Roof penetration conflicts with solar panel install
I have been working with several solar firms in Calgary Alberta to begin design and pricing for a full install. Our roof layout is “pretty good” but the roof penetrations are causing some limitations for panel placement and optimal roof face usage. There are bathroom fans, plumbing vent stacks, and a couple of attic/roof vents. The roof vents are easily moved by a roofer I’ve made contact with. He’s been clear he won’t touch the others, as those are either “HVAC or plumbers problems”. Anyone experience this and have a path forward. Before I start getting plumbers into my attic and start paying $150/hr, what are some ideas or considerations from a homeowner perspective? Thank you
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Replies
kwoolfsm,
Any gable ends you can use instead of running them through the roof? That's fairly simple and DIY friendly. Once the plumbing vents and fan ducts are disconnected I'm sure the roofer would be happy to remove the terminations and re-shingle.
If you have access in the attic neither bath exhaust vents nor plumbing vents are hard to move.
Bath fans you definitely want going out the gable ends. Plumbing vents I'd move to the other side of the roof.
The hard part is staging it all so that you're not left with holes in your roof, and neither guy has to come out twice. Ideally they'd be there at the same time.
I am sure some here will not like this idea but have you considered running solar panels right over the top of the vents?
I have a vague recollection of reading recently that code now allows plumbing vents to be cut short under solar panels. The rationale is that the minimum height is to keep them from getting blocked by snow and the solar panel protects from that.
joenorm,
That's a good point. If the mounts are high enough, is there a downside?
I came here to post exactly this. I've read that solar panels can go right above plumbing vents and passive roof vents. I think I may have read somewhere that they are not supposed to go above active bath fan vents... but I can't recall where I read that, or the reasoning for it.
The way you can get this staged is first to have your HVAC tech move the bathroom vent to a gable end or a soffit.
Have the plumber move the vent to a non-solar panel side of the roof and leave the existing stub. They will simply cut a hole in the roof for the new vent, so you want to get the roofer out to install the boot, move the roof vents and patch the rest of the roof right after that before any rain storms.
Bring your a siding guy out to install the cap for the bathroom exhaust vent once this is all done.
In an open attic, these are all pretty standard jobs done all the time when reconfiguring the space bellow.
I know it feels like a lot of work but to me the roof with the missing panels always looks strange. Never mind the extra capacity, it is worth it to do this just to get the nice clean panel layout.
I see you mention plumbing vent stackS, plural. You can connect all those in your attic and use a single vent in most cases, if you follow the codes. You end up with a sort of mirror image of the wet side of your drain system doing this, with the small vents connecting to a larger common vent pipe above. This can really clean things up in many cases, and cut down on the total number of roof penetrations needed for plumbing vents.
I agree with the other posters about relocating the remaining vents. It's worth doing this to get a clean install of the solar panels. Akos is absolutely correct that missing panels to "go around" vents will result in a strange looking final layout. Do things correctly from the start here, since you're going to be looking at the end result for a long time.
Bill
"You can connect all those in your attic and use a single vent in most cases, if you follow the codes."
Bill, why isn't this common practice? Seems like net materials used wouldn't be much if any more for a single termination versus multiple--perhaps even less. Plus, you have a single roof penetration instead of multiple penetrations. Seems like all upside, basically no downside.
Is it just laziness? Or is there some downside that I'm missing?
The easiest way to vent something, and the way that typically uses the least total materials, is to continue a vertical drain pipe up through the roof so that it becomes a "vent". If you establish a common vent system, all the seperate vertical runs need to come back up to that horizontal main vent line, so you end up having to almost duplicate the main horizontal drain line at the bottom, which means more pipe, more fittings, and more work.
Bill
pnw,
It makes sense if the vents are in close proximity, otherwise you end up with long (almost) horizontal runs to connect them all, when the extension of the vent pipe straight through the roof would only be a couple of feet. What usually happens is you up with a hybrid approach, where several are connected together and more remote ones just go straight up.
One other disadvantage of including horizontal runs is it eliminates the possibility of cleaning blockages from above, and makes those blockages due to debris more likely.
Plumbing vent stacks can also be routed through gable end sidewalls, no? Why is the common suggestion among this group to vent the bath fan out the sidewall but not the plumbing vents? If the gable end does not have perforated soffit vents this is allowed. Ideally it would just be one combined vent as Bill already mentioned.
Matthew,
- In cold climates, horizontal runs in unconditioned attics are more likely to freeze and block.
- Horizontally oriented vent terminations are more likely to experience positive pressure in high winds. That pressure can push air through the traps.
- The the exterior walls of houses are often under positive pressure. That is more likely to move odors from the vent into the structure than roof top vents.
"The updated codes allow for diversion of 1.5 and 2 in. plumbing vents under PV systems using a system such as Solar Roof Jack. (Approved Sept 2016 in IBC and CBC IAPMO IGC 339 2016). "
https://solarroofjack.com/
$70 each.
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I faced a similar situation with some roof penetrations when installing solar panels. We worked closely with a local roofing contractor to move the vents obstructing the panel placement. It's great that the roof vents can be relocated. I'd recommend chatting with your HVAC and plumbing pros to explore possible solutions, as they might have experience with such challenges. I also got quality solar panels from https://solarsmart.ie/ . I thought you might be interested in an option.