Hi, my question here is about wet venting a bathroom, and I’ve been back and forth with my plumber friend about this. I’m told every fixture needs its own vent on its own branch. However, I’ll I see online is wet venting off the lav, toilet last, is common. In my case lav is separate so why not wet vent WC from tub dry vent as pictured. Red circle is a 2” vent going straight up between tub and WC. I’m running into this same situation in other baths that can easily share without drilling the heck out of TJI joists, thanks
Wet venting bathroom fixtures
- Thread starter Kohala
- Start date
You cant “wet vent WC from tub dry vent” because its not a wet vent. You can wet vent bathroom groups only (any combination of wc, tub/shower, lavatory, floor drain) the lavatory serves as the vent for the entire group. You are allowed one fixture above your vent. If you dont want to drill engineered joists, you can individually vent each fixture (like the tub currently)
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wwhitney
In the Trades
In re the OP, a dry vented tub drain can be used to wet vent a WC, see UPC 908.2.1 [In reading that section, the second sentence should be read as an alternative to the first sentence.] The tub drain (after the vent connection) and dry vent need to be 2" for the UPC.
In re the last picture, that fitting between the joists where the drain from the left (the lav) joins the drain from the right (the tub), is it a combo? A san-tee would be more typical.
The configuration shown is still UPC compliant as long (a) the horizontal pipe run from the trap outlet to the near edge of the vertical 2" lav drain coming out of the LT90 is at most 42" for a 1-1/2" tub trap or 60" for a 2" tub trap and (b) the vertical distance from the top of the "crotch" of the combo to the top of the trap outlet is at most one trap diameter (1-1/2" or 2").
Using a san-tee instead of a combo helps with (b) because the drop from the top of the side inlet to the top of the "crotch" is less for a san-tee than for a combo.
Cheers, Wayne
In re the last picture, that fitting between the joists where the drain from the left (the lav) joins the drain from the right (the tub), is it a combo? A san-tee would be more typical.
The configuration shown is still UPC compliant as long (a) the horizontal pipe run from the trap outlet to the near edge of the vertical 2" lav drain coming out of the LT90 is at most 42" for a 1-1/2" tub trap or 60" for a 2" tub trap and (b) the vertical distance from the top of the "crotch" of the combo to the top of the trap outlet is at most one trap diameter (1-1/2" or 2").
Using a san-tee instead of a combo helps with (b) because the drop from the top of the side inlet to the top of the "crotch" is less for a san-tee than for a combo.
Cheers, Wayne
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