Copper is the longest-lived, but because it's expensive, we see it only on high-end jobs here. Another advantage to copper is that the corners can be soldered for a watertight connection. In the Northeast, masons are partial to lead flashing, which is soft and easy to bend to shape. But no matter which material is used, it must be layered correctly if water is to be kept out.
When the chimney is at the bottom of a roof slope, we always install a cricket, a small diversion roof that prevents water from pounding the up-roof part of the chimney. We frame and sheathe crickets just like the rest of the roof, and then completely cover them with a modified bitumen membrane, which is folded up under the chimney flashing.
We install asphalt shingles over the membrane to blend the cricket with the rest of the roof. Because chimneys are such a potential trouble spot, inspect them once every year or two for loose or missing flashing and cracks in the masonry. Small cracks can be sealed with caulk designed to repair masonry. I also recommend that my customers waterproof their brick chimneys every few years with a silicone-based sealer that can be applied with a garden sprayer.
Not all builders agree, but this is a great way to keep water from seeping into the brick. Is your roof protected from unexpected damages? As a rule, chimneys are either masonry or metal.
Some chimneys are clad in wood, stucco or aluminum siding. Round metal chimneys will be flashed much like pipes. Chimneys have a foundation, which may be independent from the house. In any case, the roof deck may move relative to the masonry chimney and good flashing details anticipate this.
Good chimney flashings are two-part. The base flashings are secured to the deck and the cap flashing is secured to the masonry. The overlap between these two flashings allows movement without disturbing the water-tightness. Bottom: Before the base flashing is installed, the roof is shingled up to the bottom of the chimney. The bottom base flashing is made of a single piece of metal extending 3 to 6 inches down over the shingles that already have been installed, and 12 inches some say less up the bottom face of the chimney.
This flashing wraps a few inches around the sides of the chimney. Sides: The base flashing for the sides of the chimney is called a step flashing. Others call these soakers or baby tins. The step flashings typically are 3 inches wide, 3 inches tall some recommend wider and taller, as much as 6 inches in each dimension and about 9 inches long.
They typically are the length of the shingle exposure, plus 3 inches some say 2 inches! These base flashings are nailed to the deck. A cricket or saddle is typical on a chimney and is required by many authorities when the chimney width is more than 30 inches. The cricket or saddle is a peak that deflects water and snow around the chimney, preventing it from accumulating against the top side of the chimney.
However, copper is the most expensive option Vinyl or PVC — should only be used in warm weather climates. Can crack under extreme weather conditions. Got a question? Give us a call. What We Offer. Chimney Inspections. Proper maintenance begins with good old fashioned hygiene. Learn more our maintenance process here. Chimney Maintenance. Whatever we find, we can fix. Find out more about our repair process here.
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