Posted by: Jack Henry | November 30, 2021

Editor’s Corner: Flashing

I just returned from a very quick visit to the Pacific Northwest, to spend some time with my dad and brother. It was a whirlwind, but I got in a great hike in the Cascade mountains one day and spent a lot of time chatting with the Church men. One morning, I walked into the living room, and I heard the guys talking about flashing.

“What the heck are you talking about? I leave for a second and you’re talking about flashing? Dad, you’re 80 years old!”

“Sorry, kiddo,” my dad replied. “We’re talking about houses and building materials.” My architect father and metalsmith brother were discussing the failures of certain metals and woods when combined with each other. Specifically, they were talking about protecting windows, roofs, and doors with new flashing. After hearing the word flashing 10 times, I finally asked them to explain what, exactly, they were talking about.

In basic terms, flashing is a material used around windows, doors, etc., to prevent water from leaking in, a particularly important consideration when three-quarters of your year is living in rain or drizzle. A more thorough definition from Wikipedia for flashing (unrelated to creepy people wearing long trench coats) is:

Flashing refers to thin pieces of impervious material installed to prevent the passage of water into a structure from a joint or as part of a weather resistant barrier system. In modern buildings, flashing is intended to decrease water penetration at objects such as chimneys, vent pipes, walls, windows and door openings to make buildings more durable and to reduce indoor mold problems. Metal flashing materials include lead, aluminum, copper, stainless steel, zinc alloy, and other materials.

There are over a dozen different types of flashing for the home, for example:

Roof flashing

Placed around discontinuities or objects which protrude from the roof of a building to deflect water away from seams or joints and in valleys where the runoff is concentrated.

Clay tile roof flashing/channel flashing

Channel flashing

Shaped like a “U” or channel to catch water (e.g., where the edge of a tile roof meets a wall).

Channel flashing (wall, flashing, roof, gutter)

Cap flashing (drip cap)

Often used above windows and doors.

Window and screen cap flashing

Chimney flashing

A general term for flashing a chimney.

Chimney flashing

Valley flashing

In the valley of two intersecting roof planes.

Valley flashing on roof

If you are thinking about flashing, the internet can provide a lot of information on how to do it. I’d stick with the home improvement sites to be safe! For other types of flashing, see the Wikipedia site.

Kara Church

Pronouns: she/her

Technical Editor, Advisory

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