Chimney flashing repair is one of the most common leak fixes we make in Coeur d'Alene, especially on older brick chimneys in neighborhoods like the Garden District and Fort Grounds. The chimney and the roof move differently, and the joint between them takes all that stress.
A correct chimney flashing has two layers. Step flashing is woven in with each course of shingles up the sides of the chimney. Counter flashing is set into a groove cut into the mortar joint, called a reglet, and bent down over the step flashing. Water that gets past one layer is caught by the other.
What we usually find instead is roofing cement smeared over the joint, counter flashing only glued to the brick face, or metal that has rusted through. Tar looks fine for a season or two, then cracks in the cold and lets water in behind it.
Wide chimneys need a cricket, a small peaked roof on the uphill side that splits water and snow around the chimney. Without one, snow piles up behind the chimney, melts and finds every gap. The residential code calls for a cricket on chimneys wider than 30 inches, and in snow country we like one on smaller chimneys too.
We also check the crown and brick for cracks and loose mortar and point out anything a mason should look at. See also skylight leak repair.
