Georgia Garage Bathroom Slab Help

[AlexanderTheDIYer]

Hello,
I am building a metal building with a single 3 piece bathroom and a utility sink. I have gotten all the permits and now just need to do the work. The dirt work is done and gravel is being delivered tomorrow for the base. The building will be on a 4 inch slab. I have tried to get plumbers but they are all 3-4 months out for something like this. I decided to do it myself. I have read a lot of forums and roughly laid out my plan. Can someone tell me if this would pass an inspection on cursory glance. Obviously everything would have to be primed and glued, berriedand what not but is the plan solid?

I added a photo of my rough job. The pipe would be vertical.

 

[Breplum]

The utility sink and tub drain should both be 2", then the vents can be 1.5". All vents can tie together six inches above the flood rim of the highest fixture.
Check with your inspector as to whether the vent size can be two inch for the system. I know two inch will work, but do what they want.

 

[Sponsor]

 

[AlexanderTheDIYer]

So switch those two out to 2 inch and I should be good? I'll ask about the venting when they inspect. I just don't want to be the reason the concrete guys get held up. I'll try to get a picture of it when I get it dug in. We have some rain today so we are delayed on the rock again.

 

[wwhitney]

A few comments:

- The IPC, which Georgia is under, would allow the sizes as is. But using 2" as breplum suggested would be more robust (and is required by the UPC, which California uses). You could use 2" for the lav drain, too, if that's easier (makes all three non-WC fixtures the same).

- That capped end, are you going to bring it up to grade to an accessible location as a cleanout? One option would be to replace the combo at the end with a 3" LT 90, and put a 3" cleanout tee in the wall low, then use 2" above the tee for the utility sink. Or depending on whether you mind a cleanout sticking out of the wall at a 45 degree angle, use a 3" 45 at the upstream end of the 3" horizontal drain, then a 3x3x2 wye with the 2" inlet vertical for your utility sink drain, and the 3" inlet becomes your cleanout.

- You have 4 dry vent takeoffs, one for each fixture. You have options to reduce that to 3 or 2 dry vent takeoffs, using horizontal wet venting for 1 or 2 bathroom fixtures, but it would complicate the below slab drain layout. So probably not worth it, but just something to be aware of.

Cheers, Wayne

 

[AlexanderTheDIYer]

I will do all three to 2" just to make it simpler. At the end I was going to just cap it but I am now going to do what you said with the cleanout under the sink using a 3 inch tee and then do a reducer to 2 inches.

I saw a lot of people doing the horizontal method but wasn't confident in my ability to get all the angels correct. I think the only negative outside the extra vents is the depth I will have to set everything. For me that isnt an issue as the tank sits 2.5-3 feet below grade and it is a short run to the tank.

When I get back out there I'll doo the suggestions and post some pictures.

Thanks for all the help!