Ask Me Help Desk - How to run the drain pipes? Is 90 degree OK?

I'm in the process of replacing some galvanized pipe with PVC, but I'm unsure of the best way to run the drain.

A shower drain of 1 1/2" galvanized pipe runs with a couple of smaller 1/8 bends and then makes a 90 degree bend before a vertical sink drain of 1 1/4" pipe is connected to this line , which then runs about 4 feet before it connects to the main stack.

I have replaced the 1 1/4" sink drain with a 1 1/2" PVC and I now need to connect the shower drain and the vertical sink drain.

Is it OK to "remove" the 1/8 bends and just run a straight 1 1/2" PVC then make it turn 90 degrees as the sink drain is connected?
Not sure if a 90 degree turn is too much because the sink drain is in the same spot. The drain is horizontal with a slope of probably 1/4" per foot.

A drawing is attached.
By the way, I cannot replace all of the galvanized pipe due to space issues.

Thanks!

If you're going to all this trouble, you should consider upgrading the size of the drain line to conform with modern Plumbing codes.

The shower drain, trap and trap-arm should definitely be upgraded to 2" -- And you'll have fewer problems down the line if you upgrade the lavatory drain to 2" as well.

As for eliminating the combo that makes up the clean-out, if it's accessible, you should install a new clean-out at the end of the run, if it isn't accessible, you should pick up the shower first and the lavatory last, and then install a clean-out tee just under the sanitary tee of the lavatories p-trap.

Trust me, if upgrading/upsizing the line is an option, you'll be very happy you did so.

Quote:

Originally Posted by iamgrowler

If you're going to all this trouble, you should consider upgrading the size of the drain line to conform with modern Plumbing codes.

The shower drain, trap and trap-arm should definitely be upgraded to 2" -- And you'll have fewer problems down the line if you upgrade the lavatory drain to 2" as well.

As for eliminating the combo that makes up the clean-out, if it's accessible, you should install a new clean-out at the end of the run, if it isn't accessible, you should pick up the shower first and the lavatory last, and then install a clean-out tee just under the sanitary tee of the lavatories p-trap.

Trust me, if upgrading/upsizing the line is an option, you'll be very happy you did so.

The problem is that I cannot access the entire drain from the tub-shower.
Would it make sense to replace what I can with 2" and leave the rest as 1 1/2"?
I looked at bath drains (the plug and immediate drain from the tub) and they all seem to be 1 1/2". How would I connect such a drain to a 2" P-trap?

I am planning on installing a cleanout just below the sinks and also where the existing clean out is.

Thanks again!

Quote:

Originally Posted by fcandreasson

The problem is that I cannot access the entire drain from the tub-shower.
Would it make sense to replace what I can with 2" and leave the rest as 1 1/2"?
I looked at bath drains (the plug and immediate drain from the tub) and they all seem to be 1 1/2". How would I connect such a drain to a 2" P-trap?

You didn't specify it was a tub/shower in your first post, so I assumed it was a shower only.

You are correct, an 1-1/2" trap for a tub or tub/shower is the norm.

If the line going into the stack is one of the inaccessible parts you mention, then just leave it all as 1-1/2" -- Telescoping on the downstream end is the last thing you want to do.

Quote:

I am planning on installing a cleanout just below the sinks and also where the existing clean out is.

Technically you don't need the clean-out on the lavatory if you have a line clean-out, but if you have room to do so, then go for it.

Thanks!
I'm sticking with the 1 1/2" then.

Interesting to me that a shower requires a larger drain than a tub... I don't really get the logic behind that... but obviously I'm not a pro :)

Thanks again! All help is highly appreciated!