Time is not always kind to a roofing system. Ultraviolet rays, wind, rain, freeze, thaw; these are all elements that add to the deterioration of a roofing system. It is important that building owners understand the properties and life expectancy of their roofing systems and select strong, long-lasting products.Justice Court Mutual Housing, a cooperative apartment building in Elmhurst, NY, hosted a 13,000-square-foot built-up roof that was in dire need of repair. Though exposed to just over a decade of environmental stress, the building experienced water damage in critical areas, such as in the vertical and horizontal transitions and also in the field of the roof. The existing roof, installed in the early ‘90s, was a torch-down system that had settled and became susceptible to water intrusion. The problem was a flat roof that had no slope and severe ponding.“When there is no slope to the drains, the water has nowhere to go,” said Chris Kelly, principal of CK Engineer PC in Manhattan, NY. “The water stays on the roof and causes major damage.” Water pooled around a concrete block water tower and a 30-foot bulkhead structure that topped the Justice Court Mutual Housing cooperative. The 12-story, art-deco building – constructed in the early 1960s – featured alternating horizontal blocks, which required a roof system specific to meet the needs of the building.The original roof was not properly sloped in relation to the building’s multitude of mechanical units. Only a short 10 years later, the roof deteriorated and began to leak. “Many times with commercial buildings, people focus on the interior of the building – such as the carpet, wallpaper, and interior decorating – when the exterior of the building is the most important,” said Kelly. “The quality of the exterior will affect the whole building.”With the roof as a major component of the renovation, the co-op board and the engineer focused on the long-term needs of the building envelope. In addition to extensive masonry work, the engineer recommended a four-ply, self-adhesive system with tapered insulation that would provide an adequate positive slope for water drainage.Tapered insulation and durable roofing membranes are two essential elements that can prevent a roof from settling while also reducing the threat of ponding. To meet the needs of the Justice Court Housing, Polylass’ Elastoflex SA V and SA P membranes, as well as tapered insulation and crickets, were installed to prevent ponding from occurring once again. “Establishing proper pitch is important,” said Kelly. “All roof components must work together.”The first steps to constructing the self-adhered system involved priming the concrete deck and applying two plies of the Elastoflex SA V base sheet. “We used two plies of Polyglass base sheet as a temporary roof,” said Tony Lado of Bulado General Contractors Corp. in Elmhurst, NY. “The roof was so large that we couldn’t remove the original roof and install the new system all at once. The integrity of the system allowed us to do one section of the roof at a time.”“There’s definitely something to be said about the beefiness of the Polyglass membrane,” said Kelly. “When you compare it to other membranes, it’s substantially thicker.”The thickness of Elastoflex is attributed to its composition of a “true” SBS compound on the top layer and an aggressive self-adhesive compound on the bottom layer. Unlike other SBS membranes, Elastoflex SA V is manufactured using ADESO® technology and is built with a reinforced fiber glass mat to guarantee excellent dimensional stability and provide pliability at low temperature conditions.Following the installation of the two plies of base sheet on the entire roof, tapered insulation and crickets were installed to channel the water toward drains, developing slope. The tapered insulation was laid at 1.5 inches, and even up to 8 inches thick in some areas, to shift water to three drains.“It was a little challenging to install the crickets and insulation behind the water tank and elevator housing,” admitted Lado. “The installation of the base sheet was as simple as laying carpet.”The process was so simple that it only took Bulado’s crew a short 4 weeks to install the entire roof system, with minor weather complications here and there. A quick application of another two plies of the Elastoflex base sheet and the Elastoflex SA P granular cap sheet, as well as repair to the flashings, aluminum panels, and copings, and the roof renovation was complete. “We had twice the production rate using the Polyglass self-adhered membranes,” said Kelly.“The whole process was fast and clean,” stated Bulado. The application method of the self-adhered system involves SEALLAP™ and FASTLAP®, two features that enhance bonding at laps. “There was no waste with the self-adhered system, so it went faster and the roof and surrounding area stayed cleaner.”New York City has outlawed torch-down systems on wood roof decks, and although Justice Court’s roof was concrete, self-adhered is becoming the preferred application method over torch down roofs. “The concern for a safe, flat roof system has already affected wood deck roofs,” said Kelly. “Self-adhesives are important for concrete decks because it avoids hazardous application methods and the roof is expected to last 30 years or more.”Self-adhesive systems that are properly installed with the combination of proper insulation and slope can avoid water damage to the roof. “Good product and good installation are necessary to have a functional roof,” stated Kelly. “The co-op board listened to my recommendations and understood the importance of long-term decisions and proper roof maintenance. Everyone was able to benefit.”
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Courtesy of Chris Cooper
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