My metal roof was red, hot, and desperately needed painting. After spending some time inspecting the roof, I quickly realized how incredibly hot the red paint became even on a modestly hot spring afternoon. Why repaint the roof red since it gets so hot? I thought there must be a better solution so I started investigating roof paints. Fortunately, I wasn’t the only one wondering if a lighter-color roof would reduce heat gain inside the attic and save energy. Also, I quickly learned a lot about “reflective” paints, radiant heat, and the best ways to insulate the attic to reduce cooling and heating costs.
One research article I found informative and one I recommend reading is, Cool Roofs For Hot Climates by Dan Parker, a senior research scientist with the Florida Solar Energy Center (2003). The following is from the article:
Reflective roofs work because they stop the rooftop heat before it ever gets going. The sun’s rays hit the roof at the speed of light, and at the speed of light they bounce back into space. White or light-colored materials work best, but some new dark pigments reflect enough invisible infrared radiation to reject a lot of solar energy. And whether you’re applying tile, metal, membranes, or even asphalt shingles, choosing a more reflective version seldom adds cost.
The figure below graphically depicts the best solution for energy efficiency is a reflective white metal roof:
After reading this article and numerous others, I painted my metal roof with Kool Seal® Premium White Elastomeric Roof Coating which I purchased at the local hardware store (ACE Hardward has it here in Richmond, VA).
Additional Metal Roof Information
Roof Costs and Energy Savings: According to the Metal Roofing Alliance, white-painted metal roofing has the highest solar reflectance value of any roofing product available and can save you up to 40% of your annual energy bills.
According to statistics from McGraw-Hill Construction Research and Analytics®, the number of homes with metal roofs has more than tripled over the past decade, moving metal from 3% of the overall U.S. market to 10%.
Some homeowners’ insurance programs allow discounts for homeowners with specific weather-resistant metal roofing products. Contact your insurance agent to determine if your home qualifies.
Photo taken after the 1991 Oakland, California firestorm. Burning embers destroyed all of the homes in the neighborhood, except the masonry home that was roofed with Stone-Coated Steel Roofing. While all of the neighbors fought (without success) to save their homes by watering down their asphalt roofs, burning embers did not ignite the steel roof. The house with the steel roof survived while all others around it were destroyed. (SOURCE: Metal Roofing Alliance: Lower Your Insurance with Weather-Resistant Metal Roofing)
Kool Seal® Premium White Elastomeric Roof Coating
FEATURES AND BENEFITS
(SOURCE: Provided by the manufacturer, see product description, surface prep, etc. here – PDF)
- Energy saving up to 35%
- Reflects 90%+ of the sun’s rays
- Designed to be durable in any climate
- Higher solids for better coverage
- Forms a thick rubber-like blanket of protection
- Expands and contracts – clings to your roof in all temperatures
- Protects against moisture
- Cured elastomeric film is mildew and algae resistant
- Helps to absorb sound
- Environmentally compliant
- Soap and water cleanup – while wet
Energy Efficient Roofing Video by Tod Miller
Other Useful Articles Pertaining to White Roofs:
- Metal Roof Retrofit on a Hurricane Damaged Home by: Dave Chasar, PE. A before/after energy comparison of shingle roof verses white metal roof replacement; includes monitored data collected at the home over several years.
- Metal Roofing Alliance – www.metalroofing.com
- The Cool Metal Roofing Coalition – www.CoolMetalRoofing.com
- Energy Star – www.EnergyStar.com