Myths/Partial truths and facts.
Fact : The absolute best spray on the market not watered down, applied at the exact thickness specs (rafters and decking covered) blocks 75% of radiant heat (and this has been tested on a smooth non porous surface) there are no real test numbers that show how it performs on osb decking ie: your roof decking. True numbers on how much heat it blocks are 10-75%
Myth: Foil blocks cell phone signals, there are no studies that show this is an issue and I have never had a complaint regarding reception. (no problems in my house either, I actually get better reception)
Partial truth: Dust accumulation on the foil diminishes its effectiveness, this use to be true, a decade or so ago there was a foil on the market that was single sided (foil on one side, a kraft paper of sorts on the other, because it only worked on reflecting heat it would start losing effectiveness as dust accumulated. The latest foil (ours) is double sided. A double sided foil works with reflectivity as well as emmisivity, long story short...even if the foil did collect 2" of dust or more on the surface it will not allow more than .03% of radiant heat to pass through. This is why a double sided foil is guaranteed to block 97% of radiant heat.
Myth: Foil will increase shingle temperature more than spray,
absolutely false, foil will increase shingle temperature by 2 degrees (as a longtime roofer I can testify that this is nowhere near significant) I do not have numbers on the spray barrier however being that it is applied to the decking directly I would only have to assume that it creates conductive heat by contact and has a greater temperature effect.
And lastly a very misleading advertising ploy by spray on companies...Spray is NOT energystar rated, it does not qualify as a true radiant barrier by definition and does NOT qualify for tax credits on it's own (this is why they give you a little blown in insulation and upsell you on even more even if you don't need it) Foil is Energystar rated and qualifies for the tax credits (we provide that paperwork upon completion)
Pirate Roofing & Radiant Barrier - Lifetime warranty on labor and material. Honestly, the true savings on your energy bills in the summer on average are usually 25-30%, the most I have seen on one of our jobs was 52% (unusual but true)
We only use a 5mill, double sided 99% aluminum, perforated foil (you can't get a better foil...period) You cannot tear it, pull it apart etc, you can walk on it, store items on it etc.
I hope this gives insight to any questions you may have, thank you for visiting our website and please feel free to call with any questions you may have. -Jon Szilva