In these times of economic uncertainty, operations and capital improvement budgets are being reduced or eliminated to preserve profitability and retain staff. Although the budgets of commercial facility managers are not exempt from cuts, a leaking or failing roof must be properly addressed to preserve property and protect workers.
But how can facility managers balance short-term budget realities with the need to maintain properties for the long term? Advancements in roofing membranes can help reduce capital costs by restoring rather than replacing roofs. This also helps reduce waste materials headed to landfills. In addition, new lighter-colored roof materials reflect rather than absorb the sun’s radiation, which helps lower roof temperatures and reduce a building’s energy load.
Restore Rather than Reroof
Due to the persistent nature of water, a roof leak can be difficult or almost impossible to solve completely. Roof age, material type, and climate zone all can influence whether a commercial roof can be restored or whether it should be completely removed and replaced—the latter of which is a costly and disruptive solution.
Building owners, facility managers, roofing contractors, and even insurance companies influence the decision to reroof or restore. Each stakeholder seeks a solution that provides the highest protection possible while considering cost. Building owners must maintain acceptable fire ratings given the building type, age, and use. Insurance companies often can dictate roofing solutions as a condition of maintaining coverage. A failed roof can have huge financial ramifications due to property damage or even loss of life.
A growing concern in the roofing industry is the amount of waste that reroofing generates. According to the Sacramento-based California Integrated Waste Management Board, approximately 11 million tons (10 million metric tons) of waste in the form of asphalt roofing shingles are generated in the U.S. each year.
The tear-off singles from reroofing jobs account for 10 million tons (9 million metric tons) of the total waste generated. The remaining 1 million tons (907,000 metric tons) are scrap from manufacturing new shingles. Restoring instead of reroofing helps reduce the amount of waste materials destined to go to landfills by reusing the underlying roof materials rather than removing them.
Operational realities also can influence the decision about whether to reroof or restore. Workload was a factor in the case of a roof project for the Lakeland, Fla.–based Region Center, a commercial complex housing a beverage-bottling plant and the offices for a health care supply recycling company.
Reroofing would have shut down or at least severely interrupted production at the bottling plant. By choosing a urethane restoration coating system in lieu of reroofing, employees were able to continue to work inside the plant throughout the project. Furthermore, the restoration cost approximately one-third as much as a complete roof replacement would have.
The decision to restore or reroof ultimately depends on how much useful life remains in the existing roof materials and how many of the roof’s drainage problems can be corrected by adding drains and diversion crickets. Oftentimes, shortened roof life occurs as a result of thermal failure caused by high roof temperatures. Mitigating those roof temperatures can help prevent the need for reroofing by maximizing the useful life of the materials.
White roof coatings can help protect a roof against excessive temperatures by reflecting visible light and stopping ultraviolet radiation.
Higher Temperatures Shorten Roof Life
According to the Washington, D.C.–based Roof Coating Manufacturers’ Association (RCMA), as roof temperatures increase when exposed to the sun, protective coverings begin to degrade. Rubber, synthetic polymers, and asphalt are susceptible to damage at elevated temperatures.
Roof temperatures can rise above ambient air temperatures by as much as 90 F (50 C). Meanwhile, the rate of degradation for roofing materials (including coverings) begins to accelerate at modestly elevated temperatures—approximately 140 F (60 C). The RCMA estimates that material service life is cut in half for every additional 18 F (10 C) increase in surface temperature.
Although adequate insulation may prevent high roof temperatures from fully penetrating into interior spaces, the heat energy still will be trapped in the roof. Expansion and contraction of roofing materials, especially with metal roofs, can then lead to additional problems and ultimately can result in leaks. Applying a light-colored coating to a low-slope roof can help reflect sunlight and reduce temperatures on the surface of the roof. These lower temperatures should extend roof life, according to the RCMA findings.
Cool Roof Technology
Increasingly known in the industry as cool roofs for their ability to mitigate high temperatures, light- and white-colored roof coatings consist of a polymeric binder blended with pigments and other additives to provide two main benefits: protection of roof membranes for longer roof life cycles and reflectivity of solar radiation for lower air-conditioning costs. Reflecting rather than absorbing solar radiation also helps prevent the heat-island effect, where surface temperatures and overall ambient temperatures rise in the presence of human-made structures. White roof coatings can be applied to a variety of roof substrates or membranes and help protect a roof against excessive temperatures by reflecting visible light and stopping ultraviolet radiation.
According to the RCMA’s Solar Reflective Coatings Council, white roof coatings can provide three key attributes to a building when installed: assistance in shedding water and keeping interiors dry; reduction of cooling costs for buildings with air-conditioning units as well as a reduction of interior temperatures in buildings with no cooling units; and the ability to protect and prolong the roof system’s life cycle by reducing the stress of thermal shock associated with large changes in temperature.
Light- and white-colored roof coatings consist of a polymeric binder blended with pigments and other additives to protect roof membranes for longer roof life cycles and to reflect solar radiation for lower air-conditioning costs.
The Heat is On
Applying a white coating lowered roof temperatures considerably for a roof restoration project for Susquehanna Bancshares, in Lititz, Pa. The regional financial services company occupies a 19th century mill with a roof that had been repaired several times over the course of 24 months. Building owners and roofing contractors opted to install a new white reflective membrane on the 60,000-square-foot (5,575-m2) roof.
On a hot day during the installation, crews took thermal readings using an infrared thermometer. The reading for the white, coated portion of the roof’s surface was 105 F (40.5 C). The black, uncoated portion registered 145 F (63 C)—a difference of 40 F (13 C). The white surface reflected the sunlight back into the atmosphere instead of absorbing the heat into the building where it would increase the load on the air-conditioning systems.
Given the roof’s unique design, with steeply sloped sections that abut vertical window walls, building occupants received an additional, indirect benefit from the white roof coating—increased daylight. With more sunlight reflecting inside, the building’s daylight sensors detected the reflected light and adjusted the interior lighting accordingly, which saved additional energy.
As a result of its roof renovation, the Region Center experienced similar temperature improvements. The white reflective finish coat provided 85 percent reflectivity, which increased energy savings. Tests showed temperatures as high as 169 F (76 C) on the original black roof. The temperature on the new white roof was 97 F (36 C). Because much of the bottling company’s space consists of a non-air-conditioned warehouse, the reflective roof coating reduced heat transfer and created a comfortable environment for workers.
Restoring a roof with a monolithic membrane seal can be a cost-effective alternative to complete tear-off and reroofing, which can generate significant waste that would need to be delivered to a landfill. With manufacturers typically providing warranties of 10 years or longer—and maintenance restricted to simple cleaning and inspections—the addition of membrane seals can help extend the roof’s useful life and minimize the use of raw materials for new products. By choosing a white surface that reflects sunlight back into the atmosphere instead of absorbing the heat into the building, facility managers can limit the energy required for air-conditioning systems. Ultimately, those energy savings will translate into funds that can be allocated to other areas of building operations.
Scott Florida writes about architecture and sustainability from Oakland, Calif.