Do Roof Coatings Work?

Function

• You need to evaluate your roof and a coating the same way you would if you were installing shingles or any other type of roofing material. For example, a coating is unlikely to perform well if your roof is in poor condition, or if the surface isn't prepared in accordance with the manufacturer's instructions. You also need to select a coating that's designed to meet your intended purpose. Some coatings help keep a roof cool to reduce a homeowner's cooling costs in summer, and others protect a roof from water damage.

Energy Efficiency

• A reflective roof coating reflects sunlight and radiates absorbed heat back into the atmosphere instead of drawing it into a home. However, the effectiveness of a reflective coating depends on how hot your climate is, according to the Service Magic contractors’ website. You could save up to 70 percent in cooling costs if you live in an area where it's sunny and hot most of the year. The Service Magic site indicates you may only recoup 20 percent in energy savings if you live in a cooler climate.

Product vs. Purpose

• A product that contains urethane is usually suitable for waterproofing a roof. However, some homeowners may assume that reflective coatings and similar products will seal leaks, because the coatings are usually thick. The FacilitiesNet website notes that reflective-coating manufacturers state in their instructions that their products don't seal leaks. Furthermore, manufacturers usually recommend that users fix leaks and other roofing problems before applying their reflective coating, according to FacilitiesNet.

Surface Preparation

• The surface to which you apply a roof coating also impacts its effectiveness. Coatings generally adhere well to concrete roof decks, but the grainy surface of shingles and other roofing materials makes it difficult to apply a coating properly. Surface preparation is a key step in getting a coating to last a long time. FacilitiesNet indicates that loose roofing materials and coatings should be scraped off before applying a new coating. Some manufacturers recommend applying a primer to a roof before applying their coating so the product adheres to the surface better.