Radiant Barrier FAQs


icon_q Do I have to install your radiant barrier shiny side up?

icon_a No. Radiant Barriers work by reflecting infra-red energy which is not visible light. Most products have one shiny side and one dull side. This finish look is created in rolling mills, when they make the aluminum sheeting. Both sides could be dull and they would work the same.

icon_q Will the radiant barrier work if I use it in place of the felt, when I replace my roof?

icon_a No. All Radiant Barriers must face an airspace on one side to work. That space can be as small as 3/4" but, it is the foil surface AND the air space it faces that together become the barrier. If you used barrier material in place of felt you would have two problems:

First, if the metallic barrier material is in direct contact with the roofing material on one side and the roof sheathing on the other, it will act as a conductor for heat rather than a barrier.

Second, the local building dept. might be unhappy with you for using a product that is not approved for that installation. Being approved as a good vapor retarder, as all our RB products are (unperforated), doesn't qualify them as underlayments.

icon_q Can I install your products directly under my roof sheeting?

icon_a Yes, but only the two products that are offered perforated. The foil side, of the Aluma-Foil HD product must, face the airspace below. The perforations in this type of installation are necessary to prevent the trapping of moisture in the roof that may pre-exist in the OSB or plywood sheathing. This is a very popular method of installation in either new construction or re-roofing of an existing structure. Do not forget to install RB on the gable ends and knee walls when installing in this method.

icon_q How important is venting in my attic?

icon_a Very. The primary reason attics are vented to begin with is to remove moisture that moves into your attic from your home below. Without venting, damage could develop in the form of mildew and dry-rot over the years and be both unhealthful, as well as very expensive to repair. A good rule to remember is to allow one square foot of ventilation for every 150 square feet of roof area. Good venting will improve the performance of your radiant barrier and insulation.

icon_q How do I know which radiant barrier is best for what I want to do?

First of all, all radiant barriers perform the same, as long as their emittance is the same. It doesn't matter whether they have a paper core material, a bubble, mylar or any other substrate. They all do the same thing. It is a matter of cost, handling and how the manufacturer warrants their product. Don't be afraid to ask a manufacturer for a specification sheet and sample of the product your choosing. All attic radiant barriers must have a Class "A" flame spread rating and if they are to be used as a vapor retarder also they must have a rating of 1.0 perm or less. All aluminum foil sheeting has an emittance of .02 to .05 and a reflectance of 98-95%.

icon_q Are moisture and dust a problem if I lay a radiant barrier on top of my existing attic insulation?

icon_a Moisture should not be a problem as long as you use the Super Plus perforated product. This should adequately remove the moisture moving from your home below into the attic above. The dust issue is simple. If you live in an area that is windy, and dusty, you will have a problem. Because of this and the fact that we cannot tell you how much a problem this might be we do not recommend this application technique. Dust is very conductive and will reduce the reflectance over time.

icon_q If I have ducts in my attic, above my insulation, should I cover them with RB?

icon_a Absolutely, the average duct, if it is insulated at all, will only have an R-3 to R-5 insulation wrapped around it. That is considerably less than the insulation below it! And, its closer to the source of heat gain in the summer. Who knows why anyone would built like that! RB will greatly improve your energy savings when you wrap the ducts. However, if the ducts are already wrapped in foil, even if they only have an R-3 or R-5, you don't need to wrap them again.

icon_q What other uses are there for your radiant barriers?

icon_a Many. You can put it on the back of your garage doors to knock down the heat. Its excellent for wrapping water heaters, pipes, lining crawl spaces, ferring pens, pole barns, tool sheds, airplane hangars and many other applications. It can also be used in walls and floors, as long as a minimum airspace of 3/4" is allowed between the building material and the foil surface. Anytime you want to prevent heat gain, or heat loss, you probably should consider using a radiant barrier.

icon_q What about using "foil chips" in my attic ? Wouldn't that be just as good as laying down your product on my existing insulation?

icon_a No. Some manufacturers claim their product performs better than other RB products and that they are not subjected to such problems as dust on the surface, affecting its performance. When in doubt, you need to demand that the seller provide you with acceptable test data on their product. Compare and don't be taken in by false claims. For example, all RB products installed in attics must have a flame spread rating of 25 or less according to UBC (Uniform Building Code). That means the supplier must be able to provide you with a copy of this test if you request it. When in doubt, ask them to supply documentation! Those companies who sell radiant barriers in the state of California must also be approved, and listed, by the State of California, Bureau of Home Furnishings.