Foil backed OSB for Roofing

Just wanting some advice on if it is worth the extra cost to use foil backed OSB for roofing? This is supposed to save on energy bills, but I was trying to see if anyone has any advice?
I have also seen folks using regular OSB and stapling foil to the underside of the OSB - not sure if this is cheaper, but I assume it is. Anyone using this method?
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I stapled foil loosly to the underside of my roof decking on the shop. Dropped my temp 25 degrees right now. I'm in west Florida. Seems to work real fine considering the low cost.
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Raider Bill wrote:

plan on spraying foam insulation on the underside of the roof sheathing. Will this defeat the purpose of the foil? I think I read it might, but can't find it now.
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Hambone wrote:

I remember reading that the foil works best if there is an air space between the foil and the next material in the direction of the reflection. Putting insulation directly on the foil would in theory reduce the effectiveness. My memory may be incorrect however.
--
Carolyn Marenger


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I think it would be the cats meow. I live in central Iowa, and this past summer I couldn't even get it shipped here. I would of had to purchase it in Arkansas I believe, and had it shipped up...way outta line. So if you can get it...I'd go for it. I've seen some use the foil laid on the trusses before the sheating went on...but I can imagine it would be a PITA task to hold the foil down keeping an air space on each truss. One source of the film is Farmtek.com.
The spray foam insulation on the bottom of the sheating might not be a good idea. You might want to check to make sure it won't void the shingle warranty. I just looked on the Owens corning site and there wasn't a specific reference to that, but a the local installers won't touch it. Others say that the foam keeps the roof deck too hot, and it will cause premature shingle failure.
DAC
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Thanks DAC - for the roof where I might spray the foam on the underside of the roof - this is a flat roof - actually a 1/12 pitch. So it won't have traditional shingles...more than likely will be a solid rubber/moleskin type covering. But I will check with my roofer before I have it sprayed to be sure.
DAC wrote:

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Sorry I should'a asked...flat roofs here = leaks...so we don't see many, and I didn't even think about it. I am glad you're going to check first...better safe than sorry!
DAC
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No real roofers where you live ? Sorry
kickstart
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