All barriers across both categories can feature a reflective surface on one side (single-sided) or both (double-sided). Aluminized plastic films are made up of aluminum particles that are deposited on plastic film. These are often laminated to the underside of the OSB and perforated to allow water vapor to escape the attic. The former comprises oriented strand boards (OSB) coated with foil to make them reflective. There are several types of barriers, and most of them can be neatly pigeonholed as either aluminum foil laminates or aluminized plastic films. Failure to include this minute but critical space will result in a radiant barrier that funnels heat into the attic, which is the exact opposite of what we want. A good analogy for this is how heat from your coffee travels up the stem of your teaspoon. It is important to remember that while the barrier keeps out radiated heat, it can still transfer heat to anything it comes in contact with via conduction. The airspace is necessary to prevent the barrier from touching the rafters and other ceiling parts. For it to work correctly, the barrier must be separated from these other roofing materials by airspace.
The radiant barrier was invented to prevent the radiated heat from being absorbed by the rafters and insulation layers below. Because an attic is at the top of a building, most of the natural heat it receives is radiation from the sun in the form of ultraviolet (UV) rays.Īs the roof is continually exposed to sunlight, the heat is absorbed and transferred through the roofing material (conduction) and into the attic air (convection). You can transfer heat in one of three ways: radiation, conduction, and convection. They are popular because they reduce the need for costly and energy-consuming cooling solutions like air conditioning. In attics, they are often lined on the inner sides of roofs. They are a thin layer of materials that feature highly reflective surfaces, such as aluminum. Radiant barriers are building materials that reduce heat transfer and reflect thermal radiation outside. You can’t fully measure the value of a radiant barrier in dollars and cents. Not to discourage you from installing radiant barrier decking in your existing or new home. Also, little testing has been done in hot, arid climates such as the southwestern United States.” 1 So far, very little testing has been done in climates colder than that of Knoxville. “ The ORNL tests included summer and winter observations. The Oak Ridge National Laboratory working in conjunction with the Department of Energy, has published some of the findings regarding the testing of radiant barriers but states that not enough testing has been performed north of Knoxville, Tennessee, and the southwest. This is often directly reflected in lower monthly energy bills. While doesn’t cite the source of these studies, here in South Carolina, I’ve seen firsthand that inside attics with a radiant barrier decking can be as much as 25 degrees cooler than attics without.
They state that, in cooler climates, it’s more cost-effective to install more insulation instead of a radiant barrier.
No significant savings have been shown in colder climates however, other benefits still make radiant barriers worthwhile.Īccording to, some studies have shown 5% to 10% energy savings in warm weather climates. Radiant barrier decking has been shown to save homeowners 5% to 10% on utility bills. The benefits of radiant barrier decking are greater in warm weather climates and lesser in cold weather climates. But is the added cost to install a radiant barrier sheathing worth it? How much savings can you expect on energy bills? Today, many new construction homes install radiant barrier decking to reduce heat gain and lower the home’s overall energy costs.