WHICH FLAT ROOF COATING WILL WORK BEST FOR YOUR COMMERCIAL ROOF SYSTEM
As a property manager of a flat roof system, one of the many concerns hanging over your head (literally) is the threat of a leak or roof damage. Restorative coatings can give you the peace of mind in knowing that your roof system will be efficiently protected for years to come. Coatings often avoid the costly hassle of roof replacement by providing additional protection and a decrease in energy costs. The array of available coating options have tripled over the past 25 years. With the advancement in products, the choices have become more complicated. Here is a closer look at the four most popular coating options.
Acrylic – Acrylic coatings are water-based materials that are made of a single component that does not require any additional component mixing. Pros of water-based acrylic coatings include low flammability and potential for toxicity hazards. Unlike most other coating options, acrylic materials come in a variety of colors to match your building’s color scheme. Cons include the requirement of many applied coating layers in the right external temperature for proper curing. There are limitations to when an acrylic coating should be applied – too cold and it will freeze; too hot and it will not set properly. When ponding water is present on roof surfaces for a period of 48 hours or more, acrylic roof coatings can begin to re-emulsify to their liquid state and lose adhesion.
Silicone – Silicone coatings have been in the industry for a long time and are most commonly used to cover and protect spray polyurethane foam (SPF) roofs due to the coating’s permeability. Silicones are also very well-suited for areas with extreme temperature ranges and where UV exposure is more frequent. Silicone coatings provide a slick surface and, once applied, only another layer of silicone coating can be applied as the recoat. One drawback is high dirt pickup of these types of coatings. Therefore, they would not be ideal in highly visible areas where aesthetics are required. Also, silicone coatings have very low abrasion resistance, so they are not the ideal coating for areas of high traffic.
Foam – Spray foam coatings first came on the market in the 1960s and are a popular choice for built-up roofing systems (BUR systems) or single-ply roof systems. This type of coating stands out due to their energy efficiency, long life expectancy, and cost-efficiency. However, one of the most common improper applications of this roof system layer is the inconsistent application of the roof coating, or the application of it at differing levels of thickness across a rooftop. Specialized training is needed to assure the roofing contractor puts down the spray polyurethane foam correctly.
SEBS (Thermoplastic) – SEBS rubber coatings, also known as thermoplastic elastomers were specifically designed as an economical field coating for metal roofs. This coating can also be used on most types of concrete, metal, urethane foam, modified bitumen and non-plasticized single ply membranes. It is a low permeable, wash-off resistant product with superior adhesive capabilities. The low permeability rating enhances algae and fungi resistance and allows for a durable bond on roofs subject to ponding water. Gallagher Construction Group recommends the use of SEBS coatings because of their superior resiliency and the seamless coverage over vertical seams and fasteners. Other benefits include tenacious adhesion, high tensile strength, chemical and UV resistance and low moisture permeability.
The color of the chosen coating can also play an important role in the decision making process, especially in warmer climates. Pigmentation options are often limited which leave the most common colors of white, black and gray because of the superior UV resistance. White can typically reflect over 80% of the UV rays in keeping with the nation’s Energy Star program. Please keep in mind that over time roofs collect dirt, and a white, reflective roof will lose some solar reflectance over time. It’s important to have an annual maintenance program in place with a professional, certified roofer to clean and maintain your roof coating and identify any small issues before they become large and costly ones.