Things to watch out for during solar install?

[peakbagger]

Most contractors who have been in the trades long term hate OSB. It is usually much cheaper than plywood and meets the codes but it tends to deteriorate over the long term. It also telegraphs wide rafter spacing far more than regular plywood. I don't know of any contractor that will let it near their own home. Yes its legal but I expect at some point folks will regret using it.

[sensij]

You guys made me consider a ground mount instead. New thread here: http://www.solarpaneltalk.com/showth...unt-vs-rooftop

What in the conversation above would make ground mount seem like a good idea? My roof was 50 yrs old, with a 2nd layer of shingles put on after 25. I had it re-roofed before my solar install, and only two pieces of sheathing needed replacement.

The shade of the panels will help extend your roof's life, as long as the install is done well.

[gvl]

What in the conversation above would make ground mount seem like a good idea? My roof was 50 yrs old, with a 2nd layer of single put on after 25. I had it re-roofed before my solar install, and only two pieces of sheathing needed replacement.

The shade of the panels will help extend your roof's life, as long as the install is done well.

It's just an idea, not necessarily a good one. As I mentioned in the other thread not needing to replace the roof now and 2kW fewer panels is a $11,000 difference sans the tax credit. Ground mount has its benefits such as cooler running panels and easier access for maintenance or repairs (to both the panels and the roof), not to mention 1 ton of equipment on the roof isn't going to improve the stability of the structure during an earthquake. Just want to better understand the costs involved and potential problems.

[inetdog]

Most contractors who have been in the trades long term hate OSB. It is usually much cheaper than plywood and meets the codes but it tends to deteriorate over the long term. It also telegraphs wide rafter spacing far more than regular plywood. I don't know of any contractor that will let it near their own home. Yes its legal but I expect at some point folks will regret using it.

OSB can probably fit in better when used for wall sheathing rather than roof sheathing. That is a much less hostile environment and has less mechanical loading than OSB spanning rafters and support the weight of roofing materials and people walking.

But I do not think that OSB in wall sheathing meets the requirements for a shear wall in earthquake country. You need to use conventional plywood for that.

[dusty144]

This is getting OT but...
There is nothing wrong in using OSB per se. It is a much more efficient product and you get a lot more panels out of even poor quality wood, it is cheaper and needs fewer and lower quality trees and you can make 12’ panels with it. It is very much used as a shear wall all over the country as well, as part of a system. That said it does have problems as noted with 24” O.C. rafters. For that matter even Struc Plywood has trouble w/ 24” O.C. rafters which seems to be the norm these days with the cheaper builders. My house, built in the 1950’s, has 12” o.c. Rafters! OSB does tend have a shorter life span, typically 20-30 years depending on the climate, monitoring, attic design, etc. mostly due to the way the panels react to humidity/moisture.
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The OP is in an unfortunate borderline situation.
20-35 year old roof and most likely everyone would advise replacement prior to installing PV.
5-10 year old roof and most would likely say there should be no problems, go ahead.
Tough choice this.

[gvl]

The roofer's opinion on the roof I should be able to get at least 15 years from it, he said he wouldn't replace it now for solar. I guess I'll be taking my chances.

[gvl]

Is this footing/flashing installed correctly? Something is not right here, or is it just me? This is presumably an example of workmanship of the installer I'm starting to work with.



I always thought the flashing should go above the lower shingle, not through and under it.

[sensij]

Ideally, the cutout would not have extended through the entire shingle and into the next row. I think it works best if you stay below the nail holes of the shingle that is being cut, but I have no expertise in this so I'm not certain. If you look closely, I think that condition is met.

[J.P.M.]

Usually the flashing will go under the "uphill" shingle/tile, and over the downhill shingle/tile.

[gvl]

Usually the flashing will go under the "uphill" shingle/tile, and over the downhill shingle/tile.

Would there be any reason not to go over the downhill sshingle and instead cut through it like it's done here?

[sensij]

The bottom of the flashing is in fact over the bottom shingle, in the next row. Just not as much overlap as you sometimes see.

[J.P.M.]

Would there be any reason not to go over the downhill sshingle and instead cut through it like it's done here?

I'm not a roofer, but if I had my druthers, which I did on my job, I'd have the roofer double flash all the penetrations. In your upper photo, it seems that the flashing could have just as well have covered (been "over" or "hiding") the shingles on either side at the level of the penetration. The lower photo looks like quick mount and seems a better method than the top photo, although (editorial) I'd prefer to see an aluminum collar around the post above the rubber collar for added protection for the rubber.

[foo1bar]

Would there be any reason not to go over the downhill shingle and instead cut through it like it's done here?

In the first photo with the square cut out of the shingle, it looks installed correctly to me.
The downhill edge of the flashing is directly on the shingle below.
If the bolt were in the same location but the flashing was one shingle course up, the downhill edge would be not on top of a shingle. And that would not be correctly installed at least for my flashing. My flashing was a different brand - but I'm guessing it'd be the same instructions.

Looking at it, I would guess there's plenty of flashing above the penetration going under the shingles above - really that's the question - is there enough overlap. And I would think there is. (Assuming it's not been so as to avoid nails.)

The round cutout one looks great IMO - the flashing is right at the edge of the shingle - not overhanging, and minimizing the cutout of the courses above.

[gvl]

I suppose my only concern here is that at least some amount of water may enter to the left/right of the flashing under the shingle that was cut and further potentially getting through the nailing holes.

The 2nd photo is what I think is a proper installation, I included it just as an example of such.

[J.P.M.]

I suppose my only concern here is that at least some amount of water may enter to the left/right of the flashing under the shingle that was cut and further potentially getting through the nailing holes.

As to one of my comments in post 42 of this thread.