A built-up roof comprises multiple piles of felts, fabrics, or mats laminated together with bitumen, asphalt, or—in some states (e.g. Florida)—coal tar pitch. Incorporating alternating layers of piles and bitumen, it is finished with gravel application, mineral cap sheet, or weather-resistant coating. BURs are designed to suit a broad range of waterproofing applications and are highly resistant to punctures and weathering.
However, with two to five plies, labor and materials can be very expensive. As well, the installation of a BUR requires equipment that some roofing contractors may not have. This system also requires a mop-down installation method, which is unsafe to installers.
Metal roofs are systems in which standing seams or corrugated metal panels are mechanically fastened to structure points. Metal roofs provide architects, building designers, and owners with a variety of choices, ranging from the type of metal to dozens of color options. Due to the material’s excellent strength, durability, and fire resistance, these assemblies are often chosen for projects exemplifying the energy-efficient and sustainable building movement. This roof system has a longer lifespan, but can be a costly upfront investment.
Cool and vegetated roofs
Cool roofs use a highly reflective surface to emit the radiant heat back instead of transferring it into the building below. Cool roofs are beneficial to a building and its occupants by reducing energy bills, decreasing air-conditioning needs, and lowering roof temperatures to help extend the assembly’s service life. Further, cool roofs offer benefits beyond the building itself, as they can lower local air temperatures, peak electricity demand, and power plant emissions.
Vegetated roofs contain an abundance of plant life, absorbing rainwater, providing insulation, and helping lower urban air temperatures. These green roofs lower the need for heating and cooling, and can reduce the urban heat island effect. However, this roof type can be more expensive to implement compared to others, and will require continual maintenance.
Coated roof systems can be a cost-effective solution for extending the life of an existing roof system. Coatings provide a highly reflective surface that may lower roof surface temperature, decrease indoor cooling costs, and ultimately reduce overall expenditures. By forming to irregular roof surfaces, coatings close cracks and splits. Once applied, they form a seamless, watertight seal over the entire roof.
A collaborative approach including the architect, specifier, commercial roofing contractor, and building owner to design and install a roofing assembly is essential to prevent critical mistakes. The right system will protect the investment for decades, while the wrong selection could result in costly repairs, damage to the building and its contents, and possibly an early tear-off or reroof. The protection of the investment does not end with the right roofing system, but relies heavily on the roof maintenance program.
Installing a formal, in-house roof maintenance program is the first step in preventative or proactive maintenance, extending the system’s service life. Not all roof maintenance needs to be performed by commercial roofing professionals—some work can be done by the building’s maintenance personnel, who assist with basic items such as keeping the roof free of debris that could block the flow of water to the roof drains and cause ponding. Extreme cases of ponding can cause a roof collapse.
Roof inspections should be performed regularly by trained commercial roofing professionals. Early problem detection makes repairs manageable before they become serious. Inspections and maintenance should also be made after extreme weather events such as tornadoes and hurricanes.
The roof is one of the most important parts of a commercial building. A poorly designed or installed roofing system affects the rest of the structure. Fostering a collaborative working relationship with commercial roofing contractors and designers, with consideration for both parties’ input and expertise, will improve the state of commercial roofing design. An extremely knowledgeable commercial roofing contractor can provide specific roofing systems, allowing the design team to select the proper roof system for the building’s usage and climate.
Mark Gregory, CGC, CCC, is the general manager of RSS Roofing Services & Solutions in Florida. (Headquartered in St. Louis, Missouri, RSS is a subsidiary of MHS Legacy Group, a diversified national holding corporation.) He has more than 25 years of commercial roofing experience and is a Florida certified general contractor and roofing contractor. Gregory is a member of both the National Roofing Contractors Association (NRCA) and the Florida Roofing and Sheet Metal Associations (FRSA). He can be reached at firstname.lastname@example.org.
|After we published this article in the January 2018 issue of The Construction Specifier, a reader had concerns regarding the role of manufacturers. To read the letter and see the author’s response, click here.|