Bob-tx wrote:

I have been reading about everything I can find on radiant barriers,
but still have a few questions and concerns.

I am not talking new construction here, where radiant barrier can be
installed under the roof sheeting. I am talking about existing
homes, and then, primarily the spray on type.

Here is what I think I understand - -

Sprayed on radiant barrier will cut down 65 to 75 percent of the
sun's radiation, - but I really don't know how much cooler that
makes the attic.

Sprayed on radiant barrier effectiveness depends primarily on the
people who do the work. They can thin out the paint so it is much
less effective, they can spray it on to thin as well, and not get
the complete underside of the roof. Most homeowners would never
know they didn't get a good job. This is a major concern.

Dust on a radiant barrier surface decreases its effectiveness - the
more dust, the less effective. Although there generally is not a
lot of dust floating around in most attics, it can be stirred up
easily. For example, adding more insulation is a dusty procedure,
and if there is a previously installed radiant barrier, you will
decrease its effectiveness - to some varying extent.

There is a company that advertises radiant barriers for half price
(whatever that is) and free added insulation. If they spray their
cheap radiant barrier (about which I would have concern about how it
was mixed/thinned) and then add the insulation - instant dust.

This company has been advertising for months with some fantastic
deal or other and will only quote prices through an in home
salesman. I smell high pressure here.

Has anyone used this company? Has anyone used other companies to
spray a radiant barrier, and how satisfied are you?

I know I am asking a lot of questions, but I sure don't relish the
idea of getting ripped off. Thanks,

Bob-tx

Staple some mylar "space blankets" to the underside of your roof rafters
and be done with it.