Installing Vinyl Windows and Avoiding Leaks

How to Install Leak Free Vinyl Window Replacements

By Mark J. Donovan

Many homeowners with older homes are finding themselves today replacing their old windows with vinyl window replacements. In many cases the old wooden windows are no longer functional or the window sashes have simply rotted and/or are severely checked.

It’s important to install vinyl widows properly to avoid leaks. Often they’re installed incorrectly and the homeowner finds water dripping down the interior of their walls during rain storms or small puddles on the window sills or floors adjacent to the newly installed vinyl windows.

Key to a successful leak free vinyl window installation is properly flashing and sealing it.

For example, as part of the vinyl window replacement installation a thick bead of water proof sealant should be applied all around the outside face edge of the original window frame. I highly suggest using a 100% silicone caulk, although latex caulk can also work. Silicone caulk is significantly more expensive than latex caulk, however it is much more flexible and less apt to dry out and crack. Also keep in mind you’ll probably need 2 to 3 tubes of caulk per window depending upon the size of the window.

When caulking around the exterior of the window frame keep in mind that caulking around the top of the window is most critical. So if you’re going to skimp anywhere on the application of caulk, don’t do it on the top edge of the window frame. If you want to skimp at all with the caulk, use the silicone caulk on top of the window frame and the latex based caulk on the sides and under the window frame.

Also, if installing the vinyl window in a clapboard sided house, make sure to install Z-strip flashing above the window frame if it is not already there.

The Z-strip flashing will ensure no water gets behind the window frame and underneath the clapboards.

Once you’ve applied caulk around the window frame, next install the vinyl window replacement. Place the new vinyl window into the window frame opening and make sure it is plumb and level. With the aid of a second pair of hands have someone hold the vinyl window firmly in place while you fasten the window to the window frame with non-corrosive screws.

Once the window has been screwed into place go back with your caulking gun and caulk around the exterior lip of the vinyl window to ensure a leak free window. By effectively sandwiching the new vinyl window replacement lip with caulk you will ensure a leak free window.

After the caulk has had time to fully dry, go back a week or two later and check around the window frame to ensure that there are no gaps in the caulk. This can often happen if you are installing vinyl windows in a stucco sided home or any other rough surface house siding. If you find any gaps, fill them with caulk.

So that’s all there is to it for installing vinyl windows and avoiding leaks. Good luck with your vinyl window replacements.

Installing a New Window Ebook

If you need more help on choosing the right window replacement for your home, contact one of our pre-screened window installation contractors. They can help you select the replacement windows that are right for your home and budget, and perform the installation.

For more information on Installing Replacement Windows and Interior Window Trim

  • See the Installing a New Window Ebook from  The Installing a New Window Ebook provides easy to understand, step-by-step instructions, on how to remove an old window and install a new one. Pictures are included for every key step in the process.
  • See the Installing Interior Window Trim Ebook from  The Installing Interior Window Trim Ebook provides easy to understand, step-by-step instructions, on how to install interior window trim around a window. Pictures are included for every key step in the process.

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