Is a Radiant Barrier Right for Your Home?
Radiant barrier is a great addition to attic insulation. Properly insulating your home is a great way to improve energy efficiency and comfort especially if you add a attic stairs cover. With all the different products available how do you know which is right for you? Here is some information to help you decide if installing a radiant barrier is a good idea for your home.
"Remember, with all properly installed insulation, the payback is certain...if you give it enough time. If you are moving in a year, only go with the basics that will improve the sale of your home."
What is Radiant Barrier?
Radiant barriers are made of aluminum and designed to reflect radiant heat from the sun. When installed properly, radiant barriers can reflect up to 95% of the radiant heat off the attic. The best way I have seen to describe this effect is it’s like putting your home or office under a shade tree.
"Installing a radiant barrier is like putting a shade tree over your attic."
There are many brands of radiant barrier available. Here are some tips to make sure you are using a good product:
Non-laminated radiant barrier - In a lamination process, the foil is either simply glued on or heat laminated to the plastic lining. Both of these processes will eventually fail. With some products you can peel the foil off the plastic right out of the box, with others you have to leave it in the attic for several years before you can easily peel it off.
Protective coating installed - Without this protection, aluminum will oxidize loosing its ability to reflect heat. As the surface of the foil begins to oxidize, it turns cloudy. If it continues and oxidizes all the way through, it will eventually turn clear.
Passes newest fire codes - make sure the radiant barrier passes all of the current codes including the ASTM E84 fire test under the new mounting method (ASTM 2599).
Radiant barrier benefits
The benefits of radiant barriers are both monetary as well as increased comfort. If your home or office are in the direct sun your roof radiates solar-generated heat to the insulation below it. The insulation absorbs the heat and gradually transfers it to the material it touches, principally, the drywall ceiling. This heat transfer makes your home less comfortable and can cause your air conditioner to run longer and consume more energy. A properly installed radiant barrier can block 95 percent of the heat radiated down by the roof so it can’t reach the insulation.
Roof-radiated heat also warms ductwork or mechanical equipment (air handler) found in your attic. The proportion of the total heat gain the ductwork represents, compared to heat gain to the interior of the house, varies depending on the amount of attic and duct insulation you have.
Should I apply radiant barrier to the attic floor?
According to the Department of Energy installing radiant barrier on the floor of the attic can cause problems. It may be an easier way to install radiant barrier but it can trap moisture between itself and the attic floor and cause the insulation to become damp. Damp Insulation may support mold growth and eventually will lose some of its R Value. If you decide to apply a radiant barrier to the floor of your attic make sure you air seal the attic floor with a closed cell spray foam prior to installation.
Will a radiant barrier damage my shingles?
I have had this question asked many times and I see no evidence that a radiant barrier damages shingles. The Florida Solar Energy Center has measured the temperatures of roof shingles above attic radiant barriers on hot, sunny summer days. Depending on the color of the shingles, their peak temperatures are only 2-5° F higher than the temperature of shingles under the same conditions without a radiant barrier. Since roofing materials are manufactured to withstand the high temperatures to which they are frequently exposed. A 2-5° F increase in peak temperatures that normally reach 160-190° F should have no adverse affect.
Radiant Barrier Cost
Since all buildings and there uses are different, this is a very difficult question to answer but according to research done by the Florida Solar Energy Center, you could save between 8-12% on annual cooling costs. If this is true, the cost of installing a radiant barrier is irrelevant given you stay in your home long enough to recoup your investment. The benefits of a radiant barrier extend beyond monetary and should make your building more comfortable as well. It is also a good idea to make sure the attic is properly ventilated. Installing a solar attic fan is a great way to save money and may qualify for a 30% tax credit.