that the trim sits above the siding. The cladding is carried out to the edge of the window frame, in this case. In this situation, it isn’t necessary to seal the joints—in fact, it will harm your windows, since this acts as a channel to carry excess moisture away from your siding and windows.

Lastly, you should typically avoid caulking above the window frame, no matter what kind of window you have installed. This spot is known as a drip edge, and its job is to carry rain and snow away from the windows and siding. If you close off this joint with caulk, it can cause moisture to become trapped behind the frame and the edge of the siding. Again, that often spells big trouble for your home’s exterior walls and your window frames down the line. So do yourself a favor and keep this spot seal-free. You’ll thank yourself every time it rains.

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