Some like it Shiny
When it comes to energy efficiency and the roof, the city of Dallas provides three options.
Professionals can install radiant barrier under the roof deck, spray foam insulation with a minimum value of R22, or Energy Star-rated roof shingles.
As you can see, the ModelReModel went with the first option.
The use of radiant barriers varies between regions, but it’s a product that’s seen big gains in popularity over the past few years. However, there are still a lot of misconceptions about what a radiant barriers does and its strengths and weaknesses. Here are three things you should know.
Foil radiant barriers lower the radiant heat gain in an attic and can reduce the temperature by an impressive 20-40 degrees. But, in order to do its job, a radiant barrier needs to have an air space next to at least one of its reflective surfaces. If the shiny area comes into contact with another surface, it will act like a metal spoon in a pot of hot soup, conducting heat and actually increasing the attic’s temperature. According to RIMA (Reflective Insulation Manufacturers Association) International, you should "never install a radiant barrier with its low-e surface in complete and direct contact with other materials."
Next is the question of dust. A radiant barrier can be placed right on top of the insulation on the attic floor or stapled to the bottom of the roof rafters. While the first option is easier to install, it also accumulates more dust, which cuts down on the product’s effectiveness.
Radiant barriers reflect heat and this causes a slight increase in the temperature of roof shingles—about 2-5 degrees. When the product was first used, there was some question about whether the shingles would be affected, but that has ceased to be a concern. No shingle manufacturer limits their warranty due to the use of a radiant barrier, according to the RIMA International.