Roof coatings can prolong a roof’s useful life, minimize the effect of UV light and control energy costs

TOP-LEVEL Considerations

Conditions on the roof of a building can be severe. During summer months, temperatures can reach 170 degrees on a low-slope black asphalt roof, and they can drop to -40 degrees during the winter in some northern regions. Harsh conditions like this quickly break down many roof materials.

Very popular Tar and Gravel (built up) roofs attract extreme heat causing them to break down more quickly Example of the cracks caused by “Heat Stress”Once this style of roof has been cleaned, repaired and coated it no longer suffers the stress and will last for many more years.

This is one reason that relatively inexpensive and replaceable roofs are so common. Some people maintain that all black or dark coloured surfaces, such as asphalt pavements and exposed black roofing materials, are contributors to a heat-island effect, by which much of the heat generated by absorbing the sun’s ultraviolet (UV) radiation transfers to the building interior. In cooler climates, this problem can be minor. But in areas with warmer temperatures, this problem increases the demand for power, as the air-conditioning systems labour to maintain a comfortable working climate. Maintenance managers have a variety of roof coatings options to choose from in an effort to prolong a roof’s performance life, minimize the effect of UV light on roofs and interior operations, and help managers control energy costs.

The protective layer

UV radiation and visible light from the sun repeatedly impinge upon the outermost surface layers of roofing systems, accelerating oxidation and chemically degrading the system and causing it to become brittle. As if these challenges weren’t enough, rain, snow, sleet and hail further compound roof destruction through erosion, expansion and contraction forces, and mechanical impact. Applying a roof coating on top of a conventional roofing system can act as a shield against these forces of nature. This protective coating can increase a roof’s expected life cycle and improve a building’s energy efficiency. It can help roofs resist baking by the sun’s radiation, as well as chemical attack, and it can prevent the formation of small cracks that otherwise collect dirt and chemicals and grow into larger cracks. The optical properties of protective coatings determine how well a roof reflects sunlight. Reflecting sunlight has an immediate effect; namely, lowering roof temperatures. And since chemical reactions often increase exponentially with temperature, a roof with a good reflective coating will not deteriorate as quickly as one with no coating and, hence, is exposed to higher daily temperatures. The underlying roof might provide excellent moisture resistance in the event of rain, but a coating often is essential to protect this waterproofing agent against other forms of erosion and degradation.

Product options

Manufacturers of roof coatings offer a variety of solutions to these challenges in the form of water-based, solvent-based or hybrid roof-restoration systems. These lower-cost, high-quality maintenance systems provide maintenance and engineering managers with solutions to their needs while avoiding or delaying the higher cost of roof replacement. Roof-restoration systems minimize disruption to businesses and offer environmentally friendly solutions that are safe and can be cold-applied. They also might provide a higher rate of return on investment via energy savings through the use of reflective coatings. High reflectance coatings can reduce thermal shock, membrane fatigue and heating or cooling loads, which alone can lower building energy costs, especially when combined with other energy saving measures.