Normally, regardless of roofing material (tile, shake, modified bitumen, asphalt, metal, foam, etc.) the last layer applied is the coating. The coating applied can range from a number of different materials including rock, granules, cement, polymers, asphalt, polyurethane, aluminum, acrylic, and more. The coating is usually elastomeric (very elastic) and extremely durable. Because the coating is elastomeric, it can handle debris, branches, and hailstones because it will morph back to the original shape after it takes the impact.
Why coat the roof though?
It is nice enough to have a layer of protection, but most people are not entirely sure why they need coating anyway. After all, you have a roof that is usually made up of at least three layers (an adhesive, the roof material, insulation, and a waterproof membrane) so should that not be tough enough to absorb impact? There are actually three reasons:
- Prevent degradation – The main reason you use a coating is to protect whatever material you have used. This prevents it against general wear and tear and the weather. For example, asphalt shingles are treated with granules to protect it from UV light, a foam roof is treated with a tough rubberized coating…in short, if you want your roof to last longer, then you will need to apply coating.
- Improve energy efficiency – Aside from keeping the roof in better condition, it also reflects heat. That means residential and commercial property owners can enjoy a roof that not only lasts longer, but also offers savings on energy costs.
- Reduce urban heat islands –. Because urban areas have such a dense concentration of masonry, metal, asphalt, and concrete, they often absorb the heat and retain it for longer periods. This means that a city can feel upwards of 10 -15 degrees warmer than the surrounding countryside. Applying reflective coating in urban areas can help relieve part of this problem.
Coating and re-coating is the key to a healthy roof
When you hear professional roofers discuss roof maintenance, they are generally talking about re-coating (refreshing the coating) on the roofing materials. Because coatings take the beating so that the roof does not have to, applying a new layer occasionally will often help save on energy costs, protect your roof from damage, and prolong its life.