Garage Bathroom Drain Plumbing

[bad_idea]

I have a 30x40 building I plan to put a bathroom in one corner of. I have a cinder block stem wall ~16" above grade, with concrete slab in garage, and 2x6 studded walls. I do not want to chip up concrete. I am thinking about doing a raised floor (2x6 pressure treated directly on slab) and exiting the drain pipe out of the side of the building through the stem wall. Install a sweep tee on the outside of the building going down with a clean out on top. Will then tie into the drain line from the house ~15' away. I am on a septic system. Here in northeast NC we do not see freezing temps often. I also assume being a vertical section of pipe that will be exposed to the elements, there should be no concern of freezing liquids in the pipe. I am out in the county and have no intention of pulling a permit. Thoughts? Thanks all.

 

[The Cobbler]

I'd look in to rear exit toilets , some even have small pumps that sinks can tie in to . That way you keep the bathroom at floor level .
saniflow is one name that comes to mind .

 

[bad_idea]

Not a bad Idea. So the plumbing line could then run just above the floor and then exit out the side of the building as planned. I assume the pump would be needed when installed in a basement. I am thinking if I put the sink and toilet beside each other, the sink drain would tee into the pipe utilizing gravity for draining.

 

[bad_idea]

For the water supply, I plan to dig down 12" and punch a hole through the cinder block of the stem wall (block is hollow, not concrete filled). Then cut a 3" hole through the bottom plate to fish a piece of pex into the wall cavity. My concern is the few days a year we get below freezing temps, will the pex line freeze inside the block? I plan to insulate the walls and keep the bathroom at 55 degrees or so all winter.

What is the typical solution to this issue?

 

[Leaflessshadetree]

You also need a vent.

 

[bad_idea]

You also need a vent.

I know. I will route one in the wall cavity, up through the roof. I'll have a roofer handle the penetration through the roof. I have an exhaust vent (for my weld table) that I will also have him cut into the roof at the same time.

 

[housewolf]

Rear outlet - floor mount toilet on exterior wall, most of the major brands have them. Catch the lav drain off the toilet vent

 

[bad_idea]

Rear outlet - floor mount toilet on exterior wall, most of the major brands have them. Catch the lav drain off the toilet vent

Thanks. I was thinking something like that, but not a plumber.

My only concern now is the incoming potable water. I plan to punch it into the cinder block stem wall (12" below grade), up into the wall cavity. My only concern is how to protect the pex in the cinder block from freezing. It drops below freezing a few nights a year down here. Don't want to deal with a frozen pipe.

 

[The Cobbler]

how to protect the pex in the cinder block from freezing

I ran water to my shop ( never hooked it up) with the same concerns .
I am doubtful it is code compliant, but I was going to rig up the following.

I will sketch out a picture , but
snake a 3/8 OD copper tube with end soldered closed into the water line
install a Tee on the top of the incoming line with a slightly modified 3/8 compression fitting so the 3/8 can slide thru it . tighten the compression fitting so the 3/8 line is now water pressure on the OD & nothing in the ID .
into the 3/8 copper slip a length of self regulating heat tape , attached to a thermostatic & gfci controlled plug,

 

[Uncle murph]

For the water supply, I plan to dig down 12" and punch a hole through the cinder block of the stem wall (block is hollow, not concrete filled). Then cut a 3" hole through the bottom plate to fish a piece of pex into the wall cavity. My concern is the few days a year we get below freezing temps, will the pex line freeze inside the block? I plan to insulate the walls and keep the bathroom at 55 degrees or so all winter.

What is the typical solution to this issue?

As long as there are no fittings involved,the occasional short term freezing of pex won’t hurt a thing.

 

[bad_idea]

Nice. I can fish a continuous piece of pex from the tie in under the house to the garage. I plan to have all of the piping in the garage surface mounted on the wall. I do not want fittings in the wall. I would rather have the piping exposed in the bathroom to make modifications easier in the future. I do plan to insulate and sheetrock the bathroom.

I know pex is sensitive to UV, so I will insulate it to keep the light off of it.

 

[housewolf]

Thanks. I was thinking something like that, but not a plumber.

My only concern now is the incoming potable water. I plan to punch it into the cinder block stem wall (12" below grade), up into the wall cavity. My only concern is how to protect the pex in the cinder block from freezing. It drops below freezing a few nights a year down here. Don't want to deal with a frozen pipe.

Why wouldn’t you do same with the waste to the toilet and just do a floor flange? Unless I’m overlooking something, you have to get it through that CMU above or below grade. All things equal, I’d prefer a floor flange than on the wall. Are you going to run the vent exposed too? Make sure you don’t come up behind the toilet or lav. I know it’s obvious but mistakes like that are pretty easy to make when you’re focused on the task at hand and not looking ahead

 

[bad_idea]

This is an image I pulled from the internet that resembles the construction of my building. The stem wall on my building is hollow cinder block all the way down to the concrete footer. The footer is 18" deep. It will be very easy to dig down on the outside, penetrate the block with pex, and then drill a hole through the bottom plate of the wall to enter the wall cavity with the pex.

I do not see a way to do the same thing with the drain pipe without cutting up a section of the concrete floor and pouring new concrete around it.