What Are The Benefits Of An Attic Radiant Barrier?

When your attic gets hot, it can really affect your electric bill. The same goes for the winter months if your attic won’t hold the heat. You can practically watch the meter spin. A well insulated attic can help prevent a lot of this but there is one thing you can do to save yourself even more money. You can install a radiant barrier in your attic.

What is a radiant barrier? Well, they are not new. They have actually been around since the 1960’s and were first developed by NASA for use on astronaut spacesuits. They were later used in commercial and residential structures and are a proven way to reduce heat loss. Tests done by the Florida Solar Energy Center and Oak Ridge National Laboratories have proven radiant barriers to be very reliable. But what are the benefits of a radiant barrier in an attic? First, let’s look at what exactly a radiant barrier is and how it works.

What Is A Radiant Barrier

Radiant barriers are reflective materials that are installed inside buildings to reduce heat build up during the summer months and to reduce heat loss during the winter. Their biggest benefit is during the summer when your attic gets so hot. By reflecting the heat back out from the house, radiant barriers can keep the temperature in the attic down which will save you on your monthly electric bill because it saves on the work your air-conditioning has to do. Radiant barriers are used in all types of residential, commercial, and industrial buildings.

Types of Attic Radiant Barriers


Attic adiant barriers usually consist of a thin sheet or coating of a highly reflective material such as aluminum that is applied to a type of backing. Some types of attic radiant barriers are fiber reinforced to increase the durability and make them easier to handle. The most common type of radiant barrier material is a multi-layer of aluminum foil with a foam-like backing. The radiant barrier comes in a roll, pretty much like a giant roll of foil for your kitchen. If there isn’t a durable backing then the foil will tear easily. Multi-layered foil barriers might use a central layer of foam, plastic bubbles or fiberglass for additional insulating value. This kind of insulation is very effective because it gives your attic protection from both radiant and conductive heat. You can also get foil roof sheathing that acts as a combined decking and radiant barrier.

How Does A Radiant Barrier Work

The reason your electric bill goes up is because when the roof gets very hot it radiates solar heat down into the attic insulation. During particularly hot days, solar energy is absorbed by the roof which heats the roof sheathing. This causes the underside of the sheathing and the roof framing to radiate heat downward toward the attic floor. Conventional attic insulation such as fiberglass, foam, and cellulose reduce this heat transfer by trapping warm air. The problem with this is as the heat trapped in conventional insulation during the day will radiate down through the ceiling and into your living space at night even after the outside air has cooled down. This means you will have to run your air-conditioner at night which wastes energy.

A radiant barrier works by reducing the amount of solar heat that gets through the roof and build sup in the attic. An aluminum foil barrier will block up to 97 percent of this heat from reaching the insulation and thus radiating into the air-conditioned living space below. Radiant barriers can be placed on the underside of the roof deck or you can even place it directly on top of the conventional insulation on the floor.

All of this works out to give you several benefits. The most important, as stated, is to reduce the cost of heating and cooling your home. Another benefit of radiant barriers is they increase the comfort level of your home because you are not sweating or freezing. Radiant barriers also help the environment by making your home more energy efficient. Also, these barriers can help protect your attic from damage caused by high levels of heat.

How Is A Radiant Barrier Installed

Radiant barriers can be installed in your attic in several different ways. Since the barrier comes in a large roll, the easiest thing to do is to lay it directly on top of existing attic insulation which is on the floor. You want to make sure that you lay it with the reflective side up. Another way to install a radiant barrier is to attach it near the roof. There are a couple of ways you can do this. One way is to attach the radiant barrier to the bottom surfaces of the attic truss chords or rafter framing. Another way is to attach the radiant barrier directly to the underside of the roof deck which usually has no insulation. You will want to put the reflective side towards the roof. If your house is in the process of being built, you can put the radiant barrier over the tops of the rafters before the roof deck is nailed down.