building a toilet platform

haugboss · Jan 6, 2013

I have a garage with a bathroom on a concrete floor. I am wanting to add a bathroom to the second floor. I do not want to cut into the concrete. Can I lift the toilet off the concrete and add a tee between the concrete and the new toilet flange? I would then build a platform to support the raised toilet and bring the second floor drain down and attach to the tee. This seems like it should work. I just want some other opinions.
thanks in advance

Al

havasu · Jan 6, 2013

Anything will work, but will it pass code? IMHO, I'd do a quick saw cut and install the sewer lines properly.

johnjh2o · Jan 6, 2013

If you do that the basement toilet will no longer be vented.

John

phishfood · Jan 6, 2013

I agree with John. Cut the slab, do the installation correctly. Make sure you attach to the drain line on the sewer side of the basement bathroom group.

Caduceus · Jan 6, 2013

Yeah, I'm with the other guys. You don't want your garage toilet to burp, gurgle or in any other way react to the second floor bathroom being used. Especially if it causes the trap seal to be lost after a 2nd floor toilet flush or draining of a tub (large volume use).
It is similar to 'stack venting', but the connection is so close to the garage toilet that there is a risk of being disappointed by the side effects.
If you add a wye under the concrete, be sure to vent 3" all the way up through the roof or connect to an existing 3" vent before it exits the roof to allow for the stack vent and 2nd floor fixtures to have a good balance of atmospheric pressure.

haugboss · Jan 6, 2013

More info.
The only place to cut the concrete and put the tee in would be under the toilet. From the toilet it goes out an exterior wall. So what difference is it whether I put the tee above or below the concrete? The tee will be 8" under the toilet either way.
thanks for the help

Al

phishfood · Jan 6, 2013

Somewhere in the piping arrangement, there is a vent for the toilet. Any other bathroom needs to be attached to the drain line past the vent, and any other fixtures in the bathroom group.