Help me install a shower in place of a toilet.
December 1, 2011 12:10 PM   Subscribe

I have two toilets with standard 4" toilet connections, mounted on a solid concrete floor. I would like to replace one toilet with a shower. Have you done this before? How do I do it? What problems will I face?

I can use whatever information you can give me. I understand, for example, that I may have to raise the shower to install a proper trap/vent. But any info, how-to information, resources, etc would be awesome.

Recommendations on shower kits would be a bonus.
posted by fake to Home & Garden (10 answers total)
I am in no way any sort of a plumber but maybe this can give you some ideas?
posted by lungtaworld at 1:37 PM on December 1, 2011

What is under the concrete (IE: dirt or living space)? If you can it would be a heck of a lot better to break up a little concrete around the toilet flange and put your P-Trap under the shower. a 16"x24" hole would be plenty and your new shower would cover the hole. All you'd need to do is rent a small concrete saw and once you've cut the hole break up the pieces with a sledge. Once the pipe is exposed you can cut it off short enough to connect a 4" 90 and then adapt that down to 2" to connect your P-Trap.

Because you have a toilet there already you should be set for venting.

If you are interested in a tile shower check out the John Bridge forums. It is an excellent resource for DIY tile showers and they are very friendly and helpful. The Kerdi system in particular is fairly easy to use.
posted by Mitheral at 1:38 PM on December 1, 2011 [1 favorite]

The supply line will obviously be in the wrong location, and you'll only have cold there. You're going to want to bring in a hot from somewhere. In a house with a crawl space this isn't a big deal but I could see it becoming a huge obstacle for a slab house. Unless you like cold showers!
posted by Big_B at 1:41 PM on December 1, 2011

I can't break a hole in the floor in this location... Is the right solution to raise the shower?
posted by fake at 3:19 PM on December 1, 2011

Also, this is an industrial location so the supply lines can run against the wall with no issues.
posted by fake at 3:22 PM on December 1, 2011

Are you saying you want the shower drain to just hook onto the flange? I don't see how you are going to be able to do that and have a proper P trap to keep gases from coming up.
posted by Big_B at 4:02 PM on December 1, 2011

If you have the headroom, there is no reason you couldn't build a shower on a platform.
posted by Marky at 4:13 PM on December 1, 2011

Without being able to get into the floor, it's going to get messy. You can't just put an s-bend in the built-up part of the shower and dump it into the pipe where the toilet was. S-traps don't meet any code I know of. You might be able to swing an arm from the toilet vent on top of the floor, and have the trap dip into the closet bend space.

Question: you *aren't allowed*, or you *aren't able* to break a hole in the floor?

Is this a temporary thing? And is it going to be permitted and inspected?
posted by notsnot at 5:06 PM on December 1, 2011

fake writes "I can't break a hole in the floor in this location... Is the right solution to raise the shower?"

Pretty well the only solution in that case. There is no P-Trap in a toilet drain line so you'll need to provide that and that means raising the floor at least the height of a P-Trap assembly. I'd plan on ~8" of rise to accommodate the under floor piping. 2X8s on edge would work.

The real problem is joining your new drain plumbing to the toilet flange. I've never seen a fitting for that purpose. Assuming such a thing doesn't exist here's what I'd do:
  1. start with a 4X3 ABS toilet flange. The 4x3 means it is 4" at the flange end and it fits a 3" pipe at the other end.
  2. Cement in a 3x2 reducing bushing (looks like a 3" doughnut with a 2" hole in the centre).
  3. The 2" part of the bushing has a ridge at one end to prevent the 2" pipe from pushing in too far. Remove this ridge so a 2" pipe can slide right through the fitting. A knife or rasp would do the job.
  4. Next slide a length 2" pipe into the reducer so that around 6" is sticking past the reducer on the reducer side and 6" is sticking past the toilet flange and mark the pipe where it meets the bushing.
  5. Slide the pipe out and then spead the solvent cement on the reducer and for the entire length of the 2" pipe on the flange side until you reach your mark. Then slide the pipe into the flange/reducer combo from the reducer side until your mark lines up with the reducer. The cement will set up fairly in short order so act quickly once you have the cement applied.
  6. Once the pipe is inserted correctly give it a 1/4 twist or so to spread the glue between the two pieces.
  7. Once the solvent dries (30-40 minutes) your custom adapter is ready.
  8. Put a serious bead of silicone on the flange on the floor, set your adapter flange onto the silicone (reducer side up), bolt it in place using regular toilet bolts.
The theory behind this adapter is the piece of pipe sticking past the flange into the pipe directs the waste water away from the flange to flange joint. The silicone acts as a secondary water seal and primary vent seal. Can't see how this set up would be significantly different than what the toilet to flange seal with wax ring works.

Once the silicone sets up (24 hours) you can adjust the 2" pipe sticking up so that a 90 coming off of it just clears the underside of your raised floor. Then come across with a section of 2" pipe at least 4" long (to avoid an S Trap) and into your P Trap and then up to your shower drain flange.

Note that this is a pretty, um, unprofessional setup but it should work and it would allow you to re-install the toilet in the future with just a little work to remove the siliconed flange.

You could install what ever style of shower stall on top of your false floor you want. Those one piece acrylic stalls are nice and they pretty well can't leak.

My only other suggestion would be to extend your raised floor in front of the entrance to your shower so that you have at least a 36"x36" landing in front of the shower. It'll be a bit safer than having to step up into and step down out of the shower.

Depending on the length of the run of 4" before it reaches a vertical vent stack you may want to add an Air Admittance Valve to your drain system. Instead of attaching the P-Trap directly to the horizontal pipe attach it the side of a wye and bring the straight through out past the edge of your floor and up a few inches and then attach the AAV. Or use something like this slick setup but because of the requirements of the AAV it would add another few inches to the height of your false floor.
posted by Mitheral at 7:45 PM on December 1, 2011 [1 favorite]

My addition to Mitheral's great suggestion is to make sure to actually attach your new shower platform to the floor (you'll probably have to drill into the concrete, but that's easy to patch later, or even just glue it down with silicone) or the nearest wall. If you just have it sitting out there in the middle of the floor held down by gravity, at some point your drunk friend is going to bounce off of it hard enough to shift it a half inch and break a pipe, which would really suck.
posted by Forktine at 5:56 AM on December 2, 2011 [1 favorite]

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