Things to do while re-roofing in preparation for solar module installation?

[J.P.M.]

Are there any opinions on when and if panels should be routed over existing roof vents?

I am a newbie, but would think that vents should be moved or replaced with a roof peak vent.


In Minnesota, we have snow issues. Would any heat coming up through roof vents help mitigate snow buildup?

Putting panels over roof vents is not a good idea. Also, many building codes disallow such practices.

[Solarnemo]

Putting panels over roof vents is not a good idea. Also, many building codes disallow such practices.

Can one use a roof peak vent instead of some of the more traditional box type roof vents?

Are there rules as to how close the panels can be mounted to vents and other obstructions?

[J.P.M.]

Can one use a roof peak vent instead of some of the more traditional box type roof vents?

Are there rules as to how close the panels can be mounted to vents and other obstructions?

Often depends on jurisdiction and common sense. Check local building codes - there for the looking. Among other things around (San Diego co.), vents closer than 6" from panels are disallowed, but that's visibly violated on a regular basis.

Or, for example, in CA and other places that require the 3 ft. min. dist. below ridges, ridge vents would be a possibility. Putting a panel directly over a stink vent doesn't sound too good to me, allowed or not.

[peakbagger]

I think the roof vent the poster questioned is not a stack vent for a sewer system, rather it is a vent for pulling hot air out of an attic. For those from southern climates, in the north there is a issue where snow piles up on roof and if the temperature in the attic under the roof deck is warmer than under the soffits (the overhang at the base of the roof), there can be something called ice damming where the heat in the attic melts the snow, it run down the roof and the freezes at the base of the roof where the soffits are not warmed by attic heating. The general solution is to put vents under the roof in the soffits and then mount vents near the ridge to vent warm air out of the attic. Therefore the roof deck stays the same temp and the ice dams don't form. The vents are also useful in summer conditions to vent heat out of the roof but generally the soffits vents tend to be ignored. Thus I don't see a significant issue with covering an attic ventilation vent. By the way, the heavy snow along the coast in New England is making prime conditions for ice dams and there is a major shortage of anyone willing to go up on a roof and shovel the snow off. Other folks are using hatchets to break channels through the ice dams raising heck with the underlying roofing. The ice dams cause water to leak into the drywall so drywallers will be in big demand this spring.

A general observation not solar oriented is that most builders woefully under ventilate attic spaces and forget about what happens when its snows. Ridge vents tend to work well in the summer but are useless in the winter when covered with snow. The summer time trade off for poor attic ventilation is not as obvious as ice dams but it does tend to raise the cost for cooling as the attic tends to be much hotter than the outside and many ducts are in the attic space. The pan vents installed in the roof deck have similar issues with snow cover. Gable end vents work a lot better in winter, although its important that pans are installed in the attic on the vents that are on the upwind side of the structure as despite there being a screen on the vents, snow can occasionally blow in through the screen. Dependent on if snow builds up under the panels having a few pan vents under the panels might actually be a good thing.

[Chris D]

Wow.

If the above is true you may want to consider a professional or offer to install a neighbors house first. After that you should be better at locating studs.

That was helpful. Thanks.

[SoCalsolar]

You could also

You could also buy several pieces of art and practice hanging them on studs around the house till your hit on the first try rate is 95% or better. Take pictures of the attic and have an experienced designer draw up plans or draw your own. Then use chalk lines. If you miss on the roof you will know, remove, patch, try again. If you can't tell if you missed go inside the attic and look. If you want some pictures on how this can be done look up the thread "Solar install turning out really bad - looking for some help/advice please." page 15 shows how one forum member solved the issue. Cost effective too.

[JFinch57]

Most towns require a PE to sign off on the roof that it will take the load. Be sure to get that done before you do the re-roof, that way if there are any modifications required they can be done at the same time. The PV Quickmount that you are planning on using is excellent. I used them in my last house and got something similar but a little cheaper for my present installation. The only thing that's a pain are the nails that are in the way when you slide it under the shingle. If you can do the layout ahead of time and ask the roofer to install them while they go that would be ideal. You would have to pay them additional labor as it will slow them down considerably, but speed up your solar installation immensely. I found out that tapping them upward gently to mark the location that the nails hit, then cutting a V out of the mount to go around the nail was the best bet. That way you're not removing nails that are holding your shingles. As far as missing a stud it's not a problem. The flashing is very wide, just seal the holes good with Flashmate (available at Home Depot), which you also use around the final drilled hole. Landscape versus Portrait pose different problems so that needs to be evaluated to best utilize the roof space and what can/can't be done with the mounting. You will most likely have to put bridges between the studs (from the attic) for areas that don't line up with the required spacing. If you can get your hands on a Hilti PS38 I think it will do a deep scan through the roof. I know a Hilti salesman that will lend me one for a weekend. When I get my latest installation going I'll post how that works.

[Chris D]

Thanks all!

Most towns require a PE to sign off on the roof that it will take the load. Be sure to get that done before you do the re-roof, that way if there are any modifications required they can be done at the same time. The PV Quickmount that you are planning on using is excellent. I used them in my last house and got something similar but a little cheaper for my present installation. The only thing that's a pain are the nails that are in the way when you slide it under the shingle. If you can do the layout ahead of time and ask the roofer to install them while they go that would be ideal. You would have to pay them additional labor as it will slow them down considerably, but speed up your solar installation immensely. I found out that tapping them upward gently to mark the location that the nails hit, then cutting a V out of the mount to go around the nail was the best bet. That way you're not removing nails that are holding your shingles. As far as missing a stud it's not a problem. The flashing is very wide, just seal the holes good with Flashmate (available at Home Depot), which you also use around the final drilled hole. Landscape versus Portrait pose different problems so that needs to be evaluated to best utilize the roof space and what can/can't be done with the mounting. You will most likely have to put bridges between the studs (from the attic) for areas that don't line up with the required spacing. If you can get your hands on a Hilti PS38 I think it will do a deep scan through the roof. I know a Hilti salesman that will lend me one for a weekend. When I get my latest installation going I'll post how that works.

Great advice from everyone. I pulled the trigger on the roof, and the new roof is almost complete. I'll have to work around the nails, as I didn't get a chance to work out putting the mounts in with the roofer. He's a one-man operation and pressed for time, so it probably would have been too much to ask anyway.

I've secured the services of a local electrician and solar installer to provide subject matter expertise and check my plans. I figure it's cheap insurance against really screwing up, and the permit process in the city I live in is not simple, so I feel a lot better knowing that a pro will help me navigate that. Optimistic about the outcome at the moment. I'll drop in with an update later.

Thanks again!

Chris

[J.P.M.]

Great advice from everyone. I pulled the trigger on the roof, and the new roof is almost complete. I'll have to work around the nails, as I didn't get a chance to work out putting the mounts in with the roofer. He's a one-man operation and pressed for time, so it probably would have been too much to ask anyway.

I've secured the services of a local electrician and solar installer to provide subject matter expertise and check my plans. I figure it's cheap insurance against really screwing up, and the permit process in the city I live in is not simple, so I feel a lot better knowing that a pro will help me navigate that. Optimistic about the outcome at the moment. I'll drop in with an update later.

Thanks again!

Chris

So far, so good. Respectful suggestion: Trust some (at your peril), but verify everything everyone says and does. Get it in writing and get everyone's name at the beginning of any conversation. Welcome to the world of project management. You can delegate authority, but not responsibility. Your house, money, choices, not the vendors'.