Best Easiest way to vent my Pre-plumbed basement set up


Old 02-10-12, 03:59 PM
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Best Easiest way to vent my Pre-plumbed basement set up

The tub/shower drain is on the right with a 1 1/2" vent stack. There is a 2" drain/vent from my 1st floor kitchen sink. There is a 4" waste drain for a toilet with a 3" vent stack behind it. I will have a sink to the left of the toilet in a 10'x5' bathroom. Can I connect all shower, toilet vents and my sink drain to the 2" drain/vent from my kitchen sink or will I need to run an entirely new vent for this group to the roof. Would an air admittance valve (They are allowed in my county and state) be an easier way to go?

Old 02-10-12, 10:45 PM
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Check local codes. But where I am there is no length restriction on a wet vent, and 2" is the appropriate size, so yes you can. I would not reccommend an air admittance valve used to vent a toilet
Old 02-11-12, 08:39 AM
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You cannot tie into that 2" sink line unless you tie in the vents 3ft above the kitchen sink flood plane on that vent upstairs.

You cannot wet vent.

The way your piping shows is that 3" stack and the 1 1/2 vent need to go up though the roof or tie into an attic vent.

Whats disturbing is that 3" vent probably was/is not needed and I am wondering why its like that or the plumber did it that way. That 1 1/2 vent could have easily been 2", as it should have been but should have been stubed up as the sink drain.

Regardless it is what it is.

Do you have a diagram of how this is all hooked togther under the slab????

I would, and thats if how I think its piped, is to cut in a tee in that 3" vent stack and run the sink into there. Then tie the sink vent and that 1 1/2 vent back into that 3" stack 3 ft above the flood plane of that bathroom sink. Then reduce that 3" stack to 2" and run up and out into the attic. And tie into the homes main vent stach up there.

Is there any pipes in the ceiling of that bath group that shows a plumber already ran the vent? You should see a 2" terminated line somewhere up in the ceiling.

Check your local code if AAV's are allowed. I dont use them myself unless absolutly neccesary. I feel if the piping is there pipe the vents accordingly.

Mike NJ

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