I’d like to eliminate as many roof penetrations as possible. I got most of them under control (direct vent furnace and HW heater), but the plumbing stack is next on the list. Anyway to eliminate this damn thing?
Can I poke it out high up on a gable wall? Obvioulsy I need to get this all past the inspector, but I’d like to know what is feasible.
MERC
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Replies
I think codes require the main vent header to be terminating out the roof. I can understand trying to minimize roof penetrations, but a vent header properly installed and flashed should cause no problems. The proof is in the millions of houses which have them and haven't had a problem.
BTW, the opinions of those on the forum mean nothing if they conflict with the BI. He should be the first one you ask.
I did work on a farmhouse a while back that had its main vent header out a side wall, and whether coincidence or not, they have had a long history of plumbing problems.
Put it on the back roof.
Is this on that beuty that your working on with the killer porches?-I
ve got a thing for porches. sorry . You know I have always wondered if you jumped off a vert. pipe with a 45 and went towards a gable in the attic if they would allow you to get outside just below the peak. so I am interested in the answers to this question.
Funny thing about progress--everybody follows the old ways because " it has always been done that way" and it is great to be able to explore new ideas. I'll stay on this thread to see how it ends. Mike
Merc, if I am correct (and that's IF...), the UPC does not allow vents to terminate thru a sidewall but the IRC does. I'd call your building inspector and see what they're going with. It recently changed to IRC here.
I too, wanted to minimize my roof penetrations. But not because I doubt the effectiveness of singles and flashing when properly done (and it is pretty easy to do it right on a 12:12 roof).
But because of sliding snow considerations. Direct-vent HWH that also does RFH. Range hood goes through a side wall as does the dryer vent and HRV. But the DWV vent pipe goes up. All consolidated into a single 4" pipe (less likely to freeze closed than a 3"). And that vent pipe jogged up to high on the roof. So that sliding snow would slide away from it instead of on to it.
"The proof is in the millions of houses which have them and haven't had a problem."
The proof for it is in that a large percentage of roof failures are at boots and other assorted penetrations. I love it when a house has lots of penetrations. My old roof had two plumbing penetrations within 6' of each other. Nice hack job on that one.
So code aside - does anybody see any reason that a horizontal plumbing stack wouldn't vent as well as a vertical one?
And as another approach - I have almost 14' to my ridge from the floor on my second story. I had planned on leaving it all cathedral ceiling, but I would be willing to put a 10' ceiling over one of the rooms in a gable and I could make that attic space "outside" and terminate the vent in there (but it would still be under the main roof. Anybody think that might fly? What does the code say about that? Obviously I would to seal that attic very well from the rest of the house, but I think I'm using poly foam insulation anyway.
Like I said, just tossing some ideas around trying to get a feel for what my inspector might bring up.
MERC.
I think one of the problems that can happen is if there is a breeze aerodynamics of the flat gable could cause the air to circle back drawing sewer gas lower that the stack and even into any open windows bellow.
Two approaches come to mind on that. One is toxic air modelling but that is far too conservative. Until you get to twice the building height, conceivable some emissions could be entrained in the wake of the building. (And vent stacks suck, generally, not blow).
The other is chimney design. If you are not on the ridge of the roof, you should not be more than 1 foot below for every 5 feet horiztontally from the ridge. So a stack down low on a 12:12 might need to be pretty high. But exiting close to the ridge allows you to keep it to a minimum.
And check locally about that minimum. It can be effected by design snow depths. (an 18" stack is bad in 4 feet of snow). And some areas don't want plastic or unpainted plastic extending out the roof. Requiring a transtion to metal before exiting.David Thomas Overlooking Cook Inlet in Kenai, Alaska
Like I said, just tossing some ideas around trying to get a feel for what my inspector might bring up.
I'm pretty sure my inspectors weren't cutting any extra slack by approving my wall vents. With 2-3' of dirt on my roofs, no way did I want to consider a penetration. Plumbing works fine. Horizontal, level, you don't do. Gotta drain.
The client house I did had drains all over the house. IIRC, we had 4 wall vents. No problems.PAHS Designer/Builder- Bury it!
VaTom, you got the whole house earth sheltered? Always wanted to design one of those, but am a bit hesitant if it effects resale value.
jt8
VaTom, you got the whole house earth sheltered? Always wanted to design one of those, but am a bit hesitant if it effects resale value.
Underground is what I usually call them. Client house needed a standard mortgage. We were nervous, with no comps. Appraisal came in 50% over cost. Appraiser ignored the thermal and maintenance benefits, focusing on sq ft and details.
No idea of your motivation. You a spec house builder? In which case I'd suggest not. If you're looking for a better house, take a closer look. Here's a link to the system I use. My architecture is totally different from the drawings there. This is an excerpt from the book "Passive Annual Heat Storage" by Hait.
http://www.axwoodfarm.com/PAHS/UmbrellaHouse.html
Had a couple this summer very disappointed that I was unavailble. They settled for an envelope house. A house should keep you cool in the summer, warm in winter, have no exterior maintenance and cost nothing to operate. I'm close, and at low cost.PAHS Designer/Builder- Bury it!
If I did an earth sheltered/underground, it would be for my own use, not spec. I suspect that with a really good design, you could build the shell for 40-60% of stick-built/above-ground and then would be able to focus the savings on the interior amenities. PLUS compound the savings by reducing your utilities and wind up with a 'fairly' maint. free home.
Hmm, interesting concept. Using the dirt with extruded poly to make a big thermal flywheel. What is that, a 4" extruded layer? I like that clerestory/skylight on the second design. That can really introduce a lot of natural light. Well worth the efficiency loss.
On those open earth tubes, how do you keep mold/mildew from becoming a problem in humid climates?
I ran into this earth sheltered article a while back:http://www.mwnews.net/html/ole_s_house.html
(I did NOT hijack the thread, its VaTom fault!) ;)
jt8
On those open earth tubes, how do you keep mold/mildew from becoming a problem in humid climates?
Very good question that nobody I know has the answer. My best guess is UV treatment. We did without the tubes. Didn't get Hait's 7° annual temp swing, got 10°. Really nasty summers, up to 12°. Will not go below 65°. We're serious about dehumidification, so a week of higher temps isn't all that uncomfortable. Bearing in mind we're charging our flywheel all the while. We do a .5ACH with a heat exchanger. Found that a heat pump water heater is a great help. Our place is 20,000 cu ft in a 4166 degree-day climate.
Our umbrella has 4" xps, tapering to 2", extending 20' from the perimeter, depending on trees. We have copper sheathing on all exposed walls. Client house even got copper clad windows, which is what our next digs will get. Zero maintenance.
GC client coming up wants early Gehry (Santa Monica) design with PAHS. No problem. Can look like just about anything. He's tired of working one month/yr just to satisfy his creature comfort bill. Take a look at your utility bills. One month isn't unusual.
Thanks, I hadn't seen that link. Our place is considerably simpler. Don't tell Cloud, but I'm not partial to domes. I'll sideband you a couple of photos. They're here on BT somewhere.
(I did NOT hijack the thread, its VaTom fault!)
Ha! Glad you were interested.PAHS Designer/Builder- Bury it!
I believe its a well known fact that warm air will RISE more readily than any other direction.. maybe thats why they install furnace smoke pipe in an vertical position rather than a horizontal one.
Yeah, but as Dave pointed out, vent stacks don't usually vent they draw. so draw should be roughly the same on horizontal and vertical, particulary if I go to a 4" pipe.
MERC.
velocity of air out of a pipe is related to the velocity of air across the pipe at its opening. the draw out of a vertical pipe is greater than the draw out of a horizontal pipe since the prevailing winds blow horizontally. you would need a vertical draft blowing across the mouth of the horizontal pipe to get a draw. ever tried to light a fire in a wood stove outside with a short or no stack pipe? there's no air blowing across the outpipe, so no smoke is drawn out, despite the tendency of the hot smoke to rise.
Cool. Thanks for the info.
So this is presumably the basic principle that allows power vents to work on sidewalls, but requires passively vented appliances to have a vertical stack with limited horizontal runs and elbows.
I don't mind having the penetration out of the roof as long as nature, and not some nit-witted code, dictates it.
MERC
Stacks only draw when you are draining water which causes a suction and the water is off more that it is on. Some may argue that the main sewer is always drawing but every time I work on a pipe heading out to the main line I usually get a face full of moist methane enriched air(wonderful).
it'll work (allow the plumbing to function) just fine - - I did just what you contemplate for the same reasons - - a vent out the side wall at about 9' on the east side of the house - a few times a year I catch a whiff of sewer gas when the atmospheric conditions are just right, no big deal because of the location - I could concieve of a situation where prevailing winds could cause gas to be a chronic circumstance, so be aware..."there's enough for everyone"
Ah I think I have the solution then. How about taking my plumbing stack up to the ridge and instead of exiting the roof, I put a "T" on it and go East/West to both gables. The prevailing wind would always push air current perpendicular to that stack, which is apparently required for draw.
MERC.
Edited 9/21/2004 1:42 pm ET by DJ Merc
DJ,
Re: Vent Termination
(a) "Each vent pipe or stack shall extend through it's flashing and shall terminate vertically not less than six (6) inches above the roof nor less than one (1) foot from any vertical surface."
(b) "Each vent shall terminate not less than ten (10) feet from or at least three (3) feet above any window, door, opening, air intake or vent shaft, nor less than three (3) in any direction from any lot line; alley and street excepted."
As far as the draw/draft theories presented to you...come on...what if there is NO wind blowing across the stack or whatever? They don't work? Poppycock! And as others have said...vents do work both ways. If you are on a septic system, and your out there having a nice BBQ with friends and family, the last thing you want is to have the septic gasses overriding the aroma of those steaks on the grill!
FYI, UPC quoted is an old book. Materials are changing, but theory is still the same. But check code anyway...maybe it's different now...but I doubt it on this topic.
Peace
Okay, so code says the vent has to terminate above the roof. It doesn't say the vent has to go through the roof. How 'bout running it out through a wall, past the edge of the roof, and then go up?
Vent runs must have the same minimum slope as waste runs, so maybe this doesn't work in some situations. But if you have a gable end to the house, or a dutch-gable roof, there should be height to do it.
Speak with your inspector...IMO that would'nt look very good though.
You all can theorize all you want, but unless the inspector signs off on it all the theories in the world don't amount to a hill of beans.
NC/IRC Section P3102 paragraph P3102.1 Main vent required. Every building shall have a main vent that is either a vent stack or a stack vent. Such vent shall run undimished in size and directly as possible from the building drain through to the open air above the roof.
There is some other related stuff in that chapter. Look it up. The NC Code is on line under the NC Department of Insurance web site. Really, generally speaking, for what you are doing, you should have a copy of the code. And even still, you need to call the local plumbing inspector, or be ready to re-do it if you decide to run it out the wall. Matt
Hey Matt-
Yeah, thanks for the reply. My original post was only to see if it was possible to do. I specifically said I knew I had to deal with the inspectors, but I've gone to the mat with them before and really, they are actually quite nice to homeowners.
I wonder from the code, what is the difference between a "stack vent" and a "vent stack". I wonder if a stack vent is an air admittance valve. That would rock.
MERC
I don't know what the diff is. Still, I think the phone # for your local inspections office (Chapel hill - or is it Chatham County) should be your first resource. I'd be curious to see what they say. For all I know, that part of the IRC code is not used, and they use only the plumbing code, which I do not have access to.
Really though, I don't see why you don't want to put it through the roof. Granted, it is against logic to put a hole in a perfectly good roof, but as far as I'm concerned, far more roof leaks occur at valleys and chimneys then at vent pipes. Also, if you have the roofers do the install, it's almost fool proof.
Also, I wouldn't want to use a Studor vent (air admittance valve) for a main, and would bet money that it would not pass inspection. My expeirence with Studor vents sis that they work correctly about 99% of the time, but when they don't work correctly it really stinks ;-)
Matt
Edited 9/21/2004 10:30 pm ET by DIRISHINME
Well, Dave is wrong. Vent stacks do both, they vent out and also draw in. That is why vertical works better than horizontal.
Isn't there a cheater vent that is approved for the main stack that you can terminate it in the attic?
Approved by whom I have no idea.
greetings --I'm still hanging in there to see how this one pans out--Man there are some thinkers out there . I gave my plumber buddy a call -left a message- he'll get back to me- He always does -- Not that he knows it all but it will be interseting to get his perspective. See ya Mike
I'm with you on wanting to avoid roof penetrations. But if you live in an area with cold winters, make sure you don't have ANY cold, horizontal sections of pipe in your vent stack run. Air in the stack is warm and moist, and when it flows through the cold section of pipe it will condense. In a vertical pipe run, chances are that most of the condensate will run back down the vent, but in a horizontal pipe run outdoors there's much more risk of the condensate pooling and freezing. That might lead to a plugged vent in the dead of winter, and pressure balance problems in your drains as a result. And what the other guys said about doing it to code- if an inspector's involved, code is king. In my planned addition, the only hole in the roof is for the vent stack.
Make sure you put a screened weather cap on it too. Our neighbour had a big RotoRooter bill after a squirrel got it in his little rat brain that it was a good idea to stuff his walnuts down their uncovered vent stack. Dunno if he liked the sound, or seriously thought about climbing down there in the spring to get them back...
What is feasible.
Every group or within five feet needs a vent. The main stack vent for the system must penetrate through the roof . All other vents can join the stack vent in the attic . Main stack vent can be as much as a 45 degree angle to gain access to back of house roof. Thats as far as we as we gan go.
Tim Mooney
Tim - does your state use the IRC? Or is there a seperate plumbing code, or what? Many times the code book can be sumerized by someone "in the know" as you did above, and things become so much clearer..Matt
Arkansas State Plumbing Code
Other codes could certainly vary. Normally its up to the AHJ as he or she can go to the extreme or if they have a city ordinance ,or it can be greater but not less than.
A decision made by the inspector on a judgement call will stand as long as it doesnt misrepresent the codes intention . Sometimes decisions are made on his or her interpatation which can vary. [kinda like the bible, hence the different religions] He may have room to move on this call even if if the meaning is different to satisfy the homeowner, but its strickly their call. The book is written in black and white , but normally jobs arent done in the same manner. Decisions are rendered therefore on judgement of good faith and common sense a lot of times.
Im not really a fan of venting into the stack vent . I would rather see each "group", vented through the roof. The reason is simple to me since I have rentals , that I can run all the vents if I want to and extend through the main line catching "all" main drains. If you talk to a plumber that does the work , he wants to vent to the stack vent. It saves him time and material. If you talk to a Rotor Rooter guy , he will tell you that he will use those vents to clear drains not accessable by wall or ground cleanouts. I will tell you as a lanlord that a homeowner can tape easily through vents but may not have the ability to put a tape through all the turns going through an out side cleanout. A homeowner will say that they do not want to see the pipes sticking through the roof. By no means do they want them on the front of the house, or easily seen from the street. Our State Inspectors say its ok to work a little with homeowners on that issue unless it serves a threat to public saftey such as a gas vent .
Depends on which side of the football you are on when its snapped, as how you might look at it .
Tim Mooney