What size for a toliet vent pipe thru the roof?


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Old 03-03-05, 07:37 AM
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Question What size for a toliet vent pipe thru the roof?

I am pondering adding a 1/2 bath. What minimum size vent pipe should I use to vent a first floor toliet, up thru the second floor and thru the roof in an older lath and plaster home where the studs are 24" on center?

Since the toliet drain is a 4" pipe, I wonder if I can vent it with a 2" pipe that will fit more easily between the 3 1/2 inch deep stud walls as if runs up to the roof.

Since the new drain/vent would be PVC, then will I end up with a PVC pipe thru the roof and exposed to the sun, or is there a transition piece of plumbing where it meets the roof, such that the pipe above the roof shingles is not PVC?

The 1/2 bath, if built, would be on the opposite side of the house from the existing toliet, drain and roof vents. So the new toliet and sink would need new drains and most importantly, new venting.

Actually, the cost of venting the toliet will be one major factor that may prevent the bath project from ever getting on the to-do list.

As a minor question...if the sink is positioned adjacent to the toliet, will I need to vent it separately, or will the toliet drain/vent serve as the vent for the sink?
 
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Old 03-03-05, 04:14 PM
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Saw your location.... This is all local code issues and you happen to be in an area of the country where all the different codes are used and even parts of some coding are co-mingled with other codes. It's great to live in a progressive part of the country.

Call a local code official for your project. Any answer here can be shot down for coding purposes.

Probably not what you wanted to hear...

BTW: the PVC through the roof is a real interesting question, not to mention hoar frost issues which you should also ask about.
 
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Old 03-04-05, 09:01 AM
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Drains and venting are based upon fixture loading, which is a value assigned to each fixture determined by the volumn created through use.
If it is your intent to connect to the exiting vent stack for the new bathroom then you will be required to maintain the existing vent system or to even increase it if it has been reduced.

You'll need to maintain the correct pitch for the drain and when you arrive at the closet bend for the new bath you'll need to turn it 90 degrees to verticle and hub it off for the closet bend. 4" requires less pitch than 3".

You'll need to vent each fixture, however, if you use the correct size, you can loop vent.
 
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Old 03-04-05, 09:14 AM
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Code office is the way to go. We are from all over the place including other Countries. In your area I would switch from PVC to a piece of no-hub cast iron before exiting the roof. You can use a no-hub coupling for this purpose. In the bathroom, you MAY (back to code again) be able to use an Air Admittance Valve but it does need to be vented seperately. Good luck with your project.
 
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Old 03-04-05, 10:39 AM
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Thanks all for the reply's.
I had heard of Air Admitance Valves some years back, (was labeled Quick Vent by the guy who showed me one) but did not know they were available for toliet vents.

Thanks.
 
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Old 03-04-05, 10:47 AM
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I had mentioned the AAV for the sink. I don't believe there is one for a toilet. Sorry for the confusion.
 
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Old 03-04-05, 10:59 AM
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Got cha..
 
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Old 03-04-05, 04:14 PM
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Studor has a vent that will handle the toilet. But, not legal in KC metro under actual KC MO code. Raytown, Grandview AAV approved in some cases.
Kansas side except KCKS (still under UPC 94...no kidding) is good to go on most AAV applications following manufacturesrs instructions.

Good luck with your project.
 
 

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