Window Water Leaks

How to Find and Resolve a Leaky Window Problem

By Mark J. Donovan

Window water leaks can occur for a number of reasons. A leaky window also means air leaks, which will inevitably cost you more money on your home energy expenses. Windows without overhangs over them are more susceptible to water problems. Every window installation should include ice and water shield around the window frame opening and over the nailing flanges to prevent moisture penetration. Non-corrosive nails should also be used when installing windows.

One of the first things you should check when you observe a window water leak is the Z-strip flashing installed over the top of the window on the outside of the home.

The flashing should be tucked up underneath the siding just above the window and fold over the top edge of the window.

If the window was installed by a fly-by-night contractor it could be missing. Also, if the siding was nailed to the sheathing directly over the window its possible there is a nail hole in the flashing and water could be wicking its way in.

Also check to make sure that the exterior of the window frame has been properly caulked. Make sure the caulk has not dried out or shrunk. If there are gaps in the caulk between the house siding and the window frame, water could be working its way into the home.

Next check the gasket or sealant between the window sash and the window frame itself. If it is permanently compressed or damaged in any way replace it.

Alternatively you can try applying a small amount of silicone caulk around the damaged gasket areas. If the window panes themselves have glazing to hold them in place, make sure the glazing is not old and cracked. If it is replace the old glazing.

Check the window sill itself for damage or rot. If it is a wood window sill inspect it for checking and splitting. Ultraviolet light and moisture can wreak havoc on wood window sills.

When this type of situation occurs water can penetrate into the window sill and down in between the wall. This type of problem will inevitably lead to rot and mold issues.

How to Install a Window Ebook

If these types of solutions do not solve your leaky window problems then you may have no choice but to remove the window and reinstall it properly. Proper window installation should include the use of ice and water shield around the window frame opening, the use of non-corrosive nails or fasteners, Z-strip flashing and an exterior grade caulk.

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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