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.”
How long a roof lasts will depend on what it’s made of and how it’s maintained. “Shingles will typically last 30 years, while an average flat system lasts 15 years,” says Chuck Goss, president and founder of Cooper Roofing, based in Trenton, New Jersey. “Different manufacturers offer different premium material with higher warranties at very high premium prices.”
No matter how durable the materials or how well they were installed, at some point a roof will begin to deteriorate under stress from the elements. Sections can begin to break down, allowing moisture to seep in and cause damage. The most vulnerable parts of a roof are at the perimeters and at penetration points, such as vents, skylights, and water tank footings.