1838Re: Radiant Heat Shield
- Feb 6, 2003Chris, what I have clearly been hearing is these methods work. The one
that seems most unlikely to you, attaching this foil-like material to
the underside of the roof decking, is to the best of my knowledge the
most effective method for adding to an existing home. Of course if you
are building new construction, or re-roofing and can consider
replacing the decking, you probably would find it better to buy the
roof decking that has the foil underside.
Evidently the shiny side must face an air space for it to work. The
downside of laying the barrier horizontally on existing attic
insulation, is that it works fine the first day, but it soon will get
dusty and become less effective.
Usually we assume asphalt shingles when we talk about radiant
barriers. If you happen to have a different roof material, we ought to
stop and reconsider. I have read that tile roofs have advantages which
lessen the effectiveness of radiant barriers and attic ventilation.
Probably metal roofs as well.
It is my understanding that spray-on radiant barrier paint cannot be
as reflective as foil stapled to roof rafters or on decking material,
but its ease of use may be attractive for retro-fit jobs. Tom Tynan
endorses spray-on radiant barrier paint on the underside of your roof
So far as I can tell, Tom agrees that foil based roof decking is
superior for new construction. I believe stapling foil type material
to the rafters, will provide superior performance but it might be so
much extra labor that costs outweigh the benefits.
You might find the following article from the Florida Solar Energy
Center (FSEC) interesting. All that I have seen from FSEC appears high
quality practical research, in my opinion:
I must say that I am a total amateur and am merely passing along
things I have been taught which sound right. Am thinking about putting
up foil type radiant barrier in my house but have not done the project
yet. Am somewhat thinking about retro-fitting "skin venting" to our
exterior walls but first must find someone with professional
credentials who will endorse such a project. If anyone finds fault
with what I have said, it will be to everybody's benefit to correct
Thanks and good luck -- Mark J.
--- In email@example.com, "Roxanne Boyer" <rox1@a...> wrote:
> I am looking for ways to reduce the cooling energy costs of my home.
I have heard about radiant heat barriers in the form of:
> 1) Exterior coatings (put on the paint or shingles) that reflect
> 2) Foils that are applied to the underside of the roofing board -
either sprayed or stapped in sheets - that reflect infared radiation.
> 3) Foils that cover the attic floor on top of the insulation that
also reflect infared radiation.
> Does anyone have any experience with these applications? Do they
work? How much does it cost to have them installed?
> Theoretically the radiant barrier on the exterior of the roof and
the radiant barrier on the attic floor should work. I don't see how
the foil/spray on the bottom of the roof could work.
> Chris Boyer
> "Conservation is a great alternative fuel."
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