Plumbing vent lines

Originally Posted By: jhorton
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I have a house that has one 4" vent line for the whole house. That inclued 3 toilets, shower, 2 tubs, washer, 4+ sinks ect. Is this adequate? I have never seen a house with only one vent line for the whole house.


And it's actually 2 - 2" lines tied togeher into a 4" line. Oh, let me put up a photo. This is the strangest thing I have seen in a while.

![](upload://5gsIByFtqV6oD141NpXPduqEUNZ.jpeg)

This vent is for the (as far as I can tell) the whole house. I was always under the impression that you needed at least one 4" vent per bathroom. But I am not a plumber either.


--
Jeff <*\\><
The man who tells the truth doesn't have to remember what he said.

Originally Posted By: bking
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house has none of those under sink air valves anywhere?


I'm not sure of the minimum, but it sure would seem wrong based on other houses


Originally Posted By: jhorton
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No other vents that I can find. If they are there they are well hidden. I have nothing to base this on other that what is typical in our maket. Woudl prefer to have something more that says this is wrong… Or acceptable for that matter!



Jeff <*\><


The man who tells the truth doesn’t have to remember what he said.

Originally Posted By: Tom Bijak
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Although I’m not a plumber, I’ve seen plenty of vent configurations and in general, either two 2" or one 4" is not enough for number of fixtures listed:


Each 2" vent pipe can handle 4 DFUs and 4" can handle 8 DFUs. Given Tubs are 2 DFUs each, Sinks 1 DFU, Showers 2 DFUs, and Clothes Washer 2 DFUs, if these are only vents they are substandard.

I have to believe there is either a Waste Stack handling part of the Venting load-- which is allowed-- or other Vents.

Keep looking.


Originally Posted By: ckratzer
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Minimum 1 vent to exterior 2003 IRC [3114.7]


That 1 vent should be 4" and of course the 2" vents should tie into it.


I recently had a spec.home inspected by the city codes admin. and this plumbing situation passed with no question.


The mentality behind it is that it is adequate and the fewer holes in a roof the better.