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Frequently Asked Questions:


How does radiant barrier foil insulation work?

Radiant barrier foil insulation is unlike mass insulation that merely slows down or resists heat transfer. A radiant barrier BLOCKS radiant heat. Heat always moves to colder areas by natural law - the problem is how to keep the heat in the winter and how to keep it out in the summer. There are three ways in which heat moves from warm spaces to cold spaces: CONDUCTION is the direct heat flow through a solid object such as a wall or a ceiling. CONVECTION is heat movement through air, occurring when air is warmed. The warm expands, becoming less dense and rising. RADIATION is the movement of heat rays across air spaces from one warm object to a cooler object. The heat we feel from a wood stove or a quartz space heater is radiant heat. ALL OBJECTS AND BODIES GIVE OFF RADIANT HEAT.

Radiant barriers BLOCK radiant heat by reflecting it back towards the direction it came as well as REDUCE convective heat by acting as a blockage against convective air flow. With a radiant barrier properly installed, you can significantly reduce the amount of heat that common insulation materials are designed to slow down thereby maximizing the efficiency of common insulation materials making your living space more comfortable and reducing your overall energy utility costs.


Can a radiant barrier keep me warmer in the winter?

Just like wrapping a baked potato in aluminum foil keeps a potato warm longer by holding the heat in, covering your attic insulation with radiant barrier holds heat in the house. Another analogy would be that radiant barrier foil insulation in the winter works just like a space blanket, which, although very thin and lightweight, holds your body heat in. A thin space blanket can keep you warmer than several heavy wool blankets.


What is the "R" value of a radiant barrier?

Radiant barriers do not absorb heat like mass insulation (fiberglass, cellulose, foam, etc). Instead, our radiant barriers, with their highly reflective surfaces, reflect 97% of the radiant heat that hits it and therefore, have no R-value rating.

Installing a radiant barrier between the heat source (sun) and an existing R-Value rated insulation will improve the effectiveness of the R-Value rated insulation. Why? Because only 3% of the heat is now hitting the R-Value rated mass insulation giving it more time to absoradiant barrier heat before becoming saturated and passing the heat into your living spaces.


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

o. 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 radiant barrier products are (unperforated), doesn't qualify them as underlayments.


How important is venting in my attic ?

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.


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. 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%.


If I have ducts in my attic, above my insulation, should I cover them with radiant barrier ?

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! radiant barrier 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.


What other uses are there for your radiant barriers ?

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.


Do I have to have other insulation in my attic for a radiant barrier to be effective?

No. Radiant barrier foil insulation actually makes your present insulation more effective. Installing a radiant barrier between the heat source (sun) and an existing R-Value rated insulation will improve the effectiveness of the R-Value rated insulation. Why? Because only 3% of the heat is now hitting the R-Value rated mass insulation giving it more time to absoradiant barrier heat before becoming saturated and passing the heat into your living spaces.


I already have plenty of insulation in my attic. Do I really need a radiant barrier?

Regardless of how much insulation you have in your attic, adding radiant barrier foil insulation will save on your heating and cooling expense, and keep you much more comfortable. Energy savings for heating and cooling can vary from 10% to 25% depending on a number of factors, including climate, building configuration, materials used, site, family size and lifestyle.


Will my roof shingles get hotter and deteriorate with a radiant barrier in my attic?

A radiant barrier may cause an increase in shingle temperature between 2-5 degrees Fahrenheit on a hot summer day. Given that shingle temperature at that time is in the range of 160-190 degrees, this increase is negligible and does not accelerate shingle degradation.

Radiant barrier foil insulation has been used extensively in the south, showing negligible differences in roof temperatures, as confirmed by field tests.


Will the radiant barrier aluminum corrode over time and lose its effectiveness?

As long as radiant barriers products are properly installed and not exposed to outdoor weather conditions, they are expected to last the lifetime of the building structure in which they are installed.


How much money can I expect to save on my utility bills if I install a radiant barrier in my attic?

Although radiant barriers BLOCK 97% of radiant heat, your utility bills savings will vary because there are other forms of heat flow in a building that contribute to the total heating load. Data varies by region.

Based on study performed by the Tennessee Value Authority, savings averaged approximately 17%. It consistently showed heat flux reductions compared to the non-radiant barrier test case of about 40% percentt for almost all ambient temperatures and even showed savings (17% percent) during mild temperature and night summer conditions.


Are radiant barrier tested by qualified independent testing agencies or governmental agencies?

The Florida Solar Energy Center at Cape Canaveral has tested radiant barriers in both small scale laboratory and full scale building models. Their results indicate that radiation barriers provide significant resistance to heat transfer. Current tests conducted by the Tennessee Valley Authority and the University of Mississippi support the findings at the Florida Solar Energy Center. Northeastern Illinois University conducted winter tests in residential and commercial structures using infra-red thermograph photography. The photos showed significant resistance to heat transfer over the regular insulation.