Bathroom remodel - separate shower/tub
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wwhitney
In the Trades
Your challenge is venting. Each fixture needs a vet which is either a dry vent taken off vertically before the the fixture drain joins any other drain, or is a wet vent, which in this context is where the fixture drain joins another drain (typically horizontally) which is carrying only bathroom fixtures, one of which is dry vented, and that drain/wet vent is oversized to perform both functions.
So in particular, no dry vents can be horizontal under the floor; a dry vent can only turn horizontal once it has risen to 6" above the flood rim level of any fixture it is venting.
Based on that, you have several issue in your diagram. And to know what you can do in this bathroom, you need to know at least a little more what is happening in the other bathroom. If you have a 3" drain coming in from that bathroom, it would be enough to know that that 3" drain is only carrying fixtures from that bathroom, and that one of those fixtures (typically the lav) is properly dry vented.
[If there's actually a vertical vent where you show just outside the bathroom, connected to the 3" horizontal drain, that would make sense if that drain is just carrying the WC, and that would serve as vent for that WC, and under the WC you could use that 3" drain to wet vent fixtures in this bathroom.]
Cheers, Wayne
So in particular, no dry vents can be horizontal under the floor; a dry vent can only turn horizontal once it has risen to 6" above the flood rim level of any fixture it is venting.
Based on that, you have several issue in your diagram. And to know what you can do in this bathroom, you need to know at least a little more what is happening in the other bathroom. If you have a 3" drain coming in from that bathroom, it would be enough to know that that 3" drain is only carrying fixtures from that bathroom, and that one of those fixtures (typically the lav) is properly dry vented.
[If there's actually a vertical vent where you show just outside the bathroom, connected to the 3" horizontal drain, that would make sense if that drain is just carrying the WC, and that would serve as vent for that WC, and under the WC you could use that 3" drain to wet vent fixtures in this bathroom.]
Cheers, Wayne
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Hi Wayne, thanks for the response.
Does the left side of the "new" drawing look ok? The portion with the bathtub and toilet. I've sized up the pipe between the tub and toilet to 2" to serve as a wet vent for the new toilet location. Does that part run afoul of any guidelines?
Then for the right side, where i'm removing the toilet - i have confirmed that there is a vent in that wall connected to the 3" horizontal pipe. I also confirmed that the toilet in the adjacent bathroom is using that same horizontal 3" drain. I'm not able to determine 100% if this is connected to the lav, but everything drains well in that bathroom so I kind of assume it's properly dry vented. (there are no studor vents or anything under there). All that being said, on that side i'm simply replacing the toilet drain with the shower drain.
Does the left side of the "new" drawing look ok? The portion with the bathtub and toilet. I've sized up the pipe between the tub and toilet to 2" to serve as a wet vent for the new toilet location. Does that part run afoul of any guidelines?
Then for the right side, where i'm removing the toilet - i have confirmed that there is a vent in that wall connected to the 3" horizontal pipe. I also confirmed that the toilet in the adjacent bathroom is using that same horizontal 3" drain. I'm not able to determine 100% if this is connected to the lav, but everything drains well in that bathroom so I kind of assume it's properly dry vented. (there are no studor vents or anything under there). All that being said, on that side i'm simply replacing the toilet drain with the shower drain.
wwhitney
In the Trades
No, you have a horizontal dry vent under the floor, which is not allowed as I explained.
You could do the following: start the tub drain off to the left, parallel to the joist. When under the wall, hit a LT90 to go through the joist. Then a 2x1-1/2x1-1/2 combo for the vent takeoff (a tub is 2 DFU, so the wet vent needs to be 2") straight up into the wall. Then from there the 2" wet vent joins the WC drain, and then the combined drain joins your existing 3" somewhere appropriate.
I agree that if the old WC was properly wet vented, and you connect a shower there as shown, it would be properly wet vented.
Cheers, Wayne
Wayne - thanks for the write up. I understand how that vent would have to work now.
As I was looking at this I considered another option. Don't touch the left side tub drain at all. Instead, do two wyes off of the horizontal 3" run (see attached picture). I'd have to go through two 10" joists but I can reinforce them. I'm curious what you think of this setup?
As I was looking at this I considered another option. Don't touch the left side tub drain at all. Instead, do two wyes off of the horizontal 3" run (see attached picture). I'd have to go through two 10" joists but I can reinforce them. I'm curious what you think of this setup?
wwhitney
In the Trades
In your lastest rendering, the vent takeoff on the tub trap arm needs to be rolled up at least 45 degrees above horizontal, and should be a combo. [Or it is sometimes done with a a wye rolled up 45 degrees and a 60 degree bend to turn vertical.] But perhaps that is just an inaccuracy of your rendering.
So I'm going to assume the light grey pipes are the only new work. That works, but if you want to avoid drilling those joists, you could put a san-tee or combo (barrel vertical) directly below the closet flange, with the side inlet pointed towards the wall. Then the tub trap arm can hit a LT90 after the vent takeoff, and enter directly into the san-tee or combo. Then below the joists, a LT90 to get under the joists to the vertical drain.
Cheers, Wayne
So I'm going to assume the light grey pipes are the only new work. That works, but if you want to avoid drilling those joists, you could put a san-tee or combo (barrel vertical) directly below the closet flange, with the side inlet pointed towards the wall. Then the tub trap arm can hit a LT90 after the vent takeoff, and enter directly into the san-tee or combo. Then below the joists, a LT90 to get under the joists to the vertical drain.
Cheers, Wayne
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