Should I Get Aluminum Mylar Insulation in My Attic?

Application

• Radiant barriers create a reflective surface inside your attic that redirects heat away from the living spaces of your home. These barriers are installed above the rafters of your attic or below the roof deck with the reflective side facing the open space of the attic. Individual brands and types of radiant barrier are rated based on their emittance and reflectivity. These measures define how much heat the insulation emits and reflects. Aluminum mylar insulation typically has a low emittance and high reflectivity, making it an effective form of radiant barrier.

Installation

• There are several options for installing radiant barriers. If you are replacing your roof deck or building a new home, you can purchase roof deck panels with a pre-applied radiant barrier or install aluminum mylar sheeting between the attic trusses and the roof deck. In an existing house you can staple aluminum mylar sheeting to the underside of the roof decking or attach it to the underside of your attic trusses. You can also install a radiant barrier across the floor of the attic if it is relatively clear of obstructions.

Limitations

• Radiant barriers are effective at reflecting heat from the sun away from your home, however their benefits are often limited. A properly installed radiant barrier can only reduce your energy costs relative to the amount of heat absorbed through the roof. In cool climates or areas that are heavily shaded, radiant barriers are less cost-effective than other types of insulation.

Considerations

• Adding insulation to the roof deck is usually more expensive, since the roof deck has a larger area than the attic floor. Although installing aluminum mylar insulation across your attic floor is cheaper and easier, it has several drawbacks. Over time radiant barriers on the floor will collect dust, reducing their effectiveness. Any items stored on top of a radiant barrier will also reduce its effectiveness, limiting the storage space in your attic. Aluminum mylar insulation performs better in attics that are well ventilated. If you add insulation to the underside of your roof deck, make sure that you do not block your vents.