Adding new bathroom on slab

[Swamp Dood]

Trying to add a bathroom in my barn... it’s on a slab so I elevated the floor with 2x6 to give me about 9” of clearance.

I am struggling a little with the layout to ensure I have it vented well?

I may have to jackhammer a little chunk or two to fit the trap under the shower drain.

Floor will be 3/4 PT plywood with waterproof flooring applied.

first image - floor plan
second image - partial elevation

Any of the layout look wrong or unreasonable?

 

[WorthFlorida]

Just go with 2" everywhere and do not use 1.5" to the 2" or 3" line. At the sink trap connections use a 2" trap adapter. Using different size washers for the slip nut for 1.5" or 1.25" traps. It will be easier with one size and very little cost difference. The deep sink will drain faster and better into a 2" pipe. Use a 3" closet flange, a 4" is not needed. Toilets trapways are 2 1/8" wide. All of this is draining into an ejector pump, a clean out is probably not needed since you have access from the pit. If you do install it, again 2" pipe.

I'm not a plumber but I believe the the wye for the toilet and the connection for the shower, as shown is not allowed. The shower must connect to the 3" line after the toilet. A shown toilet waste can back up toward the shower drain and clean out. Someone else will probably confirm my suspicion.

https://www.co.lincoln.or.us/sites/..._-_helpful_hints_residential_construction.pdf

https://www.homedepot.com/p/NIBCO-2...RCH=REC-_-pipsem-_-100345781-_-100344161-_-N&

 

[Sponsor]

 

[wwhitney]

What is a "deep sink"?

Virginia uses the IPC, which restricts horizontal wet venting to bathroom groups (and they haven't amended that like NC has, per up.codes). So that would mean the lav (bath sink), the shower, and the WC. Probably not the "deep sink", depending on what that is.

So the kitchen sink and likely the deep sink need their own dry vents, as does the lav. You may be able to use the lav to wet vent both the shower and the WC, but you have to keep the bathroom group drains separate from the other drains if you want to do that. And the lav has to join the WC or the shower individually, rather than having the shower and the WC join each other, and then join the lav. The IPC doesn't require the WC to be the last fixture on the wet vent, unlike the UPC.

Cheers, Wayne

P.S. It's worth taking a look at circuit venting, that might work out better for your layout.

 

[Swamp Dood]

Just go with 2" everywhere and do not use 1.5" to the 2" or 3" line. At the sink trap connections use a 2" trap adapter. Using different size washers for the slip nut for 1.5" or 1.25" traps. It will be easier with one size and very little cost difference. The deep sink will drain faster and better into a 2" pipe. Use a 3" closet flange, a 4" is not needed. Toilets trapways are 2 1/8" wide. All of this is draining into an ejector pump, a clean out is probably not needed since you have access from the pit. If you do install it, again 2" pipe.

I'm not a plumber but I believe the the wye for the toilet and the connection for the shower, as shown is not allowed. The shower must connect to the 3" line after the toilet. A shown toilet waste can back up toward the shower drain and clean out. Someone else will probably confirm my suspicion.

https://www.co.lincoln.or.us/sites/..._-_helpful_hints_residential_construction.pdf

https://www.homedepot.com/p/NIBCO-2...RCH=REC-_-pipsem-_-100345781-_-100344161-_-N&

thanks for the insight...

 

[WorthFlorida]

Here is an excellent video for bathroom plumbing and it references chapters for UPC and IPC code.
Going with a 4x3" toilet drain is probably better and it does show all minimum pipe sizing. Do take a note on the 3" main trunk (crawl space in the video) and notice how everything wye's into it. For the shower connection it would be the same as the sink. In your drawing move the main truck more toward the the center of the room or on the other side of the wall. If you are adding the injector pump, do realize that it also must be vented. Read its installation manual for this requirement.

 

[Swamp Dood]

What is a "deep sink"?

Virginia uses the IPC, which restricts horizontal wet venting to bathroom groups (and they haven't amended that like NC has, per up.codes). So that would mean the lav (bath sink), the shower, and the WC. Probably not the "deep sink", depending on what that is.

So the kitchen sink and likely the deep sink need their own dry vents, as does the lav. You may be able to use the lav to wet vent both the shower and the WC, but you have to keep the bathroom group drains separate from the other drains if you want to do that. And the lav has to join the WC or the shower individually, rather than having the shower and the WC join each other, and then join the lav. The IPC doesn't require the WC to be the last fixture on the wet vent, unlike the UPC.

Cheers, Wayne

P.S. It's worth taking a look at circuit venting, that might work out better for your layout.

OK... here is my attempt at a plumbing diagram of my plan. Maybe this will be clearer on what I am doing. This is the ONLY plumbing in the whole building and is vented on both sides up and through the roof with 2" pipe.

 

[Swamp Dood]

Here is an excellent video for bathroom plumbing and it references chapters for UPC and IPC code.
Going with a 4x3" toilet drain is probably better and it does show all minimum pipe sizing. Do take a note on the 3" main trunk (crawl space in the video) and notice how everything wye's into it. For the shower connection it would be the same as the sink. In your drawing move the main truck more toward the the center of the room or on the other side of the wall. If you are adding the injector pump, do realize that it also must be vented. Read its installation manual for this requirement.

OK... here is my attempt at a plumbing diagram of my plan. Maybe this will be clearer on what I am doing. This is the ONLY plumbing in the whole building and is vented on both sides up and through the roof with 2" pipe.

 

[wwhitney]

I assume that in the lower left, for the lav and the kitchen sink, the blue line is a vent that is at least 6" above both sink flood rims, and the drains (black lines) don't actually rise above the vent.

If your layout had the lav and the deep sink swapped, that would be a classic horizontal wet venting of the bathroom group (WC, shower, lav). But as I mentioned, the deep sink (which I'm thinking of as a laundry sink) isn't allowed to participate in horizontal wet venting, as it's not a bathroom fixture.

So unfortunately you need to rearrange things a bit, there are various alternative possibilities. To use horizontal wet venting for the shower and WC, most of them involve keeping the deep sink and kitchen sink drains separate from the bathroom group drains, until a point downstream of all the bathroom group fixtures.

Cheers, Wayne

 

[Swamp Dood]

I assume that in the lower left, for the lav and the kitchen sink, the blue line is a vent that is at least 6" above both sink flood rims, and the drains (black lines) don't actually rise above the vent.

If your layout had the lav and the deep sink swapped, that would be a classic horizontal wet venting of the bathroom group (WC, shower, lav). But as I mentioned, the deep sink (which I'm thinking of as a laundry sink) isn't allowed to participate in horizontal wet venting, as it's not a bathroom fixture.

So unfortunately you need to rearrange things a bit, there are various alternative possibilities. To use horizontal wet venting for the shower and WC, most of them involve keeping the deep sink and kitchen sink drains separate from the bathroom group drains, until a point downstream of all the bathroom group fixtures.

Cheers, Wayne

thanks again...

correct assumption on lower left... bad drawing on my part. ;-)

shower wet vent should be adequate down stream then?

 

[wwhitney]

Well, you could dry vent the shower and use that to wet vent the WC. The deep sink drain would have to be kept separate from the shower/WC drain until downstream of the WC. The shower trap outlet could point towards the nearby wall at a 45 (assuming there's no convenient wall between the shower and the WC); the shower drain can run under the wall for a bit so a dry vent an be taken off, then it can join the WC drain via a horizontal wye, and then the deep sink drain could join in.

Or you could use the dry-vented lav to wet vent the shower and the WC. To do that, the deep sink would again have to run separately to downstream of the WC, as would the kitchen sink. The lav drain would run maybe up and to the right (on your floor plan picture) to get to the right side of the WC; then it could pick up the shower and the WC, or vice versa (but the WC and shower can't combine before hitting the lav); then the deep sink and kitchen sink can join in.

Or you could try circuit venting, depending on the answer to a question I posed here: https://terrylove.com/forums/index.php?threads/circuit-venting-question.91391/ You'd make the horizontal drain from the deep sink to the WC 3" all the way (a requirement of circuit venting); and you'd take off a dry vent from the horizontal drain for the circuit vent. That would definitely be OK taken off between the shower and WC (which would require running the horizontal drain under a wall like in the wet vent option), but it would be nice to take off just downstream of the deep sink joining in, so it can rise in the same wall as the deep sink vent (and join it at least 6" above deep sink). I'm just not quite sure if that second location is allowed for circuit venting, though.

Cheers, Wayne

 

[Swamp Dood]

Well, you could dry vent the shower and use that to wet vent the WC. The deep sink drain would have to be kept separate from the shower/WC drain until downstream of the WC. The shower trap outlet could point towards the nearby wall at a 45 (assuming there's no convenient wall between the shower and the WC); the shower drain can run under the wall for a bit so a dry vent an be taken off, then it can join the WC drain via a horizontal wye, and then the deep sink drain could join in.

Or you could use the dry-vented lav to wet vent the shower and the WC. To do that, the deep sink would again have to run separately to downstream of the WC, as would the kitchen sink. The lav drain would run maybe up and to the right (on your floor plan picture) to get to the right side of the WC; then it could pick up the shower and the WC, or vice versa (but the WC and shower can't combine before hitting the lav); then the deep sink and kitchen sink can join in.

Or you could try circuit venting, depending on the answer to a question I posed here: https://terrylove.com/forums/index.php?threads/circuit-venting-question.91391/ You'd make the horizontal drain from the deep sink to the WC 3" all the way (a requirement of circuit venting); and you'd take off a dry vent from the horizontal drain for the circuit vent. That would definitely be OK taken off between the shower and WC (which would require running the horizontal drain under a wall like in the wet vent option), but it would be nice to take off just downstream of the deep sink joining in, so it can rise in the same wall as the deep sink vent (and join it at least 6" above deep sink). I'm just not quite sure if that second location is allowed for circuit venting, though.

Cheers, Wayne

thanks again for all your insight...

The building is a barn/workshop so it may have different rules for separation of fixtures... I am going to assume it doesn't matter if my 'deep sink' where I clean horse poop off my shoes is okay to include on the bathroom lines. ;-). I am going to run the shower and sink in after the WC because of fixture and pipe height differences.

 

[wwhitney]

OK, if you want to treat the "deep sink" as a lav, you're good to go with your original layout.

Cheers, Wayne