shower drain

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I really need your help

I converted a tub/shower combination to a shower-only on the second story; I'm ready to do the floor. Here are my questions:

I have an existing 1 ½" ABS drain, which I traced to where it goes into the sole plate on the 1st story. It seems impossible to convert this to 2†b/c it appears that it remains 1 ½ as it goes into the slab. I understand that 2†is required by code. It will not be inspected, however. Am I going to experience any drainage problems b/c my drain will remain 1 ½"?

If it’s possible to leave the drain at 1 ½, my second questions is this:

Should I use a 2†trap or 1 ½†like the original configuration? Naturally whatever size trap I use it will be connected to the 1 ½†pipe


thanking you in advance

NEVER go from bigger to smaller in a drain - it is a major reason for clogs. Now, the fact it goes into the slab is not a reason to not do it right. Going from 1.5" to 2" is an increase of 178% in area. The concern is that there is very little space to "store" water in a shower in comparison to a tub. So, a washcloth over the drain or a clog can quickly cause an overflow. In a tub, it isn't as immediate of a problem.

Unless you have a post tensioned slab, it may not be a big pain to change the line to a 2" one. Depending on where you live, while you may not get a permit and get it inspected, the house inspector when you sell it may note this deficiency and cost you eithera sale, or a significant discount. In the truth laws, you are obligated to disclose known deficiencies.

Aren't the drains imbedded in the slab? It seems like a major undertaking!

Depend on how far the 1-1/2 runs before it get to a larger drain. If it's just below the surface it won't be too difficult, but if it goes several feet, it will be a bigger job. Big job or not, it's the only right way to go. There is a sound reason a 2" drain is required, and it's NOT to please an inspector. It's because of reason already cited in previous answers to you question.

There were plenty of showers installed in the sixties that had 1.5" waste lines.

It's not code, but it will work.
Most new shower heads only put out 2.5 gallons a minute.

It it were new, it would be 2". the price difference between 1.5 and 2.0 is almost nothing.

Mine is 1.5" and is working like a charm. Doing it all again and not limited by existing drain size, sure I would have done 2"

Jason

drain

An 1 1/2" drain is going to get clogged a lot sooner than a 2" one, but since the original builder went "cheap" and used a 1 1/2" riser you might as well stay with it. From your description, he apparently did not even install the required cleanout fitting before it goes into the floor. Run 1 1/2" pipe right to the bottom of the shower and then make the increase to 2" to fasten to the shower fitting.

This is the most helpful group I have encountered. I want to thank everyone who provided me feedback on this frustrating part of my project.

hj said "Run 1 1/2" pipe right to the bottom of the shower and then make the increase to 2" to fasten to the shower fitting." Can I use a 2" inch trap and then reduce to my 1 1/2" drain to avoid possible clogging at the trap itself?

I would use the 1.5" trap and increase to 2" just below the drain.

A snake will find it's way through a 1.5" trap just fine.

One should never go from a large size pipe/fitting to a smaller size. You should only increase the size. This means you should use a 1-1/2" trap in the 1-1/2" line.

thanks again to everyone