A building’s roof serves as the first line of defense against whatever the skies throw at its inhabitants—wind, rain and blazing sun, even snow and ice in some climates—so it’s crucial for that roof to be sound and well maintained. All it takes is one small crack or hole for the rainwater to get in and, poof! There goes thousands of dollars in repair and potential insurance claims (not to mention the damage it can cause to residents' possessions and property). Knowing how to maintain and repair what's on top of your buildings can ultimately protect its bottom line.
What's Up There?
According to James R. Kirby, AIA, the director of technical services for the national Asphalt Roofing Manufacturers Association (ARMA), the most common types of roofs in dense urban areas are 'low-slope' or flat roofs. “The roof types include asphalt-based roof systems, called built-up and modified bitumen, and single-ply roof systems,” he says.
“The building designer most commonly determines if a rooftop is steep-slope (pitched) or low-slope (flat),” says Kirby. “Most tall buildings have low-slope roofs because the roof is not a visible architectural element. Low-slope roof systems include a roof deck (which in this context is the base layer upon which the other roofing materials sit—not a recreational common area), a vapor barrier if needed, at least two layers of insulation, a cover board, a membrane, and some type of surfacing.”
According to the Chicago Roofing Contractors Association (CRCA) and the Chicagoland Roofing Council, there are several main roofing types in Chicagoland. For flat roof assemblies, these types are common: built up roofing (BUR); modified bitumen; single ply; ethylene propylene diene monomer (EPDM); polyvinyl chloride (PVC) and terpolymer olefins (TPO). Other low slope styles include various types of shingles, including asphalt, wood, slate, gravel and metal.
Since Chicago is such a sustainable city, numerous projects even become energy-efficient when buildings involve the placement of green roofs and reflective roofs as well. According to an analysis conducted by the city several years ago, there are more than 509 vegetated roofs in the city of Chicago accounting for some 5,564,412 square feet of rooftop space, making the Windy City the leader in that category.