The drawing above shows my basement. Currently the basement is not finished. The plumbing is roughed in. It has the shower drain, toilet, and a bathroom sink drain. I also want to install a sink (Labeled in the photo). The sink would attached to the 3 inch stack near it?.

The problem is I am not sure on venting, Do I need to add venting to the bathroom? The two inch pipe only comes up about half way up the wall, and there does not seem to be any venting close to the bathroom. There is a capped pipe hanging down between the floor joist (labeled on drawing), is this most likely a vent pipe? Do I need to vent the sink on the left wall if its closer than 12 feet?

My second problem is an upstairs tub, it makes a horn noise when the hot water is turned on. The water never gets hot it only gets slightly warm. When just the cold is on there is no horn, and the water is cold. Thanks for any help!


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Yes, the 2" pipe that's between the floor joist is a vent. It needs to be connected to the 2" pipe that's halfway up the wall. There may be rainwater in the vent when you cut it, be prepared. The other sink will also need a vent, no matter how close or far it is from the stack. Just run it up and tie into the horizontal vent you're going to run along the floor joists.

Awesome thanks for the reply.

If I am adding a drain into the 3 inch stack using a 3 x 2 wye connector, are you usually able to cut and get the wye in? or will i need some sort of special connector.

sometimes the stack can be lifted a couple of inches to allow sliding a fitting in and sometimes the stack is rock solid and you need special "repair" couplings.
( a repair coupling is just a coupling with no stop in the middle. it will slide all the way over the pipe and back half way)