Radiant Barrier Questions & Answers

How Do Radiant Barriers Work?

• Radiant barriers are installed into an open airspace in the home, typically an attic. The barrier should be installed perpendicular to the radiant energy striking it to ensure optimum performance. For example, affixing barriers to the rafters will place them perpendicular to the heat emitted from the roof. The reflective surface of the barrier reduces the transfer of heat into the open airspace. Without this barrier, hot attic air would heat insulation, which would then transfer heat into the living space through the structure.

How Are Radiant Barriers Constructed?

• Radiant barriers are generally constructed of substrate materials such as plastic film, kraft paper, oriented strand board or cardboard with a highly-reflective layer on one or both sides. The reflective material most commonly used is aluminum. Some manufacturers offer radiant barrier chips or thermal control membranes but they are not widely used. Radiant barrier chips have several reflective sides, which allows the chips to rest at an angle, reducing the possibility of dust buildup on a single side. Dust buildup will reduce the effectiveness of the barrier.

How Are Radiant Barriers Installed?

• Installation of radiant barriers is easiest and most effective in new home construction. Rolled-foil barriers are draped over the rafters with the reflective side down and allowed to droop slightly, usually about 1 inch. This is done just before the roof sheathing is installed. Affixing the barrier to the underside of the rafters is utilized if installed after the roof is completed. By installing with the reflective side down, dust will not accumulate on the surface and reduce the effectiveness of the barrier. Radiant barrier chips can be blown into an existing attic space.

What Are the Benefits of Radiant Barriers?

• A properly installed aluminum foil radiant barrier can block approximately 95 percent of the heat radiated from the roof. This keeps your attic insulation cooler and prevents radiant heat from affecting the temperature of your living space. The result will be a more comfortable home and lower energy costs. Radiant barriers can also help reduce the temperature of uninsulated, non-air conditioned or unheated spaces such as your garage, workshop or attic storage space by reducing the amount of radiant heat allowed into the space.

How Much Do Radiant Barriers Cost?

• The cost of installing a radiant barrier will vary depending on factors such as type of the barrier selected, amount purchased, installation method and labor costs. According to informal surveys conducted by the Florida Solar Energy Center, the cost of radiant barrier materials ranged from $0.07 to $1 per square foot. Installation costs ranged from $0.10 to $1 per square foot.