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| Perspectives A Quarterly Information Source from Benchmark, Inc. Volume 40 August 2000 |
Client Profile: Starmont Community School Districtby Patrick Marshall The Starmont Community School District, located in northeast Iowa, was looking for a suitable roof system to replace a problematic roof on their high school. Benchmark conducted a roof evaluation of the building, constructed in 1963, and concurred that a roof replacement project was the only long-term watertight solution. The first design consideration to address regarded the existing roof. With two roof systems in place (the original 1963 system, and a recover in 1981), it was necessary to remove the roofs to permit inspection of the steel roof deck, and to remove any wet insulation. The second design consideration was more challenging. The existing roof was level and ponded water in several locations. Drainage of the existing roof was via a series of drains/downspouts, located at several locations along the roof perimeter. These downspouts then drained to an underground tile. Benchmark considered adding roof drains at strategic locations along with tapered insulation to improve drainage. The initial construction estimates for doing so came in at a high per square foot price. A more economical option was to install a tapered insulation system, which would promote drainage to the roof perimeter and add a new continuous perimeter gutter. The gutter could then drain into the existing downspouts/drain tile.The tapered insulation system could be designed one of two ways:
Benchmark eventually eliminated consideration of pouring lightweight insulating concrete because the installation cost was slightly higher, and the "cure" time for pouring lightweight requires a phased construction period. The final specification design was for a mechanically fastened Sarnafil PVC membrane over tapered polyisocyanurate insulation. The final bid package also included a square foot price for removing and replacing the rusted metal deck, painting the rusted steel deck, and adding perimeter gutters. The newly installed perimeter gutters would drain into the existing downspouts, whereas in the original roof, drainage was limited to drains and downspouts only. This 22,500 square foot project began on July 26, 1999, and was substantially complete on August 13, 1999, just prior to the start of the new school year. A final inspection of the new roof system was conducted by Benchmark on September 13, 1999. Now almost one year old, this new roof system continues to drain well and perform leak free. The higher R-value present in the new roof system likely has and will continue to result in lower heating bills. Although Iowa experienced a milder than normal 1999-2000 winter, Starmont's Director of Maintenance, Jim Walker, reported that the boiler used to heat this portion of the school was used far less frequently than past winters. |