These pesky little roof penetrations are very common sources of roof leaks. There are two major reasons for these leaks, and we will go over these issues. I will provide you with solutions as well as a technique for a leak proof pipe flange/boot, that I will refer to as JHurst flange technique.
- The first being that the rubber gasket has worn and cracked.
- The second reason is improper installation technique.
There are various installation errors that may occur when these flanges/boots are applied. The first and formost error is an issue that I deal with on a regular basis, this erroneous installation procedure is called “burying” of the pipe flange. Burying of the pipe flange promotes water retention, when you want the roof to shed water.
. When installed correctly, the top half of the flange should be covered
with shingles,and the bottom of the flange should be on top of the shingles and visible. There may be
slight differences, depending on how the shingles
are falling. A good rule of thumb to use is to have at least two shingles underneath the pipe flange itself. Some shingle manufacturers recommend setting pipe flanges into roofing cement. In my experience,most good roofers do not use roofing cement on a shingle roof. Using
roof cement on plastic or rubber pipe flanges causes the flanges to break down and fail. Please watch the instructional video below of me installing a leak proof pipe flange.
This is a proper flashing diagram
Pipe flange with rubber seal cracked and broken