Horizontal Wet Vent

[Dylan Whitehead]

Gentlemen,

Does anyone out there have a link or files on horizontal wet venting? Contractor wanting to argue about the proper way to install a wet vent. I will try to explain the situation as best as I can. Coming off the building drain they have put a 3 X 2 wye to the tub drain running about 6' to the trap, continue up the building drain about 6' more and then they installed a 3" combination wye and 45 to the water closet, then another 3' on the building drain they have a 3 X 2 combination wye and 45 to the lav. Now the building drain continues to catch the Master bath about another 8'.

I know it is sort of hard to get a good visual and I will try to get pics later, but with this set up would you consider this correct. I said that they needed to add a vent to the tub drain because for it to be "horizontal wet vent" the fixtures in the bathroom group shall connect to th wet-vented horizontal BRANCH drain. 2006 IRC P3108.1

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[Dylan Whitehead]

I guess the contractors argument is that he can use the building drain as the wet vent. Any thoughts on this. I read the code to say that the wet vent must be on the horizontal branch connecting to the building drain.

[Matt Vozzella]

The contractor may be correct in the installation but determination can't be made without knowing what the rest of the system looks like. The building drain can be a wet vent but there are reasons to not do this, the first being is that it makes it difficult or impossible to add plumbing at a later date without "breaking" the wet vent. Also under Florida code (based on IPC) when wet venting a bathroom only bathroom fixtures can be on that vented horizontal line, any other fixtures would have to connect downstream of the bathroom (or bathrooms in this case) connection.