It's the big topic, the idea du jour. Supposedly, painting your roof white has many benefits. Because the color white reflects heat, less heat is absorbed by the house. Thus, lower energy bills.
Not only that, you get to save the planet. Steven Chu, the U.S. Secretary of Energy and a Nobel prize-winning scientist, has said that painting roofs white or another light color would help to reduce global warming by reflecting sunlight back into space—it would be like removing every vehicle from the planet for 11 years.
The thing that no one discusses is how to paint your roof. Other than in commercial applications, few people have actually gone out and painted their roof.
Types That Can Be Painted
First, let's assume that you have a composite or asphalt shingle roof. It is estimated that upwards of 80% to 90% of homes in North America have composite roofs. The number is flexible, depending on whether you ask a roofing trade group or an objective observer. But I would say that the number sounds pretty accurate. Just look out your window if you don't believe me.
How Big is Your Roof?
Not just an idle question—a critical question. As you will see in a moment, roof paint is blindingly expensive. And it typically comes only by mail-order.
Instead of square footage, roofers use a term called squares. A square equals one hundred square feet.
For a house measuring 30 by 50 feet (on the ground), you have approximately 15 ground-level roofing squares. Translating this to a roof-level figure will give you 20 squares of roofing shingles. The number is bigger because of the roof pitch, or slope. Twenty squares are 2,000 square feet of roofing shingles you need to paint.
Which Paint to Choose?
Now, this is where it gets tough. Sources of heat-reflecting roof paint are, at this time, limited. The most active supplier of this type of paint is HyperSeal with their Hyperglass Cool Top Coat. Another supplier is Melbourne, Florida-based HyTech, with their Insul Cool-Coat #2000.
Calculating Quantity and Price of Materials
Let's go with that 2,000 square foot calculation we came up with earlier.
For the Hyperseal paint, you would need to apply about 14 gallons for the first coat. At current prices, this would cost you $466, shipping not included. Since you need to apply two coats, let's assume that you're using half that amount—7 gallons—for the second coat—final price: $735, again no shipping.
HyTech paint is a bit cheaper. At the very low end, assuming a spread rate of 100 square feet per gallon, your entire price tag would be $525 for both coats.