I'm reconfiguring plumbing and need to poke a new vent through the roof of my Chicago two-flat. It's a built-up roof of tar, felt, etc., with a slight grade. How to finish the roof portion so that there are no leaks?

The vent will be of PVC and will connect to a kitchen DWV system. I see many rubber collars available at the hardware store most expressly prohibit use with built-up roofs.

I intend to upgrade the roof but I'd like to be able to wash my hands first. Is this the kind of repair only a roofer can do?


As a temporary fix, spread a layer of Henry Roof Patch around the area where the Pipe Flashing will go. Then press the boot down into the cold patch. Install a screw into each corner and attach the boot to the roof. Make sure the screws are long enough to go into the decking material. Spread some cold patch over the entire boot, especially the edges and at the top. Then cut in some Glass Fabric Membrane at the edges and top. Finish it off with a second coat all over the boot. I usually tar all the way up the pipe and lip down inside the pipe as well.

Henry Roof Patch

  • To be clear, the flashing piece won't match the diameter of the PVC pipe exactly, but it's ok to use the patch material and membrane to seal that gap?
    – alesage
    Feb 20 '19 at 15:17

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