DIY Home Improvement Forum banner

1 - 4 of 4 Posts

Registered
Joined
74 Posts
Discussion Starter · #1 ·
A new (sewer) vent pipe needs to be installed through a flat foam roof. The house is a (genuine) Eichler, so underneath the foam, the roof must be tar and gravel.

In addition, a new electrical circuit needs to be installed in the same area, which will probably pass through a 1/2" conduit.

What is the proper material and method to seal the vent and electrical penetrations?
 

Registered
Joined
4,912 Posts
On new installations the foam is simply sprayed around the pipe. Then the roof has the final coating and the pipe is caulked where it protrudes through the foam.
You should call a foam installer to see what they recommend. Traditional roof vent jacks may work but sealing them to the foam could present an issue. But rubber jacks and silicone seem to work on everything else.....perhaps that is the solution.
Call a roofer and ask.
 

Registered
Joined
6,719 Posts
I read in this forum that foam can shrink, so simply spraying around the pipe may become a leak. I would flash the pipe with pipe flashing as usual and use the foam to seal around the flashing. In all years, this is the first time reading any post about a foam roof and I don't know anything about it. Just guessing from what I've read about the foam. I'm also wondering if this kind of sealing/repair can be done with a can foam? Can foam has fairly large air pockets and this could be a weakness in sealing ability. You definitely can't leave it as is from the sun damage and probably will have to go back and coat several coats of brush-on roofing.
 

Registered
Joined
74 Posts
Discussion Starter · #4 ·
I called the roofing company. Because this roof needs special tools and materials, this is not a DIY job. The solution is to cut the holes neatly, install the pipe(s), and open a service request for the roofing company to "patch the holes." They said it should be less than $1000.
 
1 - 4 of 4 Posts
Top