Plywood required behind TOTO tank in wall?

[Mnoone]

I watched this video about installing a TOTO AP toilet. They mention using 1/2"+ plywood between the tank/carrier and the toilet at about 5:30 in the video.

I haven't heard of this before. Is this actually required? If you were not planning on tiling over that area and instead just having drywall - would you then put drywall over the plywood?

Thank you!

 

[John Gayewski]

Looks to me like they want the "minimum 1/2" plywood". Then whatever the finish wall is.

 

[Sponsor]

 

[Breplum]

If you are not going to tile, actually the plywood can be painted over, or build up the whole wall over it.
If you have drywall only, the pressure of the bowl in cantilever crushes drywall all the time.
Sit on any two bolt wall toilet while facing the wall, and the bowl will wiggle a little and it gets worse over time.

 

[Mnoone]

If you are not going to tile, actually the plywood can be painted over, or build up the whole wall over it.
If you have drywall only, the pressure of the bowl in cantilever crushes drywall all the time.
Sit on any two bolt wall toilet while facing the wall, and the bowl will wiggle a little and it gets worse over time.

In my house I have two wall mounted toilets. Installed 1959. They have tanks outside the wall. Funky things. I had to replace one recently with a Gerber 20-021 (bowl was cracked). The only thing behind the 60 year old toilet was 60 year old drywall (and a metal bracket buried inside the wall, but not pressing against the drywall). It's very solid. But I think it mounts a bit differently than the Totos - the sewer pipe pushes out from the wall (with a rubber gasket in between pipe and toilet) while 4 bolts pull the toilet back into the wall. Whereas I think perhaps with the Toto the only thing pushing the Toto out is the wall (with again bolts pulling it in to the wall).

I wonder if exterior rated plywood would hold up over time in a bathroom, and not look like plywood. Maybe if we did a thin skim coat over the top of it to hide the texture?

 

[Tuttles Revenge]

2 bolt in wall tanks and toilets are not cross compatible with 4 bolt wall hung toilet carriers.

If your 4 bolt toilets were resting against the drywall/plaster, they were not installed correctly even if they seemed solid and never had any problems. They should have been mounted against washers that rested on nuts so that the toilet is about 1/8" proud of the finished surface.

I've never seen plywood used behind a in wall tank wall hung toilet. It would definitely make it a much more solid installation, but finishing it out would be difficult.

The older style in wall tank carriers lacked any crossbar that held the cantilever of the toilet and they often crushed the wall. We started providing our own bracing for those to prevent that issue. the drywall also must contact the frame to prevent any movement. Also some toilet / carrier combos are not compatible as the bottom of the toilet is taller than the cross member and will crush through the drywall.