The How, What, and Why about Radiant Barrier insulation
Radiant Barrier Paint Additives / Spray Coatings
As the leading manufacturer for radiant barrier foil and metalized film products, we are seen as experts in the industry, not just with homeowners, but even professional contractors and installers. In fact, one reason for creating this blog was to help educate the public and answer some common questions.
Recently, we’ve been fielding questions about a different type of reflective technology: low emissive ‘radiant barrier’ paints and coatings. Lately, questions like: “Does radiant barrier paint work?” “How efficient is radiant barrier paint?” “Are the chemicals in those paints and coatings safe?” and “Is radiant barrier paint a scam?” have become so common that it’s scary.
To better educate the consumer, our technical team has come up with the top 5 reasons to choose a real sheet radiant barrier, like radiant barrier foil or metalized film, over one of these radiant barrier paints or spray coatings that are frequently advertized and heavily marketed.
1. Radiant Barrier Paints / Coatings Are Not Real ‘Radiant Barriers’
According to the ASTM definitions of a “radiant barrier” and the FTC definitions of “home insulation”, the paint products on the market qualify as neither. The most efficient of these paints / sprays are called “interior radiant control coatings” or IRCCs, but some so-called radiant barrier paint products do not even meet the efficiency requirement to be called an IRCC. So how does this affect the consumer? Simply stated, the radiant barrier paint additive or spray coating products do not meet the same building requirements as radiant barrier and do not qualify for the same energy efficiency credits.
“Currently, EPA does not label paints and coatings for the inside of roof decks (or attic) in the insulation program because paints and coatings do not meet the Federal Trade Commission (FTC) definition of ‘home insulation.’” -ENERGY STAR
Because Energy Star uses the same requirements as the FTC for insulation and energy efficiency, these radiant barrier paints / spray coatings are not included in the radiant barrier requirement for Energy Star homes. In some cases, there are tax credits or energy credits available for radiant barriers, like recent IRS tax credits and energy credits through various cities, municipalities, and even utility companies, for which radiant barrier paints will not qualify. If you are looking to qualify for rebates like these, or have building requirements to meet, you need to be using a true radiant barrier foil.
2. Radiant Barrier Paint / Spray Is Less Efficient
According to a RIMA International study, an association made of manufacturers of radiant barrier, reflective insulation and radiant barrier paint additives / spray coatings, the radiant barrier paint products on the market have a wide range in efficiency and energy savings. Some of these paints only block out only 10%-14% of the radiant heat, and some block up to 64%-85% of the radiant heat. All true radiant barriers start off at a minimum of 90%, and our Super R radiant barrier blocks 95%. Even the most expensive paints with higher efficiency, may cover a smaller area, further reducing the efficiency. Radiant barrier paint is typically sprayed directly to the underside of the roof decking, leaving the roof rafters uncovered. There is nothing to stop these wood rafters from emitting the radiant heat directly into the attic. Assuming the rafters are 1.5″ wide and are spaced 24″ on center, then even the best, most expensive radiant barrier paints / sprays only block 59%-78%.
Additionally, the radiant barrier paints are not always sprayed consistently or evenly across the roof decking. It is easy to see areas that have a thinner coating because the wood can often be seen through. There have even been cases where installers realize at the last minute that they didn’t bring enough paint for the whole roof, and do a thinner coat or dilute the radiant barrier paint with water to stretch it further. Since foil radiant barrier is installed across the bottom of the roof rafters, and is made with a sheet of pure aluminum, Super R radiant barrier will always block 95%.
|Product||Manufacturer||% Radiant Heat Block||% Heat Block – Adjusted for Rafters|
|HeatShield R-20||Kwik Co||10||10|
|Radiosity 3000||Green Building Supply||11||11|
|Formula A Barrier Coat #85||Hy-Tech||34||32|
|Therma-Guard Silver||United Community Services of America||43||40|
|Heat Bloc-Ultra||STS Coatings||80||74|
|LoMitt-II Max||Solec-Solar Energy Corp.||85||78|
|Super R Diamond Radiant Barrier||Innovative Insulation Inc||95||95|
|Super R Plus Radiant Barrier||Innovative Insulation Inc||95||95|
*These calculations are based on emittance values published by RIMA International
3. Your Radiant Barrier Paint May Not Last
When dirty, older wood surface (like a roof deck) is painted, nearly any paint manufacturer or professional contractor know that the surface should be cleaned, sanded, primed and coated with multiple coats of paint. These steps are Painting 101 to ensure that the paint adheres to the surface and doesn’t peel or fade. Yet these basics are completely ignored by most radiant barrier paint / spray installers.
If the radiant barrier paint coating is sprayed to the roof decking without cleaning off the dirt and debris, and sanding down the surface, painting over dirt and debris can result in poor adhesion and may lead to an uneven coating. This is the primary reason that paints crack, chip, peel and fade after just a few years time. Applying a primer over the clean, smooth surface is essential because it not only increases the durability of the paint, but provides a smoother surface to improve the reflection and overall performance of the paint. Finally, when you need a consistent, even covering over wood, which is certainly what you’re looking for in a radiant barrier paint / spray, then multiple coats of paint are often necessary.
4. Radiant Barrier Paint May Contain Hazardous or Toxic Chemicals
For chemically sensitive or hypersensitive homeowners, a radiant barrier paint product may not be an option. Homeowners who are not chemically sensitive but are still concerned about a toxic or hazardous product being sprayed right over their heads, right near their ventilation system, should look closely at the product’s MSDS sheet. Many of these paints contain chemicals that can prove hazardous when in contact with the skin, eyes, nose and throat.
Due to some of the hazardous chemicals contained in radiant barrier paint products, manufacturers recommend that the installer wear personal protection like an impervious protective suit, a pair of ANSI approved safety glasses, and a NIOSH/MSHA approved respirator. In fact, RIMA-International has issued a safety statement saying that these products may “contain hazardous chemicals or emit fumes, which can enter the body through inhalation, skin absorption, or injection into the eyes, nose or throat.” Before use, consult the manufacturer’s MSDS sheet.
5. Radiant Barrier Paint / Spray Coatings Are Difficult to Do It Yourself
Unlike the sheets or rolls of real radiant barrier foil or metalized films, the radiant barrier paint / spray coatings have special installation requirements. ASTM C 1321 describes special procedures that need to be taken to ensure the products are applied properly and that the product does not damage the surface to which it is being applied.
Radiant barrier paint additives / spray coatings not only require special protective clothing, but may also require the use of special equipment and tools to meet safety requirements. ASTM C1321 states:
- All pressure pots must be equipped with an air driven agitator
- Vent baffles must be used in areas where the paint compromises the ventilation
- OSHA approved fans must be used to expel the hazardous fumes in poorly ventilated areas
- All electrical wiring must be protected to ensure that the paint doesn’t contact the electrical wiring system
A sheet radiant barrier foil or metalized film, in addition to being significantly more efficient, requires no unique tools or equipment. The foil radiant barrier can simply be cut with a standard utility knife and applied with a standard staple gun, meaning it can be installed easier and at a lower cost.
There are no hazardous chemicals or fumes from a radiant barrier foil, making it safe for the chemically sensitive, and using a variety of installation methods, radiant barrier foil can cover the entire attic, forming a continuous and consistent 95% heat blocking radiant barrier.