After the four walls of a given structure, the roof is sometimes referred to as the “fifth plane”—and just like the walls that hold it up, the roof is an all-important structure that can make or break a building’s performance. Chicagoland's changeable climate, which as we all know ranges from sweltering hot and humid summer heat to bone-chilling cold in the winter months, often exacerbates trouble spots. If not properly maintained, even a minor roof problem can lead to costly repairs.
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Tyler Amick, director of repair and special services for Sullivan Roofing in Schaumburg says the modified bitumen is the most common type of roof in Chicago. The modified bitumen, he says, comes in a 3-foot wide by 100-foot long roll of roofing material, which makes for a challenging installation.
Reid Robinson, a property preservation consultant with Weathershield, LLC in Oswego agrees with Amick. “Modified bitumen is likely the most common material used for flat roofing applications in Chicago,” says Robinson. “You will see quite a few built up roofs here and there but for your taller buildings, it is a logistical nightmare getting hot tar or a kettle on the roof to do an application. Depending on the contractor, more recent additions to the marketplace are showing up—but these types of roofs are expensive, manufacturer specific and in most cases have a much shorter history to look at in determining the life expectancy of the product.”
According to experts, the modified bitumen is an evolution of asphalt roofing. It’s made from asphalt and a variety of modifiers and solvents. There are several ways of connecting pieces of this material. In a heat application process the seams are heated to melt the asphalt together and create a seal. There is also a cold applied adhesive application process, and some self-adhesive forms of this system. This material is also referred to as APP or SBS.
“In the suburbs of Chicago the most common type of roof on larger square-foot buildings is EPDM [Ethylene Propylene Diene Monomer] because of cost and larger rolls equals faster installation,” says Amick. “However, with the green movement, more people are looking into a white roof. The City of Chicago has a reflective requirement which requires a white membrane or a roof material to be coated to meet the reflectivity requirement. In many of the suburbs it’s the owners’ choice to have a white or black roof; however economics might play more of a role. The bitter taste of poor quality lingers far longer than the initial sweetness of a cheap price.”