# Proper flashing for vent through parapet wall



## oldhouseowner (19 d ago)

I need to replace a vent pipe with a larger size (1.5" ABS). The pipe penetrates the top of a parapet wall. Below the parapet wall is a a flat-ish roof. I'm not sure what the roofing material is here, but it resembles the peel and stick "cap sheet roll" sold by GAF. Photos attached of the existing pipe I am replacing.

*I would like advice for how to properly flash the pipe penetration through the top of the parapet well*. The wall is <6" thick, so there isn't much room for a sheet metal flashing. Plus, I'm not sure those types of flashings are appropriate for a flat surface like the top of the parapet wall - most seem designed for shingle roofs.

The other type of flashing that seems interesting here is a liquid-applied product. I have seen videos on Youtube of this "Turbo Poly Seal" product used as a pipe flashing.


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## oldhouseowner (19 d ago)

I can't tell how the flashing was done for the existing pipe. I believe it was done in the 50s. here's a photo of the underside 5 mins ago after a few hours of rain. No leaks that I can see.


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## oldhouseowner (19 d ago)

Bump. Maybe this isn't the right section? I didn't want to post in the pro sections since I'm just a DIYer.... though if this job is super tricky I would hire a pro.


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## Deerfly (Mar 14, 2021)

A lead pipe flashing would typically get used if the pipe penetrated in the field of the roof area, then flashed/targeted with like material. 
The pic seems to show the pipe penetrating the parapet wall. This area doesn't recieve near as much opportunity for water intrusion as the field area of the roof, so installing that detail may be unnecessary. Seeing it doesn't leak as it exists now, maybe a new coating of roof cement would be fine.
Or
A metal coping over the parapet wall cut to fit the pipe, clean the pipe and apply new sealant or find a pipe flashing with a small base to fasten to the metal.


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