Bathroom Re-model Layout Advice #2

[ralft]

This post has lots of similarity to CJT's of 7/19/06. I have attached (2) sketches as .JPG files showing what exists and what we want to do. Our goal is to make the tiny 2 room bathroom into a larger single room. At the same time we would like to incorporate a free standing vanity with a wall mounted faucet and a claw foot tub.
We like the idea of having the claw foot tub under the window and have positioned it accordingly. Since we are on a concrete slab which we strongly believe is steel reinforced, the only way I think we can do it is to route the drain line under the tub and through the wall under the window. We would put the "P" trap outside in an a access pit with a cover. Does anyone see a problem with this.
We really wanted to put the toilet further to the left but have it situated so its outlet is within the confines of a pit under the tub's present location. Our thinking is that we can dig out under the slab and connect the sewer lines accordingly.
We realize that it will be lots more work when we are relocating the tub and toilet but just want to know if it seems practical. We aren't architects or contractors, just homeowners. We may do the work ourselves subcontracting the more difficult parts.

[jadnashua]

The P-trap needs to be under the tub. Running that long line to it would allow crud to accumulate and it would quickly start to smell, and it would not pass code. Unless the slab is a post-tensioned slab, where cutting a cable is likely to cause the slab to fail, while a pain, it is fairly common to cut reinforced slabs to move things around. There are various ways to add back in reinforment steel prior to refilling the holes you make. If it is a tensioned slab, then you need a structural engineer.

[ralft]

The P-trap needs to be under the tub. Running that long line to it would allow crud to accumulate and it would quickly start to smell, and it would not pass code. Unless the slab is a post-tensioned slab, where cutting a cable is likely to cause the slab to fail, while a pain, it is fairly common to cut reinforced slabs to move things around. There are various ways to add back in reinforment steel prior to refilling the holes you make. If it is a tensioned slab, then you need a structural engineer.

Thanks jadnashuafor the quick reply. There is no possiblity of my slab having post tensioning cables because of its age (45+ years). Butm there would certainly be a rsik to slab damage if I have the hole drilled. I live in the Houston, TX area where slab cracking is a common occurence because of unstable soil conditions.
Now I have a new idea. The toilet's vent pipe must be in the wall between the bathroom and the master bed room. Shouldn't I be able to fit a P-trap between the end of the tub and the wall but above the floor. Then I would discharge discharge the water into the old toilet vent line? I have read somewhere that the horizontal drain line is 4" above the floor so it seems like I should be able to make a 1 1/2" P-trap compact enough to fit. If necessary I could chip out the concrete to make a little depression for the P-trap to lay in.

[master plumber mark]

dont be a worry wart about that slab floor...

if it is 45 years old its done all the settling its going to be doing by now....


you are going to be moving quite a lot of drain lines here

according to your second propopsed postt

and its all going to have to be torn out to some extent...

you will most likely run into "steel mesh" in the floor if the floor

is that thick. 5-8 inches... OUCH

... the steel mesh usually just needs to be cut out of the way

with some heavy duty cutting snips and you are good to go...

and you might get lucky and it be only 3-4 inches thick....




because you are going to be doing some trenching under that slab to

get the pipes where you want them a LOT of concrete is probably going to

have to be displaced here....

your biggest concern is where the water lines are....if they are over head

its no problems at all.... if they are in the slab then be careful, careful careful....


just make it big enough to work with then re-fill the hole back in with some sand and about 4 inches of finishing topping concrete
and you are done..


if you are really worried about movement or cracking...throw some
rebarb back down into the trench after your plumbing is through

sometimes you just have to do what you got to do----to win the battle----.


just tear into it and if in 30 years if cracks start to form.... just call me a dumb ass---