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Frequently Asked Questions

An R-Value is a measurement of resistance to the flow of conductive heat transfer. Since Radiant Barriers are designed to reflect radiant and not conductive heat, they do not have an actual R-Value. Any "theoretical" or "equivalent" R-Value depends heavily on the method of installation and the size and number of airspaces surrounding the material. We do not attempt to assign any R-Value to Radiant Barrier as it is not relevant and somewhat misleading. It is the RB's ability to reflect radiant heat that makes it such an energy saver.

It depends on your particular climate and application. If you are installing the Radiant Barrier on the outside/exterior of mass insulation, you generally want to use the Perforated type so as not to trap moisture within the wall. If your climate or local codes call for an interior vapor barrier, you can install the Non-Perforated type on the inside/interior of mass insulation. In this case you would also tape the seams to create a vapor barrier. We recommend using only perforated radiant barrier in all attic installations.

Yes, the holes are very small and do not degrade the performance of the RB. They are there just to allow moisture to pass through and have virtually no effect on the thermal performance.

When using Radiant Barrier as a Vapor Barrier or house wrap, it is important to seal all the seams. You will need approximately 1 roll of tape (2" x 150') for every 1000sf of Radiant Barrier.

Yes, provided that it is installed with an air space on both sides. There are two properties which allow radiant barriers to work, reflectivity and low emissivity (low-e). Heat is reflected on the top/hot side, and since RB has a low-e value, heat is not emitted to the bottom/cold side. Of these two properties the low-e value is of greater importance. In order for a radiant barrier to be most effective in both summer and winter it needs to have aluminum on both sides. According to a study performed by a Texas A&M University professor, double sided radiant barriers were nearly 50% more effective than their single sided counterparts.

Your actual savings will vary with many factors including: attic installed location, house shading, duct leakage, air handler location, geographic location, etc. In the South, you can expect to see a 40% reduction in heat gained through the ceiling. This can translate to a 17% savings on cooling bills. In some installations, there will also be additional savings on heat which will no longer be lost through the ceiling in the winter.

The Radiant Barrier will only increase the roof surface temperature by 2 to 5 degrees. To put it in perspective, the surface temperature of dark asphalt shingles can reach 190°F on a hot sunny day. Most roofing manufactures recognize that adding radiant barrier to your attic will not harm your shingles.

The most important specification to look at when comparing different types radiant barrier is the emissivity value. The best radiant barrier paints have an emissivity value of around 0.25, while our radiant barrier foils have an emissivity of 0.03. The lower this value, the better it works at blocking and reflecting heat. In other words, the best paint products can only stop about 75% of the radiant heat, while our foil products can block up to 97% of the radiant heat. In fact, to even be considered as a true "Radiant Barrier", a material must have an emissivity of .1 or less. The paint products fall sort of this mark. Compare Foil vs Paint

There are some vendors which suggest to use radiant barrier instead of regular insulation, but we always recommend using it in conjunction with regular insulation. The reason is that they work to perform different functions. Regular insulation primarily slows down conductive heat transfer, but does not prevent radiant heat from penetrating. Radiant Barrier blocks radiant heat, but not conductive heat transfer. A good system utilizes both radiant barrier and mass insulation to reduce both types of heat gain or loss.

All of our radiant barrier materials are double sided (foil on both sides), so it will not make any difference which direction you install it. However, if you were to install a single sided product, the foil side should face down towards the attic space.

While attic ventilation plays an important roll in relieving moisture and excessive heat buildup, it is not a requirement for radiant barrier to work. Radiant barrier will reflect the same amount of radiant heat even in an attic with no ventilation.

Yes, very little of the radiant heat is captured or removed by air. Radiant heat travels in the form of waves through space until it is absorbed or reflected by a solid surface. So even in a well ventilated attic, without radiant barrier installed your home will still suffer from excessive radiant heat gain.

We get this question several times a week. I know of at least one website recommending this type of installation. Unfortunately, without the required air space adjacent to the foil, the heat will simply conduct through the foil. There are a few types of roof systems utilizing purlins that do allow for this air space.