Lavatory trap layout

[Gregg G]

New construction, lavatory trap.

So I have just a couple of details to complete the tub/shower - toilet - lavatory DWV install.

This will sound like a really dumb question to you experienced plumbers, but I tend to
wring my hands on the small details. I have a 1-1/2 drain line from the lavatory sink
to a 1-1/2 x 2 x 2 sanitary tee at the end of the toilet trap arm. Terry was kind enough to
look at that drawing and said it was correct. The last connection is to go from the lavatory
sink to the 1-1/2" horizontal drain line in the wall behind the vanity.

If I understand correctly, lavatory faucets generally come with 1-1/4" drain/tailpiece. So if I
use the commonly available 1-1/2" P-trap, I will use a 1-1/4 x 1-1/2 slip joint washer in the
connection from the tailpiece to the top of the P-trap. Then on the exit of the P-trap I'll use
a 1-1/2 washer to connect the exit slip joint to a 1-1/2" trap adapter at the wall. The trap arm
needs to turn 90 deg in the wall to run to the sanitary tee above the toilet trap arm.

Would it be correct to solvent weld a very short piece of 1-1/2" ABS pipe to the trap adapter
and to the Long 90 in the wall? This looks like it will end up sticking out of the wall a few
inches - don't want to run out of space from the wall to the P-trap. I didn't glue the Long 90
in the wall yet, so I could "offset" it a little bit from the P-trap to give myself some room to
rotate the P-trap for a little more room. Is that how it's normally done?

Thanks in advance for advice!

 

[Kreemoweet]

Trap adapters come with both hub and spigot connections to the wall drain pipe/fittings. So, you could have a short
piece of pipe connecting to an adapter with an 1 1/2 hub connection, as you mention. Or you could glue an adapter
directly into the 90 hub. There is no preferred way, it's a matter of what works best in your particular setup.

You also could continue with 1 1/4 tubular fittings all the way from the lav tailpiece to the adapter at the wall. That would be the most common way to do it.

 

[Sponsor]

 

[Terry Love]

The reducing slip joint washer at the tailpiece.
In Washington you can use a medium 90 on the lav trap arm.
Is this on a pedestal? If so, I sometimes use a spigot trap adapter. The one above is a hub fitting for pipe. Normally with a cabinet installation, you have plenty of space to work with.

 

[Gregg G]

This is not a pedestal, will be 36"x22" vanity cabinet.

I have seen "medium 90" pictures, but haven't found any at Depot or Lowes. I did see hub x spigot street elbow at Depot that kreemoweet mentioned. Need to go to plumbing supply like Ferguson's to find "medium 90"?

Sounds like there should be plenty of room with a cabinet, but don't want big hole in wall for hub to stick out and then have to find big escutcheon, eh?