View Full Version : Vent flashing

06-07-2012, 06:50 AM
I am building a new powder room (toilet & lav) and I need to install a new 1-1/2" vent through the roof. The piping will be PVC. The roof is essentially flat (1/12 pitch) and is a roll roof (composition type sheets approximately 4' wide), with a silver reflective coating applied to reflect solar energy. I am thinking of using a roof flashing which has a galvanized plate, with a neoprene boot that is flexible enough to accommodate the low pitch. Similar to this: 16536
I would using roofing cement, slide on the flashing, then apply more roofing cement, roofing felt around the perimeter, and more roofing cement on top. Does this sound like a good solution?


06-07-2012, 07:25 AM
IT is probably your ONLY good solution.

Tom Sawyer
06-07-2012, 10:08 AM
Will Maryland let you punch an 1-1/2 vent through the roof? Up here we can't use anything smaller than 3"

06-07-2012, 11:29 AM
We are not in the frost-closure area so it is my understanding that the 3" minimum doesn't apply.

06-07-2012, 12:41 PM
Coming from custom home plumbing you are on the right track. Typically you do not even need the flashing with rubber boot, just a galvanized roof jack with mastic is how most roofers complete the seal possibly using torch down. Copper flashing and lead flashings are another option.