I need to put the hole in the roof for the plumbing vent and am wondering where is the optimum and safest place to put it. The roof is a 12:12 and there are three skylights placed in a horizontal row about 1/3 the way up from the eave to the peak. I gather from reading sources that 10 lateral feet is about the min. safe distance unless I make the stack about two feet tall. I can get the ten feet but should I position it above or below or in line with the skylights? Do prevailing winds influence the choice? I`d like to keep it low on the roof but not sure if It`s wise. Suggestions?
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
Fine Homebuilding is excited to be the official media partner of the 2024 Building Science Symposium series! This event offers builders, tradesmen, architects, designers and suppliers to discuss topics ranging…
Featured Video
Builder’s Advocate: An Interview With ViewrailHighlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
always put the vent on the back side of the house. away from view from the road. Alot of people do not do this.
The recommended stack height is between 6" and 12" above the roof surface.
A two foot tall stack is not "code"/standard practice for plumbing vents.
Place the vent aboveand away from the skylights, or pipe it to a different roof plane as suggested.
.................Iron Helix
I gather from your concerns that these are opening skylights. If non-opening I would think that the stack location would not matter. Your inspection dept would be the best answer source.
Have you looked at the European stackless vent? I know it is approved for use and sale in the US but some local codes have not caught up. It is a vent that basically mounts right behind the fixture without the use of the typical stack.
SJ
Thanks for the responses. Yes, I did fail to mention they are ventilating skylights. That`s my major concern, I don`t want eaude de raw sewage in the master bedroom. And yes, It is on the back side of the house. That is a pet peeve of mine. I guess the question really is, do the prevailing winds play a major role in this or will it dissipate before it reaches the skylight? Not sure how these gasses "flow" near the roof surface. Or am I worrying about nothing?
Prevailing wind and certain atmospheric conditions could (does) cause the gas to sweep even down from the roof two stories above. On rare occasion we'll catch a whiff on the leeward side of the house.Remodeling Contractor just outside the Glass City.
Quittin' Time
Refer to P-3103.5 in the IRC
P-3103.5 Location of Vent Terminal . An open vent terminal from a drainage system shall not be located less than 4 feet directly beneath any door, openable window, or other air intake opening of the building or of an adjacent building, nor shall any such vent terminal be within 10 feet horizontally of such an opening unless it is at least 2 feet above the top of such opening.
One solution would be to install an air admittance valve
P-3102.3 Vent Termination. Every vent stack or stack vent shall extend outdoors and terminate to the open air or terminate to an air admittance valve.
I hadn`t seen the 4' requirement before, that helps. Was that from local plumbing code or other source? We don`t require inspections in our township for anything (yet) so I have no local authority to guide me on such things. They just want the denero.
Is the air admittance valve you mentioned the same as the valves for fixture venting or a special design for the whole system? I had planned to use one in the kitchen but hadn`t looked them over lately. Are they reliable and is there a web source that you know of? Many thanks, all.
The source is the 2000 International Residential Code - nationwide code for one and two family dwellings
P3114.3 - Individual vents, branch vents, circuit vents and stack vents shall be permitted to terminate with a connection to an air admittance valve.
The stack vavle conforms to a different specification that an individual or branch valve, so be sure to get the correct valve. Also, make sure to locate the valve a minimum of 4" above the horizontal drain being vented. If it is an attic, it must be a minimum of 6" above the insulation.
Most any plumbing supply will have these in stock and can guide you on their use.
You know, one thing I hear a lot since I`ve been building this house ...' Gee, I`m not sure. No one has ever asked us (the supplier) that before. I`ll have to get back to you.' And then, of course, they never do. So, I have very little faith in my local supplier. Or my local contractor. I haven`t decided whether or not I`m going to plumb this house or not yet. I know I`m capable, just not sure if I want to tackle it mostly because of time. I will check my supplier, but have little confidence that they will stock anything out of the mainstream, kind of like the big boxes. It`s good to know I have this resource available to get the straight scoop. Thanks.
Air admittance valve, also known as Studor valve can be found at this link
http://www.studor.com/
You may also buy plumbing supplies on line at
http://www.dafehr.com
Air admittance valves work OK most of the time for situations where there is no way around it. The reason I say most of the time is that they can malfunction, and boy, what a smelly situation that is! The prudent thing to do is use them on a single fixture such as a kitchen island sink or similar when a traditional vent just won't work.
As far as the IRC, I don't think all states have adopted it.Matt
In the absence of local inspections, you may have to work your way up to the State level to get a copy of the applicable plumbing code. Some states have adopted national codes completely, while others either partially or not at all, and have a completely independant State code. Here in Wisconsin, while air admittance valves are approved, you still are required to have a minimum of one vent terminal that is sized at least 3" all the way from the building sewer through the roof.
I`m still amazed that there hasn`t been action here on a state requirement (PA) for building code enforcement, but there hasn`t. We have more local government than almost any state in the union I`m told. I still want to build to code if possible, just for my own peace of mind. Thanks.
just put them rubber roof pentration on, they can settle close to six inches with no problem.
As soon as I saw the Studor name, It rang a bell. You are officially on my Christmas card list. Thank you.
One more concern. If in snow country, especially with metal roofs, snow snaps stacks clean off. Placing the vent near the ridge avoids this problem and solves the skylight/window problem.
Problem there is, this is log house with true gable ends with rafter-on-purlin support, which means, the peak will settle and the rafters will move in a radial fashion toward a union precisely at the peak, pivoting at the plate. The higher up I go with roof penetrations, the more I have to figure for settling, thereby creating a problem with weather seals at things like plumbing stacks. That`s why I want to keep it low on the roof. Also, those knee wall storage areas will make exellent plumbing, HVAC, wiring chases, as well as storage. Thanks for the input.