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 NJ contractor since 1994, and a father, and husband. Contact me for all your construction questions.

Tuesday, February 01, 2011

Chimney Flashing

Your typical home chimney over time around the foundations move in different directions, thus causing a gap. When this happens it is important to create a barrier between the roof and the chimney. This will make it waterproof as well as flexible, avoiding leaks. The procedure for this is placing chimney flashing, a thin metal barrier made from aluminum, stainless steel, or copper. The sheets wrap around the chimney where the shingles and chimney meet. Rainfall is than directed to flow over and away from the chimneys gap. There is three parts to flashing a chimney. First is base flashing, which is installed in the lowest part of the front of the chimney. This type of flashing is a single sheet of flashing, extending over the front and wrapping slightly around to the sides. Second is step flashing, which is installed along the sloped sides of a chimney. This flashing creates the first layer that will protect your chimney. Typically extending under the shingles that are along the chimney. Third is cap flashing, which is mortar at the joints above the step flashing. This flashing extends down over the step flashing, which provides protection from rain. In the upper back side of the chimney flashing provides a special situation. Chimney's wider than twenty four inches need to be constructed next to a steep roof. This is called a "cricket". It is a dormer installed behind the chimney that directs the rain and snow around the back of the chimney. Chimneys that are narrow, or shallow have a continuous flashing called "backer flashing".