Benefits of Roof Coatings

Roof coatings are applied to low slope roofs on residential, commercial and industrial buildings to extend the life of a roof by preventing water, chemical or physical damage, which saves money for the building owner. Certain roof coatings even provide an extra level of waterproofing protection to help shed water to keep building interiors dry. Also, roof coatings are the most effective and least costly option to help buildings save energy.

Reflective roof coatings reflect visible light and infrared and ultraviolet radiation. This leads to lower roof temperatures, which, in turn, helps reduce cooling costs for buildings with air conditioning units and reduce interior temperatures in buildings with no cooling units. By minimizing cooling costs in warmer climates, peak energy usage is reduced, decreasing the risk of power outages and the strain on the electrical grid.

How Roof Coatings Prevent Tear-Off and Waste

Every building owner will eventually be faced with the decision to completely tear-off an existing roof or to repair it. In fact, 2.5 billion square feet of roofs are either replaced or re-coated each year. Given that roofing materials are the third greatest contributor to waste in landfills, roof coatings are an ideal solution to extend the life of a roof and delay tear-off and waste.

Roof coatings are available with a wide range of properties and consistencies to fit a multitude of purposes. These include:

■ Low viscosity, non-fibered coatings: formulated as penetrating primers and dampproofing coatings.

■ Medium viscosity, fibered and non-fibered coatings and cements: formulated as inter-ply adhesives and top coatings for use on commercial, industrial and residential roofs. Some of these coatings incorporate pigments to reflect the damaging rays of the sun, creating a longer performing and more energy-efficient roof.

■ High viscosity, heavy bodied cements: designed for adhering waterproofing membranes and components and for patching and repairing leaks.

Which are better: solvent, water-based or moisture cure elastomeric coatings? Solvent, water-based and moisture cure coatings each have their advantages. Solvent based tend to be more waterproof, can be used in colder weather, won’t freeze, are less affected by humidity and rain after application and will adhere to certain surfaces, such as TPO, that water-based coatings often will not.

Water based coatings have lower odor, are “breathable” (so are more suitable for masonry), are less prone to “bleed through” or discoloration when applied over asphalt and are generally easier to spray as they don’t change viscosity significantly at different temperatures.

Moisture cure coatings allow solids of up to 100 percent, so the film thickness per applied volume is greater. They are generally low odor and low volatile organic compounds (VOC). The tradeoffs are shorter shelf life and limited adhesion to some surfaces, including TPO and asphalt that require primers. While they won’t freeze, moisture cure coatings will not cure normally when temperatures are below freezing and there is little free moisture in the air.

What is the dew point and why is it important? The dew point is the point at which moisture in the air condenses into liquid water. Many coatings require a dry surface. Surfaces may appear dry but moisture will condense as the coating is applied because the application of coating will often lower the surface temperature of the roof surface at the point of application, causing liquid water droplets to be trapped under or encapsulated in the coating.

What are reflectivity and emissivity and why are they important? Reflectivity is the percentage of solar energy reflected by the coating back into the atmosphere. The remaining energy that is absorbed increases the temperature of the roof surface. Higher reflectivity results in less absorbed energy, which results in less potential heat gain.

Emissivity is a measure of the coatings ability to emit absorbed solar energy as infrared radiation. Higher emissivity will generally result in a cooler