I am building a new bathroom in my basement. Plumbing was roughed-in when the house was built. The floor is concrete and there is a rectangular hole (about 15 x 20", to bare dirt) where the "stub" is to the tub drain. The shower base fits neatly over the hole. No problem. Just two questions...

(1) The concrete is not perfectly even around the hole (but it is pretty close). So, the shower base can rock just a bit. Obviously, I want to resolve that. The shower base (Kohler/Sterling, Vikrell) instructions note that "roofing felt" may be necessary to avoid squeaking. Is this my solution to the slightly uneven concrete, or (A) do I need to "shim" it, (B) grind the lip of the hole to even things out, or (C) build a sub-floor over the concrete?

(2) In the hole I need to install a P-Trap that mates up to the shower drain. Then what? Can that hole just be left as bare-dirt? Do I need to fill it and maybe even pour concrete to make a hard flat surface. FYI, we have sandy soil and it is VERY dry where we live.

Thanks for any advice you can give me!

Nick

 

You can do whatever it takes to level the base but whatever you decide, make sure the base does not flex. That is, when you step into it, make sure that although it isn't rocking it also is not bending if you use shims.
The hole does not need to be filled in and if you did fill it you may have problems later if you needed to do any repairs. Bugs entering in the hole would be my only concern. You didn't say how old the house is or if critters had been a previous problem.
Quick question concerning the stubbed pipe. If it was roughed in for a bathtub, it is probably 1-1/2" pipe. Most codes call for 2" for a shower installation. Might want to check on this. Good luck with your project.

 

Our house was a new construction completed in 2000. Its very dry here in Wyoming and bugs aren't a big concern, but that seems like a great place for them to live. I think I am going to fill it with dirt and then "cap" that with a thin layer of concrete (maybe just an inch, so that it could easily be knocked out in the future).

I think I am going to try for grinding/chipping the lip of the hole, AND using "roofing felt" to even things out and provide a semi-soft base. I want to be certain that it does not rock or flex at all when I stand in it. BTW, is "roofing felt" the same as "tar paper," or what exactly am I looking for here?

As for the drain pipe size: I will check it (I think it's 2"). Why would a tub take a smaller pipe than a shower? Seems like it should be the other way around because a tub can drain a LOT of water in a hurry, whereas a shower is limited by the flow at the head. Either way, there is not much I am going to do about it (unless you tell me I am headed for BIG trouble).

Here in the wild-west, my county does not require a permit/inspection, nor can I even opt for one. I know that's kind of crazy, but that's the way it is. I will have a plumber do the water connections (which are also already stubbed-in). I am sure glad I have a friend who is a master electrician checking me on that stuff!

Thanks for the help.

Nick

 

I live in the same type area as you as far as inspections and permits. I have always wondered about the drain size difference also, but never got an answer. Looks like you have covered all your bases as far as getting the shower level and secured. Felt is the same as tar paper. It comes in 2 thicknesses, 15 pound and 30 pound. Good luck.

 

my thought on 2 inch shower drain verses 1 1/2 in tub drain is,maybe they figure a tub can hold 50 or so gallons of water ,where as a shower cant hold much water without over flowing thats why they say 2 inch pipe,so we arent faced with worrying if the shower will overflow while taking a shower...thats the only thing i can think of when it comes to 1 1/2 verses 2 inch ...