basement bathroom rough in - framing questions

twobabieslater · 12-29-2008, 12:51 PM

I am finishing more of my basement and am not planning on doing the bathroom down there any time soon, but I need to do the framing all now (including the bathroom). The problem is I am unsure of what the different openings / pipes down there are for and what spacing I need to maintain around them. There is a hole in the foundation just over 3 feet away from a 4" PVC pipe coming out of the foundation. On the opposite wall there is some more PVC pipe. I have attached some pictures. From my internet research it would seem that the 4" PVC is for the toilet and the hole is a shower drain. I am primarily concerned about spacing issues. I put up 1" dow insulation on the walls in that area as I did the rest of the basement and that puts me another inch away from the walls. The 4" PVC pipe is now 16" on center away from one wall and 15" on center away from the other wall. This seems too tight for a toilet especially after the framing is in???? The hole for the shower(?) starts 38" away from the 4" pipe and starts 16" away from where the framing of that wall would come out (which would actually be more like 12 inches after the wall is there). Do you think that is properly placed?? My opinion would be just to put in a shower - not a bathtub, but to other end of the hypothetical room (where the smaller vent piping is?) is about 110" away from the wall and that seems far to me, maybe a bath would be better - I need to consider that when I decide where to put the door.

Another issue is that I am using a dricore subfloor in the rest of the basement living space and don't know if I should put it in the bathroom area. If I do, do I just mark where that hole is and I or the plumber can cut it out later? and just put it around the 4" pipe coming up? I am now really questioning putting up the blue dow insulation because of spacing issues away from the wall.

I guess I really need to decide now is -
1) whether I have to take down the dow insulation because of spacing issues
2) whether to put the dricore everywhere and put walls up over it (that is the preferred manufacturers method so if you do get water it can get to the drain - according to their website)
3) how far away from the shower drain the interior wall should be and
4) where to put the door

Can you look at the pictures and give me an idea if I'm right about what these things are and the spacing issues I'm up against? Thanks!

Aggie67 · 12-29-2008, 02:42 PM

Where do I start...

First, I envy you for having a nice little project there. I'm kind of jambed up with redoing some fiberglass insulation in my garage right now. My hot tub surround has to wait until warmer weather.

Next, it looks like whoever built the house did you a sort of favor by roughing in the drains. It would have been nice to know what they were thinking, though. There are minimum clearances for plumbing fixtures, and max distances to the vent, and rules on what can go where, and rules for size pipe can be used for different fixtures and their associated vents. Do you have a drawing of what's under the slab? Or a drawing of what you want?

I'm thinking the drain in the floor is for the toilet. Nobody really stubs up a toilet drain like that above a slab, at least around here, because there's no way to get the flange on and level it to the flooring. Plus you said that stub up was 4 inch, where for a residential toilet, only 3 inch drain size is needed. And that's another question - you know the OD for 3 inch IPS pipe is 3.5", and OD for 4 inch IPS pipe is 4.5", right?

Back to the flange. When we rough in drains under slabs, we box out the area so there's a concrete-free hole in the slab. (I see a messier version of that in your floor.) Then when it comes time to finish, we can set the flange height and pour in the last slug of bag mix concrete or hydraulic cement our selves. So if the one in the floor is for the toilet (which for residential only has to be 3 inch in my neck of the woods), you have room to set a toilet flange. Then there should be a 2" vent coming off the drain line downstream of the toilet, no more than 6 feet away, which might be that stub coming up, but that's a pretty large vent if it's 4 inch like you say. And a shower drain only has to be 2". Maybe it's a cleanout? Really hard to tell.

And I'm not sure what the other end of that room is. Looks like 3 inch with 1-1/4" fixture fitting, which is good for a bathroom sink. But there are two. Any other type of sink should be 2".

In a nut shell, check before you install the toilet. It's illegal to install a shower or anything else upstream of a toilet drain. Plus you need vents per code.

I hate to say it, but I'd have to walk around your basement to figure out what's what. The house looks new. There has to be something somewhere that tells you why they installed that. Check with the town when you pull your permit, or ask the inspector. He may even remember either who did or what's there under the slab. And there might be drawings in your home's file. My first house was built in 1962, and my drawings were still in the file when I pulled my first permit.

twobabieslater · 12-29-2008, 03:56 PM

Inside the 4" pipe is a 3" pvc pipe? Is it possible the four inch one is just around it for some reason? I just dug around in the hole and there doesn't seem to be anything but rock and dirt. I guess I could keep going. I just called the building inspector he is going to look and see if he has the plans and said he'd some look at it if he didn't. He seems to think the 4" is just a sleeve and the 3 inch inside it is for the toilet - so now I'm back to my original quesion - what is the minimum spacing I need around that? Maybe he'll be able to help me more when he calls back. He said I don't need a permit for making the playroom bigger than it is - as long as I'm not doing anything structural or putting in a bedroom. That was a big sigh of relief. As I said before I'm not planning to do the bathroom any time soon so I just need to know where to put the walls. Also has anyone ever used dricore before? the website says it recommends putting the interior walls over it, anyone ever do this?