Basic Simple Plumbing Questions

wesc

I appreciate any help in understanding a little more about this.

1. P-traps, S-traps, it's all good except for the one under the shower drain with a slab foundation. Are you supposed to set a P-trap down below the concrete before you pour the foundation?

2. Very simple question Sink drains. You have a 1 1/4" drain, goes to P-trap, then on to the main house sewer pipe. How exact do you go from 1 1/4 or 1 1/2" to a 4" pipe, or even a 3" pipe, if you're only, say, 3 feet from the main 4" drainage pipe? Or, how do you get there at all for that matter. Seems so hard to find things that will fit together right. It's either thick or thin walled PVC pipe, or the fittings are made for it, or you need to go from thin-walled to thick-walled pipe and no fittings are made for it. Any help is really appreciated. I just can't find this most basic info anywhere. Thanks.

USP45

#1 yes. But you still can cut out the concrete and set it. Leave dirt around the riser, about 6" x 6" so the riser will be flexible enough to make the final connection. If you pour concrete around the riser and it is even 1/4" off, you will not be able to move it.

#2 Reducer couplings, or flush bushings. Flush bushings go inside of the hub of another fitting and reduce the pipe to whatever you need
Sink=1-1/4" using a 1-1/4 x 1-1/2 washer goes to 1-1/2" pipe. Then the 1-1/2" pipe goes to a 4" pipe using a 4" x 1-1/2" tee wey.

Mike Swearingen

I am not a pro plumber, just a long-time DIYer, and here's my 2 cents until one comes along.
1. Yep.
2. There are all kinds of plumbing fittings in the various materials used. If you can't find what you need in your big box store, go to a pro plumbing supply place. They can usually make it up dry for you if you have the measurements.
Good Luck!
Mike

wesc

Thanks. Yep home depot didn't have any 4" x 1 1/2" tee's or wye's. I will have to check out a plumbing store, I think they just didn't have much of a selection.

I'm aware of the 1 1/4" - 1 1/2" reducer coupling, but I had one of them want to leak. Finally just used plumbers tape on it since it's temporary housing anyway. I think I heard of a plumbing supply place up the road I'll check out.

Man it's going to be a real pain to get a tub drain hooked up to that trap isn't it? Not but about an inch of clearance under the tub to work in. Surely they make some drain/fitting where I can just hook up the drain and then put glue on and slide it down into place, instead of trying to screw everything together in a 1" space. Hmmm....

USP45

Maybe a 4x2 tee wey, then a 2 x 1-1/2 flush bushing too. But yes, if you go to a plumbing wholesaler they should be able to set you straight. Showers easy, tubs a pain, agreed, no easy way. Bust and scrape a few knuckles along the way. Maybe cut a hole in the wall at the head of the tub so you can get closer to it may help. Make sure that when you do cut out the concrete you cut enough to get the tub shoe in. This is the part that goes from the drain you can see back to the overflow. Also going from the 1-1/4 P-Trap to the 1-1/2 inside the wall uses a threaded coupling with a plastic washer. TIP After you install P-traps tighten the nuts, then fill sink with hot water and let it run out. This will soften the plastic and you can snug it down some more.

wesc

So when I'm deciding where I need to set the drains for the tubs, is there a standard distance from the side of the tub to the drain? Or do I need to pick out the tub before I rough-in the plumbing and measure? Or would I be better off to just get the tubs down before I install the interior walls, so I could move the walls a little if necessary? In one place, I have a large stand-up shower and a whirlpool back-to-back. In another, there is a closet next to the full tub so I could move that wall pretty easily. Thanks.