On Jun 15, 4:14*pm, "Bob-tx" wrote:
I have been reading about everything I can find on radiant barriers,
but still have a few questions and concerns.

If the laws of physics apply here, radiation impinging on the roof
will heat up the roof and sheathing as it passes through into the
attic. There it is met by the 'barrier, which is simply an aluminum
(paint or whatever) reflective surface. So it passes through the
sheathing and shingles a second time on its way out, thoroughly
cooking those materials. Soffit and ridge vents are installed to
permit air heated by such radiation to be escorted out the peak of the
roof. Maybe I missed something here, but it seems to me the net effect
would be to shorten the life span of the roofing quite a bit. Seems
more logical to get the radiation reflected away before penetrating
the shingles and sheathing, like using bright white shingles in the
first place, or painting the roof roof with aluminum paint, something
not very stylish in today's McMansions.
Over all, the proposed 'radiant barrier' might be like duct cleaning,
high priced and marginal unprovable benefits. Whatever, good luck.

Joe