One of the most difficult elements to predict or control is water. When it comes to water, your roof’s flashing is the last line of defense between you and disaster. It’s no surprise that damaged, worn, or poorly-installed flashing is a primary cause of roofing leaks.
Flashing is a piece of sheet metal, usually aluminum or steel, which is placed over the joints in a roof to prevent water from leaking into the house. It’s most commonly used around chimneys, fan vents, plumbing vent stacks, and anything else that projects out from a roof. When everything is properly installed and maintained, flashing works with gravity to reflect water from the roof onto the ground.
To get the most out of your roof, flashing should be weather resistant and low maintenance. It should also withstand movement, as roofing materials may well expand and retract during periods of extreme heat or cold. Like anything left exposed to the elements (heavy winds, rain, snow, ice, and heat) flashing becomes less effective the more it is tested. Flashing is one of the most difficult, technical, and important components of your roof to get right. When it comes time to repair or reroof, you want to be in the hands of an experienced professional.