Hi Ross. I have been working with a radiant barrier coating for 25-years now. Our coating goes on like paint, looks like paint and can be used as interior or exterior paint or as a roof coating. What makes ours exceptional is that it is not only a radiant barrier, it is an extremely effective as a conductive heat barrier also.
It retains heat in the winter.
I will be happy to send you a small cured sample if you would like to experiment with it.
My contact information is on my profile, so is our websites.
There are two factors I can think of when talking about radiant barriers:
1) Radiant barriers reflect heat both ways (in the winter they preserve the heat inside, which might be good)
2) When installing a radiant barrier right under the roof it will work to raise the temperature of the roof, which is also a problem if you have just a hot roof. And the problem is - your roofing will not last nearly as long when it's this much hotter. The way to go is to make the roof surface reflective.
I have 25 years of working with our radiant barrier coating / paint. We do every type of residential and commercial roof except wood shingles. I agree with you that a reflective barrier beneath a roof will make the roof hotter and give it a shorter life than expected.
However, when it comes to a radiant barrier coating applied to residential sloped roofs, hardly anyone wants a bright white roof. It shows evert little bit of dust, every pine needle and spot of bird poop, the neighbors hate it. We normally tint it with a few drops of brown, blue, or green and then the neighbors dont seem to mind.
Our coating is nor just a very effective radiant barrier, it is also an extremely effective conductive heat barrier.
Now, nefore I start on this aspect I want to state that if you talk about a radiant barrier roofing material that gets temperature reductions and resulting energy calculation that come out to more than 10% to 15%, people think you are nuts. We get calcs of 50%+ and have been getting that for 25 years.
As a conductive heat barrier, our coating has been applied on top of the black felt paper on new roofs and re-roofing projects and results in temperature reduction that come out to 38% to 50% year round. It can also be applied to the plywood before the black felt it installed and the same results.
We have found out over the years that by painting the sheetrock walls and ceilings in the building is the most effective way to uitilize our product and get the maximum energy savings year round.
We have had our reflective coating on the roofs of casinos in Las Vegas for over 20 years and they are just as effectrive and look the sam as the first week they were installed.
As far as applying ours to the felt or the plywood under the felt, their is no protection from the UV rays to the shingles as they will absorb that heat energy and will be unable to trasfer it to the inside of the building. That equals a hotter shingle and a reduced lifespan of the shingle.
We have alot of information on our website on what we do.
Our distributor in Texas can go anywhere in the US. It will never be available 'Off the shelf". It is a specialty coating and an elastomeric. If people treat it like paint, they will have some problems. It is 30 times thicker than paint, 65% solids. The formula is very sensitie to the addition of water, even though it is water based. Add 1 cup of water to a 5 gallon buchet and you just ruined it, it will lose its elastomeric properties and will not bond well.
We have a sales representative in Maryland. Our distributors in Texas or California can ship it anywhere.
At the risk of drawing the ire of the folks on here who sell radiant barrier products, everything I've learned has told me that a radiant barrier in cold climates like ours (I'm in Iowa) is a waste of money. We have had a number of firms selling various products in our area, and I've run across it in several home energy audits. In one case, a customer spent over $3,000 to put a radiant barrier on top of his attic floor when all he had in the floor cavity was 4" of cellulose! In other words, for a third of the cost he could have increased his attic R value to R-49+ and saved WAY more energy than the radiant barrier would save him!
Here's a link to a fantastic article about radiant barriers that you should read: http://www.greenbuildingadvisor.com/blogs/dept/musings/radiant-barr...
Thank you so much for directing me to this article. It is clear, the best practice is to put your money into insulation. I like the fact that the writer sited some studies he had found.
the US DOE at Oak Ridge National Lab, ONRL, have done some good work documenting the value of these in all 8 climate zones. See the web page at http://www.ornl.gov/sci/ees/etsd/btric/RadiantBarrier/index.shtml
It also has a good "pdf" of the article.
Living in Minnesota myself I can appreciate the lure of a "silver bullet", but this aint it.
As others have said: Air seal and insulate are they way to go in Our climate zones of 6 & 7.