Thoughts and Opinions on Radiant Barriers and Foil Insulation

At InsulationStop.com we have strived to provide the highest quality reflective foil insulation on the market. We offer the industries largest diversity of foil products ranging from 16” wide rolls to 48” rolls. As well as offering different widths and lengths, our products also come in different types such as single bubble, double bubble, reflective/reflective, or reflective/poly.

Our website is designed to help you choose the correct product for your insulation project. As with all insulation, there are slight product differences as well as different installation methods. This page is designed to help you understand these differences in a non-technical format.

First, all reflective foil insulation is NOT CREATED EQUAL. There is an increasingly wide range of reflective foil insulation products on the market today. There is also a wide range in the quality of reflective foil insulation products. Use caution in the quality of products you purchase and in the way they are installed. In our opinion, all reflective foil products should conform to the ASTM E84 Fire Rating Test. Products of this class achieve a Class A/Class 1 fire rating. A great way to compare product attributes is by measuring ASTM testing performance data.

Secondly, you can and should use reflective foil insulation anywhere you would use fiberglass insulation. Installing reflective foil insulation in conjunction with fiberglass installation is an excellent way to achieve your max insulating value. You help stop the convective and conductive heat transfer with the fiberglass insulation, and stop the radiant heat transfer with the reflective insulation. Do not think that you should use one product or the other. If in your application you can use both, you should. The nice thing about insulating an area is that you only have to do it one time. You should do the best job you can for optimal performance.

You should also use reflective insulation in areas you cannot use fiberglass such as in concrete and crawl-space application; under carpet and radiant heated floors; duct work insulation, and in metal building applications.

Please review the following applications to see what we think is important in product quality and installation methods.

Attics: In these cases use a radiant barrier product. There is typically no need to use a bubble product. You are essentially making wide runs down the length of the attic. Wherever you have or leave an air space with the fiberglass insulation (ridge or soffit area), do the same with the reflective foil. Make sure you are using a quality product here. Our product has an interwoven polyethylene mesh making it virtually tear proof. This alone will make installation much easier as well as giving life long durability and tear resistance. Make sure all seams are taped with a high quality reflective foil tape. Use either a perforated or non-perforated product depending on your specific application. Please see our attic installation instructions on the product page.

Duct Work: In these cases use a double bubble, foil/foil product. The R-Value attainability referenced on the product pages can only apply with a double bubble product. However, wrapping your hvac duct work in reflective insulation will yield excellent results, regardless of single or double bubble. The important note is this. Installation is the key. Use, if you can, some form of spacer method allowing a small airspace. Use a high quality product and make sure all seams are taped. Please see our available installation instructions on the product page.

Radiant Barriers and House Wraps: In these cases, you are obviously using a radiant barrier product. There is typically no need to use a bubble product. You are essentially encapsulating an area using a roll of foil product. If you choose a non-perforated product you will have vapor barrier qualities as well as reflecting radiant heat. This is why reflective foil radiant barriers whether perforated or non-perforated are superior to normal vapor barriers or house wraps. These products meet the requirement of a vapor barrier or house wrap but also block radiant heat. Use a high quality no tear type product for long life and ease of installation. Please see our radiant barrier and house wrap installation instruction on the product page.

Wall, Joist, and Crawlspace: In these cases use either a single bubble or double bubble product. As always, choose a high quality product. High quality products offer excellent bubble pressure and tear resistance ensuring life long quality and performance. For installation, either choose a tabbed product in smaller widths to go within a wall cavity or choose larger widths to run across the face of a wall cavity. Generally, running reflective foil insulation within a wall cavity using smaller widths is easier to install but more expensive then running the larger width material across the face. Regardless of choice, make sure all seams are taped. Please see our installation instructions on the product page.

Commercial and Metal Building: As with all insulation, the same products used in residential applications are used in commercial applications. A major consideration however, is in the possibility of choosing a reflective/poly type product. This is generally used in metal buildings or pole barns where the insulation is visible. Utilizing White poly on the interior side of the application results in a white finished looking interior which is excellent for human or animal occupancy. Use either a single bubble or double bubble product. As always, choose a high quality product. High quality products offer excellent bubble pressure and tear resistance ensuring life long quality and performance. Make sure all seams are taped. Please review some of our installation instructions. Use relevant residential application instructions and applicable installation methods.

Floor and Radiant Heat Insulation: In these cases, you can use any reflective foil insulation product that meets your specific needs. As always, we recommend the use of a double bubble product. In general, use reflective/reflective unless your application would call for the use of a reflective/poly product. Tape all seams. Using properly installed reflective foil insulation in basement flooring applications also creates a perfect radon barrier as well as reflects radiant the heat. Please see our available installation instructions on the product page.

Concrete Applications: In these cases your application determines your product. Under slab applications require a specific product choice. You should not use a reflective/reflective type product in under slab applications. The chemical reactions resulting in the curing of the concrete can damage the reflective side of the insulation. We offer a patented bubble/reflective/bubble product that is designed specifically for under slab applications. Regardless of your choice, if you are using reflective insulation to insulate under a concrete slab you need this product or a reflective/poly product with the poured concrete going over the non-reflective side of the installation. Tape all seams. Use Poly Tape instead of reflective foil tape to tape the seams in an under-slab application. Always use a double bubble product in these applications due to the pressure on the material from the slab. In wall applications, refer to standard wall application and product instructions. For above slab applications, refer to flooring applications. As always, use the highest quality product possible.

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