Saving money and the environment come into play by painting your roof white. The color white reflects heat, which causes less warmth to be absorbed by the house. Thus, you should have lower energy bills on hotter days.
Aside from saving on energy bills, there is the greater issue of doing your part to combat global warming. Steven Chu, former U.S. Secretary of Energy and a Nobel prize-winning scientist said that painting roofs white or another light color would help reduce global warming by reflecting sunlight into space. This would be like removing every vehicle from the planet for 11 years.
Other than in commercial applications, it's not as common for homeowners to paint roofs white. Here are useful tips on how it can be done.
Types of Roofs That Can Be Painted
Let's assume you have a composite or asphalt shingle roof, which is increasing in demand as reported by the Global Asphalt Shingles Market due to its affordability, style, and quality. Asphalt shingles can also be painted white, which costs less than replacing the roof and is more sustainable.
How Big Is Your Roof?
White roof coating is pricey and typically purchased by mail order. Instead of square footage, roofers use a term called "squares." A square equals 100 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 Should You Choose?
Another consideration is that heat-reflecting roof paint is not widely available. A highly-rated option is the Henry 287 Solar-Flex White Roof Coating made with an elastomeric latex that gives your roof up to seven years of protection with just one application. Another supplier is Melbourne, Florida-based HyTech, with its Insul Cool-Coat #2000 that is lower in price, though it may require more effort and paint as they recommend two applications.
Calculating Quantity and Price of Materials
Let's go with that 2,000 square foot calculation we provided earlier. For the Henry paint, you would need to apply about 14 gallons, which would cost you in the range of $1,000 for one application.
Do White Roofs Really Save Energy?
There are mixed opinions on whether painting your roof white will save energy and money. White roofs reflect heat and cool homes in the summer but in the winter they drive up heating bills, which is not helpful for homes in northern climates. Thus, solar panels that create energy are the preferable option. There is accumulating worldwide evidence in support of white roofs. Keith Oleson of the National Center for Atmospheric Research in Boulder claims that if every roof in large cities around the world was painted white, thereby raising their reflectivity, it would limit the urban heat island effect by a third. Thus, white roofs have more of an advantage in warmer climates and should factor into your decision.