Plumbing vent height - InspectionNews

John Stephenson · #1 (**permalink**) 05-15-2007, 06:25 PM

............

Rick Cantrell · #2 (**permalink**) 05-15-2007, 06:32 PM

Other that being a bird perch I don't think the height is a problem.
It is to close to the valley.

Jerry Peck · #3 (**permalink**) 05-15-2007, 08:52 PM

No, on roofs used for other than weather protection only, the vents are required to be 7 feet high above the roof.

Rick Hurst · #4 (**permalink**) 05-15-2007, 10:25 PM

7 feet?

Richard Rushing · #5 (**permalink**) 05-16-2007, 04:40 AM

I think he forgot the 'smiley' after the bird-perch comment...

David Banks · #6 (**permalink**) 05-16-2007, 04:54 AM

The plumbing code here in MA says minimum of 18 inches. Max 24 inches. So I do not think your height is an issue.
Jerry 7 feet? Are you thinking of something else?

Jerry Peck · #7 (**permalink**) 05-16-2007, 05:53 AM

From the IRC (and other plumbing codes).
- P3103.1 Roof extension. Open vent pipes that extend through a roof shall be terminated at least 6 inches (152 mm) above the roof or 6 inches (152 mm) above the anticipated snow accumulation, whichever is greater, except that where a roof is to be used for any purpose other than weather protection, the vent extension shall be run at least 7 feet (2134 mm)above the roof.

That means that when there is mechanical equipment on the roof, sun decks, you name it, the plumbing vents need to extend up above the roof 7 feet. This is to get the terminal end above the peoples who will be using the roof for whatever reasons they are using the roof.

IF the roof is used for "weather protection" only (not counting when someone goes up to do repairs or cleaning on the roof - the roof's purpose in those cases is still "weather protection") then the vent terminal must be at least 6" high above the roof, plus whatever additional height is required by the AHJ for snowloading so the vent is never buried in snow.

Thom Walker · #8 (**permalink**) 05-16-2007, 08:57 AM

Quote:

Originally Posted by Jerry Peck

From the IRC (and other plumbing codes).
- P3103.1 .......IF the roof is used for "weather protection" only (not counting when someone goes up to do repairs or cleaning on the roof - the roof's purpose in those cases is still "weather protection") then the vent terminal must be at least 6" high above the roof, plus whatever additional height is required by the AHJ for snowloading so the vent is never buried in snow.

Being a clutz, I wish that they hadn't made that exception.

Jerry McCarthy · #9 (**permalink**) 05-16-2007, 11:51 AM

Does this help?

Tim Moreira · #10 (**permalink**) 05-16-2007, 12:20 PM

Quote:

Originally Posted by John Stephenson

What problems are caused with a vent being this high?

None...

Mike Schulz · #11 (**permalink**) 05-16-2007, 12:38 PM

There is nothing wrong with that vent...........Your problem lies elsewhere.

Bob Stark · #12 (**permalink**) 05-16-2007, 01:41 PM

Well said, Jeff !

David Banks · #13 (**permalink**) 05-16-2007, 02:25 PM

Quote:

Originally Posted by John Stephenson

What problems are caused with a vent being this high?

John no one said 22 inches was wrong. But the reason in MA for 24 inch max is that in cold climates condensation can occur in tall vents and freeze therefor potentially closing the plumbing vent.

Thom Walker · #14 (**permalink**) 05-16-2007, 03:02 PM

Quote:

Originally Posted by Jeff Eastman

John,

"What Mike is eluding to, but being deliberately evasive for whatever reason, is that the base flashing skirt can not extend into the valley, can cause water intrusion."

I don't agree with that. I read Mike's response as "the problem of the slow drain rate has an origin other than the vent height".

"You can have a vent that height, HOWEVER, it may also indicate previous plumbing repairs for bad venting or drainage which I think is what you were driving at in your origional question that no one answered for you. Tell your client to consult with homeowner if there were any previous repairs. Did you see any problems with the drainage to tubs, sinks in that area?"

What am I missing? All three questions were answered.

I sure wish people would just answer questions directly, state why things are or are not a problem, and then just provide the proper recommendation. It would stop a lot of nonsense on this board

Exchanges of ideas and interpretations of codes, manufacturer instructions, and generally accepted building practices is the PURPOSE of this board. This is not intended (at least I hope not) as a teacher/pupil format. It's one of those things where you have to cut through the pontificating and grandstanding sometimes, but it's a small price for the knowledge gained over time. Learning is a process, not a destination and sometimes you have to dig through the doo-doo to get to the pony.

Jerry Peck · #15 (**permalink**) 05-16-2007, 03:43 PM

Jerry M.,

That drawing is for gas vents, this tread is regarding plumbing vents.

Jerry Peck · #16 (**permalink**) 05-16-2007, 03:45 PM

Quote:

Originally Posted by Jeff Eastman

I sure wish people would just answer questions directly, state why things are or are not a problem, and then just provide the proper recommendation. It would stop a lot of nonsense on this board

They have been.

There are THREE (count them - 3) questions in that post, different people answered different questions. Nothing wrong with that.

Mike Schulz · #17 (**permalink**) 05-16-2007, 04:42 PM

Sorry I was in a hurry and shot a quick reply.

(This vent was 22 inches high. Tub had slow drainage.)
It could be a number of things but the height is not one of them such as blockage, undersized, a big hair ball in the tub drain

(What are all the ramifications of having a vent this high?)
As long as it's in the specified range as listed in some of the post, "none"

(Could a vent this high impact the drainage of the tub?)
Jerry or one of the other guru's probably answer this better but I don't think height is a question as far as drainage is concerned.

(Also, would anyone say it is a problem with the base flashing for the vent over hanging the valley?)
It would be nice for it to be further out of the valley so it don't collect debris and ice damming and large volumes of water but as long as it's installed correctly it shouldn't leak. Granted this may be the first area that may start leaking when the roof ages.

Jeff, Please forgive for I have sinned and it won't happen again

Not!

Frank Kunselman · #18 (**permalink**) 05-23-2007, 12:44 PM

John,

Food for thought. The vent height is of no relevance to the drainability of the tub. As long as the vent diameter is at least 1/2 the diameter of the tub drain and not less than 1 1/4 inch diameter the vent can run 40 feet high...if you want it to stick 50 feet above the roof deck simply increase it to 1 1/2 inch diameter (one pipe size increase).

A plugged vent could have some effect, but I would venture to guess a hairball downstream...they sure cause my tubs to drain slowly. Also, if the slope is too shallow, there is a loss of velocity which affects the rate of flow.

Back to the plugged vent theory, slow drainage would be the least of the problems. Your trap would be sucked dry which would allow sewer gas to enter the bathroom (and you were blaming the smell on the kids, right).

Some things you might want to investigate would be the distance from the trap wier to the vent, is the vent vertical off the drain or is it a horizontal dry vent. If it is correctly vented, you could always replumb the tub with 2" from the trap to the branch drain (leaving the 1 1/2" trap) or replumb with a greater slope.

I hope this helps.