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Frequently asked questions about Radiant Barrier and Reflective Foil Insulation

What is a radiant barrier?

Radiant barrier is a layer of reflective foil insulation made up of 99.9% pure aluminum that is placed in an air space to block radiant heat transfer between a heat radiating surface (like the sun) and a heat absorbing surface (like the air inside a building). Reflective foil is made by adhering a coating of 99% pure Aluminum metal to a tear-proof polyethelyne fabric to create a surface with high reflectivity (96%) and low emissivity (4%).

What is the difference between solid radiant barrier and perforated radiant barrier?

Perforated radiant barrier has tiny perforations in the material every 1/4" that allow permeability for water vapor and should be used anywhere that you do not need a vapor barrier in your application. In attic applications perforated radiant barrier is the best product as it will help prevent the build up of condensation that could cause ice dams and mildew.

Solid radiant barrier is the same material with no perforations so it creates a vapor barrier that can be useful in applications where you are working in high humidity / high hydrostatic pressure areas located between the southern tip of Texas and the Florida-Georgia border on the Atlantic Ocean and you have a stucco structure; or you are installing in sub grade locations in any area of the country (basements/underground rooms); or you are installing a radiant barrier in a cathedral ceiling application between the insulation and the ceiling drywall. SCIF Barrier is an enhanced solid barrier that is used in sensitive areas to prevent the undesired transmission of sensitive data.

Bubble foil insulation incorporates radiant barrier insulation with polyethylene bubble material to create a built in air space so that the material can be used directly against surfaces. Ultra concrete barrier foil (CBF) is a variation that helps to insulate concrete and boost the efficiency of radiant flooring applications.

How can a reflective foil radiant barrier help me save energy?

A radiant barrier can effectively re-direct heat back towards it's source. Therefore, in the summer you want the heat re-directed away from your home but in the winter you want the heat that resides in your house to be trapped there. This provides for a more efficient system year around.

  • During hot summer months a Radiant Barrier can block up to 97% of the sun's radiant heat from being transferred into your structure. Radiant heat accounts for 93% of downward heat transfer into the home.
  • During the winter Radiant Barrier keeps heat from escaping your home or business by reflecting 97% of your homes radiant heat back in, therefore requiring less work by your furnace. Radiant heat accounts for 50-75% of upward heat transfer from your home to the outdoors.
  • A Radiant Barrier will work with mass insulation such as fiberglass and cellulose to increase your bulding's overall resistance to heat transfer.

What is the R-Value of EcoFoil?

R-Value indicates resistance to heat loss, and measures the ability of a mass insulation (fiberglass or cellulose) to slow down heat flow through it. R-Values tell how well a product absorbs and holds heat energy, not how well it redirects it.

All materials have three separate R-Values depending on the direction of the primary heat source. Most insulation manufacturers do not provide all three values when labeling their products. Below we have included the stand-alone R-Value for each product as well as the average application’s R-Value for each product. Keeping in mind the larger the mass, the higher the R-Value. *Mass includes air spaces which we recommend to be at least ¾”.

How well does EcoFoil radiant barrier or bubble foil insulation work compared to fiberglass?

Reflective insulation will stop 97% of radiant heat, which is often overlooked and misunderstood mainly because R-Values do not take it into account. However, radiant heat transfer is responsible for up to 75% of total building building heat loss up through the roof, and 93% of heat that is gained from outdoors into the attic through the roof’s surface. Traditional insulation products such as fiberglass, cellulose and EPS foam board are effective in reducing convective and conductive heat transfer, but do very little to prevent radiant heat transfer. Radiant heat energy can either be absorbed or reflected. (Learn more about the different types of heat transfer here.)

Reflective insulation is very easy to work with. For most applications the only tool requirements are scissors and a staple gun. There are certain applications in which staples will not work but Super 77 Adhesive Spray will. All standard applications are easy Do-It-Yourself projects where you and one other person can complete the entire job in one weekend.

Traditional insulation products often require that you wear safety masks and gloves during insulation due to the actual fiberglass or off-gassing. Reflective insulation does have limited off-gassing, but at a much lower percentage and much safer level.

Does radiant barrier keep areas cool also?

Radiant barrier does not necessarily cool an area, but it keeps the area from getting hot. Our manufacturer conducted the following interesting experiment:

A bag of ice was placed inside each of three boxes. Each box contained a different form of insulation; fiberglass, foam and foil. The melting rate was recorded during the experiment. In the boxes insulated with fiberglass and foam, the bags of ice took 24 hours to melt whereas the bag of ice placed in the box lined with foil took four days to melt. This test clearly shows that the high R-Value does not necessarily equal a better insulator.

Will reflective insulation prevent condensation?

Reflective insulation is an excellent solution to condensation problems in basements or metal buildings. The thermal break provided by the air space prevents warm, moist air inside a building from interacting with cold air on the same surface. When installed correctly, with secure seams, condensation will not occur on the surface of the reflective insulation.  Note that reflective foil should not be used in attic installations where air flow is crucial – in attics the correct choice for radiant heat barrier is perforated radiant barrier.

I already have fiberglass or blown in insulation in my attic. Do I need a Radiant Barrier?

Fiberglass and cellulose insulation work by slowing down heat transfer from one source to another. That's why the thicknesses of that insulation is crucial for performance. Also, fiberglass and cellulose only resist heat transfer, they don't block or reflect it so it eventually escapes through. Our perforated radiant barrier can be installed over top of existing attic insulation to form a reflective cover to enhance other mass forms of attic insulation.

My attic is already well ventilated. Do I still need a Radiant Barrier?

Radiant heat travels in the form of invisible waves until it is absorbed or reflected by a solid surface. Very little radiant heat is removed by the movement of air through your attic. Reflective insulation provides the extra element of protection against radiant heat that ventilation cannot provide.

How can radiant barrier help improve the energy efficiency of my HVAC system?

Installing radiant barrier in your home's attic is the best way to reduce the workload of your HVAC system by nearly eliminating the radiant heat transfer in your attic space. You can also use reflective foil insulation to wrap duct work and reduce energy loss as heated and cooled air is moved from your hvac unit to your home's vents. We recommend easy to install EcoFoil R8 Duct Wrap Insulation to insulate exposed HVAC duct work.

How much tape will I need for my reflective foil installation?

As a general rule, we recommend one roll of tape for each roll of reflective insulation purchased. However it is important to allow for tape overlap, scrap, etc. Rolls of tape are all lengths of 150’ but are available in two widths; 2” and 3”. The 2” roll is more than adequate to cover the seams. The 3” roll is more commonly used for large applications in which you are in a hurry and are not able to spend the extra time to line the tape up with the seams.

Rolls of tape are also available for different applications.

How does reflective foil insulate if it is so thin?

It's a common misconception that all insulation must be thick to perform well. A mass insulation will always have a higher R-value than a thinner insulation due to density, but R-value does not measure all types of heat transfer. Mass has little affect on radiant heat transfer, it is only efficiently blocked through reflection, for this type of heat transfer a thinner reflective material can easily provide better thermal performance than a thicker non-reflective product with a higher R-value.

Does radiant barrier tear easily?

EcoFoil is produced with linear-low density polyethylene, with very high tensile strength and puncture resistance. When handled properly, it is very difficult to tear the material and it is impossible to tear with your bare hands. The many layers of polyethylene add to the strength of the product and will resist tearing at the screw holes.

Will the materials in reflective foil degrade or break down?

Reflective insulation is made from polyethylene and aluminum. Both of these materials are very environmentally stable and do not biodegrade quickly.

What is the warranty for EcoFoil?

EcoFoil carries a 10-year limited warranty against any material defects. Material defects include de-lamination, surface imperfection, foil corrosion and air retention. Any defect in material or workmanship is covered by the EcoFoil warranty.

Will dust affect the performance of the radiant barrier?

Layers of dust do have an effect on the material’s ability to reflect radiant energy. Scientific testing has determined that the actual reduction in reflectivity ranges from 7% to 18% reductions in reflectivity over 10 to 25 years.

Are foil radiant barriers the same as standard household aluminum foil?

Standard aluminum foil (i.e. Reynolds Wrap) is not the same as a reflective foil radiant barrier. Standard household aluminum foil is a very thin sheet of aluminum mixed with other alloys that will oxidize over time, and has virtually no tear-resistance. Radiant barrier foil has a multi-layer structure and is reinforced with a woven scrim that provides outstanding tear and tensile strength. Radiant barrier foil also contains a much higher aluminum content for greater reflectivity and is coated for durability and corrosion resistance.

Will the radiant barrier make my metal hotter than without?

The heat energy that the metal receives comes directly from the sun. No new energy is being created. Only existing energy which has already been absorbed by the metal and is reflected back toward the source.

The same is true for under rafter applications. The radiant barrier will not make your shingles hotter nor will it damage your shingles.   A study performed by RIMA shows that only nominal appreciative heat gain was measured on a rooftop over radiant barrier.  Read the study.

What is the major benefit to adding reflective insulation to a metal building?

Insulation provides increased comfort, energy savings, condensation control, light reflectivity and noise reduction. In a building or warehouse that is not heated or air-conditioned: it is necessary to insulate in order to avoid heat gain in the summer as well as condensation problems inside the building.  The fact that the warehouse is not air-conditioned is even more reason to install a radiant barrier.

Do you have questions not covered here? Please call one of our product experts today at 888-349-3645 and they will be happy to assist you.