Are Urethane Roof Coatings Effective?

Liquid or Foam

• Urethane is a copolymer emulsion that exists in many forms. Depending on the use, it can be sprayed, brushed or rolled on a roof as a liquid, or applied as a foam that is several inches thick. It forms a seamless coat that is weather, sunlight, chemical and mildew resistant. Many manufacturers have a line of urethane roof coatings that provide various types of coverage and goals.

Standards

• The American Society for Testing and Materials D 6083 sets standards for urethane coatings that allow a consumer to compare the different types. It measures such areas as how long the coating lasts under weather conditions, the ability to seal out moisture, strength and how it performs in the winter. If a manufacturer meets the code's requirements, it is noted on the container.

Uses

• Roof coatings can seal against moisture and weathering, or reflect the sun to provide energy savings, but the same coating cannot do both. If a leak and weather sealant is required, then the Facilities Net website recommends a monolithic waterproof coating, such as a urethane. If the purpose is to save energy, then a reflective surface from a sprayed polyurethane foam is recommended. Urethanes are normally not applied over other roofing products.

Preparation

• Urethane roof coatings are mostly used for industrial and commercial buildings and are generally not found in homes and dwellings, except for apartment complexes with larger, flat roofs. The roof has to be thoroughly cleaned and dry before any urethane coating is applied. Dust, dirt, moisture and other debris will otherwise be trapped under the coating. A simple spray or brush-on coating does not require professional application.