Hello,

I've attached the rough-in layout of my basement bathroom. Fortunately, I had pictures while the house was being built so I know the layout of plumbing underneath the slab. I've indicated these drain lines as well. Hopefully the picture and my probable misuse of terms in this email all makes sense. (I'm a novice at this)

What everything boils down to is that when they built the house, I think they roughed in the trap riser for the tub about 3.5" off. Additionally it looks like they installed a steel support column in the wrong place as well.

Here's my plan, let me know if I've made a bad assumption or if you think things could be could be done better.

1) According to the plans provided by the builder for the optional finished basement, the wall to the left of the sink should be aligned with the steel support column and in my basement it's about 5" off. - No big deal, I can bump out the wall to meet the 15" lavatory code requirement.

2) When I align the back wall of the bathroom to be about 13" from center of the toilet drain line, the tub drain line is about 3.5" offset from where it needs to be. (From the picture you can see I have a scrap 2x4 between the back wall and the tub drain cap). I am fairly certain the tub drain was J-trapped underneath the concrete slab. - My plan here is to simply bump out the back wall by 3.5" to accommodate the tub drain and for aesthetic reasons add another 3.5" on the opposite end of the tub as well.

3) If I add 3.5" wall bump out for the tub, the steel support beam that is 60" from the back wall of the bathroom will also have to be boxed out as well. - Not exactly the most pleasing layout, but there's not much I can do about that steel support column.

4) Since my clearance between my toilet and tub drain stubs is barely 30" (I hope an inspector won't be too picky about 1/2" off), I want the wall bump out that accommodates the tub drain to be the same width of the tub (30"). Will I have trouble tiling this bump out if I make it the same width as the tub? In most pictures I've seen of 3-wall alcove tubs, the side walls return a few inches to the tub.


Of course my other option is to dig down and try to add a few 45's to move the tub drain line 3.5" back, but I feel like that's going to require a lot of digging and the trap may not be low enough for me to offset the tub drain line enough. I think I'd need a small run between the 45's and I think that would need at least 12" below floor line to accomplish the offset.

Any words of wisdom or suggestions would be greatly appreciated.

Thanks
Mike
Attachment 5737

first, let me say, you are the most informative post I have ever worked with, love it.
1) According to the plans provided by the builder for the optional finished basement, the wall to the left of the sink should be aligned with the steel support column and in my basement it's about 5" off. - No big deal, I can bump out the wall to meet the 15" lavatory code requirement.
... answer... I think the lav area you currently have will allow a 27 inch vanity. You must maintain a minimum of 15 inch from the center of the toilet to both sides [elbow room]. You also can leave the lav pipe where it is and using a cabinet it will easily hide a tee and studor vent to vent the entire bath piping, all under the lav, no vent in the wall.

2) When I align the back wall of the bathroom to be about 13" from center of the toilet drain line, the tub drain line is about 3.5" offset from where it needs to be. (From the picture you can see I have a scrap 2x4 between the back wall and the tub drain cap). I am fairly certain the tub drain was J-trapped underneath the concrete slab. - My plan here is to simply bump out the back wall by 3.5" to accommodate the tub drain and for aesthetic reasons add another 3.5" on the opposite end of the tub as well.
... answer... the finished wall veneer must be 12 inches from the center of the toilet drain pipe. Most rough the toilet at 12.5 inches from the wall for drywall. I would not bump out the wall where the tub faucet is going. It will cause problems for the toilet clearance and not look well. Do all the furr at the other end. Some folks even put a shelf just above the tub for plants or shapoo. If you do, make sure no water can stand on it and run down in the wall. Note... the tub wall should be at least 45 inches to the right of the center line of the toilet drain. The tub drain riser can be offset to make it work for the tub to set against the wall with no bump out.

4) Since my clearance between my toilet and tub drain stubs is barely 30" (I hope an inspector won't be too picky about 1/2" off), I want the wall bump out that accommodates the tub drain to be the same width of the tub (30"). Will I have trouble tiling this bump out if I make it the same width as the tub? In most pictures I've seen of 3-wall alcove tubs, the side walls return a few inches to the tub.
... answer... the tub edge should be a minimum of 15 inches from the center of the toilet drain pipe to be legal. You will have that. You will have trouble tiling the bump out.

I think I see a 3 inch toilet riser. You have a 4 by 3 toilet flange. This means you will be chiselling out concrete. Ask your plumber if a 3 inch inside flange is legal there. It glues inside the 3 inch pipe.