Minimum Roof Vent Pipe Diameter

Hello Forum!

During my summer project dubbed "Cast Iron Man", where I'm going to attempt to replace all the CI in my house with PVC, I'm going to run a proper vent for my basement sump pit. I believe I need to have a separate vent (not connected to the existing roof vent) that goes from the sump pit, all the way through the roof. The pit has a cutout with rubber seal for 1 1/2" PVC, but I'm thinking that is too small to go out through the roof. Internet results are mixed, with some saying a minimum 2", and others 3". It seems like reducing the pipe diameter in the attic/wall would potentially cause a choke point if any debris happened to get into the pipe. Can anyone tell me what the minimum diameter exiting the roof should be? And, the height above the finished roof? I was just going to match the existing CI vent height, but figured I would run it by the crew. Oh, I live in New Hampshire, so there is snow/ice/frost to deal with.

Thanks!

If this is a sump pit for french drain, then no vent is needed. You can seal the pit air tight. If it's for sanitary or building drain, the minimum size is 2" vent and can be connected to the rest of the sanitary venting system (I don't understand why it couldn't...it's not a local vent). If other fixtures connect to it, then the rest of the venting would be sized accordingly to the VFU until it penetrated the roof. There was a sub-soil drain drawing posted recently by...Mr David, I believe...that was spot on for sanitary ejector systems.

I see. Here's what I find on line concerning a sump basin/pit for ground water (I think):

712.3.2 Sump pit. The sump pit shall be not less than 18
inches (457 mm) in diameter and 24 inches (610 mm) deep,
unless otherwise approved. The pit shall be accessible and
located such that all drainage flows into the pit by gravity.
The sump pit shall be constructed of tile, concrete, steel,
plastic or other approved materials. The pit bottom shall be
sohd and provide permanent support for the pump. The
sump pit shall be fitted with a gas-tight removable cover
adequate to support anticipated loads in the area of use. The
sump pit shall be vented in accordance with Chapter 9.

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I tried to read chapter 9, but there's too much info there, and I can't see anything specific to sump pit vents. Strange.

Got the info here: NH Plumbing Code

upc, chapter 7,

the words..."or when permitted" . mean, contact your local plumbing authority and ask about your area

frodo said:

the words..."or when permitted" . mean, contact your local plumbing authority and ask about your area

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Would that be my local city building dept.?

Solid said:

Would that be my local city building dept.?

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yes, usually, call the building permit department, ask for the plumbing inspector.

call early, or late, they are usually in the field doing inspections.

8 am, he is getting coffee,and a dognut



{{{{{could be different office, or department, your area,]]]]]]
call and ask

If you are in an area with frost, the minimum pipe size going thru th roof should be 3". Anything up to the roof line will depend on your fixture load