Vent pipe through the roof...

[hhcibtpaun]

Quick question on the size of vent pipe I should run through my roof.

I have a basement bathroom with tub/shower, toilet, sink and bar sink. The bar sink has a grey water pump and there is an ejector pump. Pretty much everything is vented with 2" pipe, and all those go into a pre-existing 3" pipe that the builder had put in. This 3" pipe goes up 2 stories to the attic. Can I neck down the last 6 feet or so, to go through the roof with 2" pipe or should I stick with 3"?

Also, do I was planning on protruding through the roof about 12-18"...

So, 3" or 2" through the roof?

Thanks...Mike

[seaofnames]

I'd stay with 3" with that number of fixtures being vented. Check your building code though, or call your city/county inspector and ask to make sure!

[Winslow]

you cannot reduce the vent, only increase. If you wanted it to be 2" then it needs to be 2" all the way. 12-18 inches sounds excessive. Depending on your local code it is usually less. UPC is 6" min but common practice here in hawaii is to vent thru the roof 10 inches.

[nhmaster]

In northern climates 18" through and 3" diameter is usually minimum.