toilet and bathtub drain hookups in a slab....

[MikeT]

Now that my rough plumbing is approved, I need to finalize the plumbing in my slab.  When I poured my slab, I left out two 18"x"18 voids for my ABS pipe for the toilet and bathtub.  Now I need to fill it in.

For the tub, once I have what I think is the right location for the drain trap, should I fill most of the void with sand and then cover the rest with concrete, perhaps a 1" layer"?

And for the toilet, will the plastic flange need something below it for the bolts?  Perhaps like some buried PT wood on each side of the toilet?  Am I over thinking this?

mt

[n74tg]

Seems like in so many houses I've watched being built, they did nothing to fill the hole around the tub.  And yes, I've heard of peoples termite problems coming from that hole under the tub.  Nice, moist environment, great termite potential.  I'm hoping what I've seen is just examples of poor quality construction and that somebody, somewhere does something to cover the hole.

Now as for the toilet.  I think what I've seen is people buried the ABS before the slab was poured, so the stub out had concrete right up to the sides of the pipe.  Personally, I can't remember seeing anybody do it the way you did; not saying it's wrong, I just haven't seen it.

[MikeT]

Maybe I didn't explain what I did clearly.

With the tub, I plan on filling in with concrete, but I need to be absolutely sure I have the trap in the correct place.  And in case I ever need to break it up, my thought is that a thinner layer of concrete would be better.

With the toilet, I can easily just fill in with concrete all the way around the closet 90.  But I will need to secure the toilet and was thinking that it might be better to have the screws go into wood, rather than using anchors, but again, I could be over thinking it.

mt

[glenn kangiser]

That would work fine, Mike, or if you have access from the exterior you can hook it up then grout around it with a sand and cement mix after you fill the hole with sand - like a stucco layer on the top.  It will fit for sure that way.

I use an ABS toilet mount with a swivel metal plate on it - or a slotted ABS mount would work too if placed properly then anchor screws through their mounting brackets into the concrete grout.  The toilet bolts slip into the slots.  Likely there are other ways to do this also.

[MountainDon]

Toilet: The toilet mounts to the toilet flange on the pipe with two brass bolts. They have special heads that slide into place when the toilet is mounted. My slab floor simply has the ABS pipe coming up through the poured slab with the top of the flange set to the height of the finished floor, more or less. No screws, bolts or anchors. The toilet is then secured to the flange with two brass flange bolts. The was seals come in different thicknesses to accommodate different situations.

Tub: I left an unfinished, unconcreted square in the floor when I remodeled the master bathroom. Then when I was ready to install the tub I did my final measuring, cutting and glue up of the tub drain. After checking that it fit, I removed the tub and put a couple inches of concrete in. Like you I was wondering about repairs. Realistically though that is not going to be a very likely need.

And yes, termites can and do take advantage of things like open spaces around pipes through the slab, but they don't need more than a fraction of an inch.

[ScottA]

We never put concrete in the tub hole. Plus the drain/overflow has to be installed with the tub already set so you'd need to concrete it after the tub was in from behind. No reason you can't do that just that it's probly pointless. As far as termites go if you have a slab on grade you'd better have the perimeter treated by an exterminator. If it's a raised slab then you're unlikely to have any problems.

[MikeT]

Thanks for the helpful and prompt responses on both questions.

mt

[Billisnice]

I termite proofed the slab floor...

[MikeT]

Scott:

In thinking about your last comment, a light went on---I was constantly puzzling over how I was going to get the drain and overflow connection where I want it, and then read your comment.  Since I am installing a clawfoot tub and I do not have a the wall drywalled as yet, I should be able to set up the tub with the drain piping, get it right where I want it, and then I can sand plus cement it in place.   I was thinking I had to guess and be right or I would be doomed. 

I love Countryplans and the helpful participants!

mt

[eddiescabin]

I also have been contemplating the drains etc for a bathroom on a slab...was thinking for ease and repairability possibly mounting the toilet and tub on a riser/platform...any thoughts?

[MountainDon]

I would not bother with that. It is very unlikely you will ever need to get into the slab. We've lived on a slab for 25 years. Our only reason to ever contemplate getting into the dlab was because of the PB piping. Use abs/pvs waste and pex supply and there's no reason to worry if it's installed correctly.