What's a Z-Flashing?

One of the more common issues found when inspecting a home is the lack of proper flashing around the windows. Flashings are typically small pieces of metal used to deflect water around or off a structure on a house. They are typically found on the roof and sides of the home. This blog article will discuss Z-flashings around windows.


Any place there is a break in the wall structure can be a potential leakage point on the exterior cladding. A leak that allows moisture behind the cladding can cause problems with the structure of the home. The structure is usually wood and constant water intrusion will eventually rot the wood and deteriorate the structural integrity of that portion of the home.

Windows should be installed with at least two Z-Flashings installed above the window. The first flashing should be installed under the outside cladding (i.e. brick, siding, etc.) and over the trim installed around the window. This would allow water to run down the outside of the siding and onto the top of the Z-Flashing, then down the drip edge and onto the ground or onto the trim.

A second Z-Flashing should be installed under the window trim and above the window itself. Water running down the trim, will then drip on the second Z-Flashing and run down the edges or off the drip edge.

The image below is an example of correct installation of Z-Flashings around a window.

Window Flashings

If Z-Flashings are not present on an existing home, a homeowner can inspect the top of the window and apply caulk to help seal up and prevent water from entering behind the trim or window.

Boxer Inspections is always available to help a home owner to inspect and recommend any needed repairs or issues.

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Sugar Land, Texas 77487