Do Radiant Foil Barriers in an Attic Save Energy?

Do aluminum foil radiant barriers in an attic really work, and will they reduce my heating and cooling bills? – Murray

Hi Murray,

Radiant barriers work by reflecting the heat coming through your roof on sunny, summer days. Unlike fiberglass or cellulose insulation, radiant barriers do little to prevent the conduction of heat or cold through the air and have no R-value.

While not a substitute for traditional attic insulation, radiant barriers may reduce your air conditioning bill by 5% to 10% (according to the U.S. Dept. of Energy) if you live in a hot climate. Radiant barriers have little or no effect on cold air or heating bills in the winter.

There are several types of radiant barriers available, including:

  • Reflective metal roofing
  • Radiant roof sheathing
  • Metal (aluminum) foil

Foil radiant barriers can be applied on top of rafters in new construction before the roof sheathing is installed, or on the underside of rafters on houses with an existing roof.

Don’t install a radiant foil barrier on top of attic insulation, since condensation can form under it (even on perforated foil), resulting in a buildup of moisture, which can reduce the effectiveness of insulation and cause moisture damage and rot.


Further Information


  1. Hi.
    Why can’t we use aluminum foil based insulation material on top of house facing the sun directly, instead of inside home (in hot countries)? Because aluminum has the nature to reflect radiation from sun. Are there other impacts on the foil from direct sunlight? Please clarify on this.
    Thank you.

  2. Could you place the foil on the attic floor under the insulation, while creating 2 air corridors on both sides to remove the chance of condensation.

  3. I am a senior citizen and have an older home and not much insulation showing in attic I am interested in lowering my heat bills. I have had an estimate on installing therma shield in my atttic and was told it would lower my heat bills but I am reading it mostly lowers cooling costs. This is expesive and need your advise. Thank you


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