Sink Rough in

[MarkE]

Plumbing Guru's, I'm working on a bathroom remodel and am about to replace the sink drain pipes to the vent stack. I've got the old pipe removed and am ready to replace it but I wanted to get some advice on what size to use. It looks like the old brass drain was about 1.25", is there a new standard size to use here?

[hj]

It depends on how far you are going to replace it. 1 1/4", unless the drain is ancient, was seldom used for anything other than the final connection. 1 1/2" or 2" was the usual drain pipe size.

[MarkE]

I wouldnt doubt the original pipes were the wrong size, these old houses in my area were really thrown together, built well, but not finished well. Great, I'll use 1.5. Thanks!

[MarkE]

I just realized the threaded female connection to the vent stack is only 1 1/4", is there any benifit to using an adapter to utilze a 1 1/2 pipe just to be converted back down to a 1 1/4" at the p trap, or should I just use 1 1/4 all the way from the vent?

[Dunbar Plumbing]

Can't increase that pipe size then reduce it at the stack. You'll have to keep it 1.25" all the way.


Big box stores sell that smaller pipe.

[MarkE]

Got it, thanks for the quick response Rugged.

[hj]

IT must be a real "hack job" because I have NEVER seen a drain tee with a 1 1/4" opening. If it is a straight galvanized "water line" tee, then it is the wrong fitting anyway and should be replaced. Can you shoot us a picture of the tee?

[MarkE]

Here is a pic of the vent stack on the left I've already removed the 1 1/4" pipe on the right it goes to the bathroom on the other side. I'm going to be replacing both. I cant find a p trap converter for a 1 1/4" pipe, so I might have to use 1 1/2" pipe from the stack. Will there be any issues with this?