View Full Version : Trap arm length

11-12-2004, 02:03 PM
I'm putting in a bathroom vanity sink.
The rough drain is coming out of the side of the wall. The cabinet is 60" and the sink is offset a little, so the middle of the sink is about 36" from the wall where the 2" rough drain comes out.
My question is: Should I extend this 2"-pipe a foot or so before going to the trap arm or should I make the trap arm really long?

If I do extend it should I just glue union fitting or is there another way that's better?

11-12-2004, 03:13 PM
The trap arm is that distance from the trap to the vent. Extending the 2" pipe will still be considered a trap arm. You can cement on a coupling. You only need to be 1 1/2" so you might want to use a 2 x 1 1/2" coupling. You will also need to add some support by the bowl. Strange that a 2" pipe was roughed out.

11-15-2004, 10:57 AM
Is there an advantage to having the trap arm (and trap) 1 1/2 vs. 1 1/4?
The couplings come in a 2" to 1 1/4 or to 1 1/2.
I assume that the tailpiece on the sinks are 1 1/4 and I can use a compression slip fitting that will take it from 1 1/4 to 1 1/2 on the trap and arm.

Seems like a bigger pipe would always be better.

11-15-2004, 11:05 AM
I notice the new avatar like on john bridges site. I presume Terry did that and I thank you terry. I agree with the 1 1/2"

11-16-2004, 09:54 AM
Yes, thanks for changing my avatar.
I'll have to start a new plumbing project so I can keep checking this forum, since I'm almost done w/ my basement bathroom finish.