Ask The Expert: How Do I Install Radiant Barrier in My Attic?

Posted by Ecofoil on

Barb Rawson, Product Specialist Barb Rawson, Product SpecialistI have customers ask me this on a daily basis. Many people are unsure of whether their EcoFoil perforated radiant barrier should be installed on the rafters or on the floor of the attic. Both applications will work to keep radiant heat out of your home. However there are some things that need to be taken into consideration when choosing which method is best for your situation.The first question I ask is, “What area of the country do you live in?” This tells me a lot about what the consumer is looking for. A large number of our customers are in the southern U.S. and want to protect their homes from the heat.If this is the case the answer is simple. Your primary goal is to keep the heat out of your attic; therefore the best choice for installation is on the rafters. This is especially true if you have any HVAC units or duct work in the attic. To maximize efficiency and extend the life of your furnace/ac unit, these ducts should also be insulated with EcoFoil Big 8 duct insulation.The rafter installation is the most efficient method to keep heat out because it stops the heat as it enters the attic and reflects it out before it can heat up the mass insulation below. This keeps the overall attic temperature down considerably. This installation method is also preferred if the attic has a functional floor and is used for storage.The following instances are those in which the floor method might be a better solution:• Climates with hot and cold extremes• Steep roof pitches with peaks that are difficult to reach• Complicated roof truss designsIn these cases you can choose to lay the insulation on the floor of the attic. In cases of extreme climates, the foil will help to minimize heat loss in the winter time. The attic will still be affected by radiant heat; however the radiant barrier will prevent it from entering the living space.Whichever method you choose be sure to install EcoFoil perforated radiant barrier in a way that does not inhibit the attic’s natural air currents. Attics are typically designed so that cool air enters through soffit vents and hot air exits through the ridge vent. This will also allow any humidity to escape. Follow the following guidelines to properly install your perforated radiant barrier:
  • Do not overlap or tape the seams.
  • When installing on the floor of the attic lay the radiant barrier perpendicular to the joists andleave a 3” gap between the sheets to allow air flow.
  • When installing on rafters, do not cover the 6” adjacent to the ridge or soffit vents.
  • Don’t forget to insulate the gable or knee walls.
 For ultimate control of heat transfer some customers choose to add perforated radiant barrier in both locations to take full advantage during all seasons of the year.Not only are our products are manufactured in North America and have a 10 year warranty, but we also strive to provide the industry’s best customer service. Our centrally located warehouse allows us to ship to the east and west coast of the U.S. within four business days so you can keep your projects running on time. If you have more questions or would like to order EcoFoil perforated radiant barrier call us at 888-349-6264 or visit