Plumbing stack vent - code and practicality of re-routing above the roof but under a solar array?
Question:Please respond ONLY if you have some professional expertise on the subject of building codes and plumbing. I install solar electric systems. Installing solar arrays around plumbing stacks on roofs can sometimes be problematic. What are the code requirements and practical issues around re-routing these vents in the 2" to 4" gap between the shingles and the underside of the solar modules? Can I cut the stack short, put a 90 degree elbow on it and run in off to the side? Can I obtain other angled elbows and run it up the roof? I understand that I want to avoid having the vent get blocked by snow or ice.
Answers:
The vent cannot be reduced from it's present size nor can a trap be formed that can hold water. Aside from that a vent can be turned as often as you wish and directed all the way to the ridge if necessary. A vent consists of 2 zones. The wet zone, which is the portion of vent from six inches above the highest drain in the structure all the way down, and the dry vent, which is everything above that point. In the dry vent part, only air and gas flows so direction is not an issue. The easiest way to move the vent would be through the attic. I would follow the roof line as much as possible. When you use a hole saw to cut the new hole, save the plug. Fasten it to a larger board and attach this to the old hole from the inside then re shingle that section. Buy a new boot for the stack, it will save any possible leaks from the old one. I would not recommend cutting the stack short and turning it on the roof as you may have a problem flashing around it and it could be a spot for water to get into the house not to mention the hassle they roofer will have when it needs to be re roofed.
the best thing to do is run it up the roof. but once you get away from the panel be sure and turn it back vertical and up at least 12". if you leave it on its side animals will nest and block it
not just ice, but the decreased clearance will attract nest building animals...
I've seen homes with no roof penetrations & automatic vents just above the top plate, i wouldn't suggest that, but maybe for 1 or 2 in a specific area to allow installation, & if they were accessable to change when they failed!
Under UPC code, the vent has to extend through the decking of the roof 6".
The is no reason why you cannot offset the vent under your panel, but 4" is a tight area.
Can't you raise your panel?
rangedog is correct. the upc and ipc codes both only call for a minimum of 6" above roof termination. there is a need for roof flashings. these are installed by the roofers and must be used to ensure the roof does not leak. they are usually about 8" wide and twelve inches long. you also need 12" clearance from roof peaks. all rerouting should be done in an attic space.
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