ejager Posted September 29, 2018 Report Share Posted September 29, 2018 So I've always understood that the bottom half of roof flashings for penetrations should be visible; at the very least the bottom third if the rows and shingles don't align for more exposure. During the inspections on new(er) roofs that I do here in Calgary, the exposure has steadily decreased over the past 10 years, with some instances of none! What does the brain trust here have as opinions and supporting documentation? The Youtube stills are from a video from Canada Roofing Contractors Association/ BuildCanada (https://youtu.be/GHhwwsLX_mg) and an IKO shingle install video (https://youtu.be/sBwxw3KsVOM). One other problem with the IKO video is the use of petroleum based sealants (IKO Shingle Stick (a bitumous mastic)) with the poly-propelene roof vents: From the Quote "Roofing tars are potentially damaging to the roof vent and the asphalt shingles. Use of roofing tar will void any warranty on the Duraflo® Roof Vents." http://www.duraflo.com/us/gooseneck-installation-guide/ (Installation guide for many Duraflow products) Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted September 30, 2018 Report Share Posted September 30, 2018 21 hours ago, ejager said: So I've always understood that the bottom half of roof flashings for penetrations should be visible; at the very least the bottom third if the rows and shingles don't align for more exposure. During the inspections on new(er) roofs that I do here in Calgary, the exposure has steadily decreased over the past 10 years, with some instances of none! I think it's the opposite. You should see no more than the bottom half - preferably no more than the bottom third. I'm fine with the side-laps completely covering the sides of the flashings. As for the mastic, yes, it shouldn't be used on plastic flashings or on the top-side of asphalt shingles. Quote Link to comment Share on other sites More sharing options...
Marc Posted September 30, 2018 Report Share Posted September 30, 2018 (edited) The flashing should be installed in shingle fashion. How much of the lower mid-section of the flashing is exposed doesn't matter. Covering up the sides of the flashing is fine as long as the entire lower mid-section is left exposed. JMHO Edited September 30, 2018 by Marc Quote Link to comment Share on other sites More sharing options...
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