Reflective roofs are terrific at repelling solar heat during hot weather. I have coated a couple of roofs during hot weather and you can notice an immediate difference in comfort. Cover up or wear sunscreen when you apply it because the reflected heat gets intense. If we want to stay cool while avoiding high electricity costs, a cool roof is necessary to have.
What Building Benefits from a Cool Roof?
Mobile homes and other buildings with coatable roofs can benefit from installing a cool roof. All flat roofs should adopt this strategy immediately. The payback takes only 2 to 5 years and the return on investment is 20 to 50 percent per year. Where else can you get that kind of performance for your money?
Types of Cool Roofs
There are a variety of roof coatings that can repel 75% or more of the solar heat. These are white elastomeric coatings. There is a variety of quality and cost with these coatings depending on the amount of solids in the mix. If you want the longest lasting coating, you may have to buy from a commercial roofing wholesaler. If you coat an asphalt roof, you may need to apply a primer before applying the elastomeric coating. Look for an ENERGY STAR logo on the coating for best results.
With a mobile home, you can blow fiberglass into the roof cavity before applying the coating. Fiberglass blowing insulation and the roof coating would cost you around $1.50 per square foot for the materials. Professional installation would run another $1.50 per square foot. If you want a really comfortable mobile home, add an inch of polyurethane foam on the roof after installing the fiberglass. Combining roof coating and roof-cavity insulation would reduce your air conditioning cost by 15 to 25 percent.
Rubber roof caps also help. While you can purchase black rubber roof caps, a white rubber membrane is much better as it not only provides protection and insulation, but it increases the roof’s reflectivity which helps cool the home.
Metal insulated roofing is another alternative that can help reduce the need for AC cooling. Just make sure to choose a light colored metal roofing.
Incidentally, I would recommend against installing powered attic ventilators. Powered attic ventilators will keep the attic cooler but they won’t reduce your electricity costs because they use a lot of electricity.
For more information on what you can do for a cool roof, see our books: Homeowners Handbook to Energy Efficiency, Your Home Cooling Energy Guide, and Your Mobile Home.