Radiant Barrier

What is a Radiant Barrier?

Radiant barriers are effective in reducing summer heat gain and cooling costs when installed in homes, typically in attics and on wall decking. These barriers are made of a highly reflective material that reflects radiant heat instead of absorbing it. It's important to note that while radiant barriers can reduce heat conduction, they are different from thermal insulation materials that specifically target heat conduction.

AtticFoil can be effectively used on sun-catching walls to enhance the comfort and efficiency of homes during summer. It serves as a radiant barrier that reflects radiant heat, helping to keep the interior cooler. Additionally, AtticFoil can be applied as a house wrap on the exterior of a home or building, further maximizing comfort by reflecting radiant heat on all sides. When used as a house wrap, it is recommended to use a perforated foil to allow for drying of the wall assembly. In retrofit applications on homes with vinyl or Hardie board siding, AtticFoil can be installed as a secondary drainage plane and air barrier over traditional house wrap, such as Tyvek. This combination can help improve the energy efficiency and performance of older homes or buildings.

When installing a radiant barrier behind siding, it's crucial to ensure proper air circulation and create an airspace for the radiant barrier to be effective. Claddings or exterior sheathing should be open to allow for air movement. To achieve this, furring strips, which are thin wooden strips, can be installed perpendicular or parallel to the wall studs to create the necessary air space behind the siding. Without this air gap, the radiant barrier will not work optimally.

When installing the radiant barrier house wrap, it's important to place the foil closest to the source of heat you want to block, which, in the case of an exterior wall, is the outside. Typically, siding materials do not have a natural air gap, so one must be created. This can be achieved by using wooden furring strips to provide approximately half an inch to an inch of airspace. If the siding has a beveled or naturally occurring air gap of at least half an inch, furring strips may not be necessary.

Creating the proper airspace behind the siding ensures that the radiant barrier functions effectively in reducing heat transfer and improving energy efficiency in the home.

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Step-by-Step Process for Radiant Barrier Siding

When installing a radiant barrier behind siding, the layers should be arranged as follows from the outside to the inside:

1. Siding (or Hardie Board)
2. Air gap (created using spacers)
3. AtticFoil™ radiant barrier (double-sided or single-sided, with the foil side facing outward towards the air gap)
4. Optional Tyvek® wrap
5. Studs/board
6. Interior wall cavity

It's important to maintain the integrity of the air gap for the radiant barrier to function effectively. Stretching the foil tightly across the studs without any sagging is recommended. The foil can be stapled to the wall studs or board first, followed by the installation of furring strips and then the siding material (vinyl or Hardie board).

This layering technique allows the foil to utilize its reflectivity to block incoming heat from entering the wall cavity. By using AtticFoil™ as a house wrap, you can prevent up to 97% of radiant heat from entering your home. The foil acts as a barrier against liquid water while still allowing water vapor to pass through, providing the benefits of a Tyvek® wrap along with the added advantage of blocking radiant heat.