[Stubits]

The way our house is constructed the only option to vent the bathroom outside is through a modified bitumen flat roof. Is there a specific type of vent that can be used? Does something like this work, or is there something better?

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[ballengerb1]

Can you go through the side wall? If not then you can cut through the roof for a 3" single wall pipe with 2 elbows on the end or a rain cap. Add a pipe boot to the pipe just like was used for your plumbing vent stack. You can buy flashing lits for 3" pipes at most home centers.

[Stubits]

Thanks!

Is 3" enough, I thought it was 4"?

Can I use PVC or just single wall pipe?

Thanks!

[21boat]

PVC should be fine unless the manufacturer directions states other wise. Don't know why you need 4" unless the fan discharge is 4"

[ballengerb1]

Agree, use whatever size the discharge is out of the box, usually 3". PVC is fine but do not use 90 elbows, if you must make a turn use 45s or 22.5, each elbow decreases the air flow.