Lisa Childers
New Member
I’m converting a half bath to a full bath. Built in the 1940’s, in a basement with a concrete floor and original 4” terra cotta clay drain pipe. Building out new studded walls in place of plaster on block and changing the location of everything meant of course digging up the floor, tearing out the old clay and replacing with PVC. There is a 2” vent stack going through the roof and its location didn’t interfere with any other designs so I decided to continue using it. The original design connected the vent to the bottom of a 90 degree elbow below the commode flange (which is no longer there due to necessary demo work).
We went from the incoming 4” clay directly to a 3” PVC with both the sink drain and the shower drain dropping down to 2”. The vent stack is now going to connect to the 3” main line instead of at the 90 below the commode.
I’ve attached a very simple diagram of the design.
I want to know of any issues anyone sees with this setup. (notwithstanding the lack of scale and proper fittings) Will it provide sufficient venting to the new system? I can't imagine changing the vent from the 90 degree elbow to about 6" further would make any difference. And it supplied sufficient venting for the original design of commode, sink, wall urinal and floor drain. The only difference was they all connected back towards the door in the blue shaded circle area through 4” wye branches.
Comments please? And thanks in advance.

We went from the incoming 4” clay directly to a 3” PVC with both the sink drain and the shower drain dropping down to 2”. The vent stack is now going to connect to the 3” main line instead of at the 90 below the commode.
I’ve attached a very simple diagram of the design.
I want to know of any issues anyone sees with this setup. (notwithstanding the lack of scale and proper fittings) Will it provide sufficient venting to the new system? I can't imagine changing the vent from the 90 degree elbow to about 6" further would make any difference. And it supplied sufficient venting for the original design of commode, sink, wall urinal and floor drain. The only difference was they all connected back towards the door in the blue shaded circle area through 4” wye branches.
Comments please? And thanks in advance.
