Ridgewood Case Study
The rooftop of Ridgewood High School near Chicago is a noisy place. With an extensive re-roofing project underway, two dozen workers scramble about the 120,000 square foot surface – some of them cutting out and removing the decades-old modified bitumen over polyisocyanurate roof, while others install its replacement, a highly specialized roofing system. Soon, the construction noise will end. However, the blasting roar of engines from a steady stream of jets flying in and out of Chicago O’Hare International Airport, only four miles away, will remain. Although Ridgewood High School has served the Chicago suburb of Norridge for over six decades, the airplane noise only became a problem a few years ago when flight patterns in and out of O’Hare changed. Due to glazing that was inadequate to sound isolation requirements, the presence of the original roof assembly and a lack of air conditioning that requires open windows in some classrooms, the exterior envelope of the school was incapable of keeping aircraft noise out of the classrooms.
“The noise can be so bad the teachers sometimes have to stop in mid-sentence,” said Arturo Benitez of DLA Architects, who is overseeing the Ridgewood High School construction project designed to keep noise from making its way into the classrooms serving Ridgewood’s 900 students. Increased flight volumes at airports across the U.S. prompted the federal government to fund a $220 million project dedicated to helping insulate high-impact facilities against sound interference. Case Study Re-roofing of Ridgewood High School Ridgewood qualified because octave band noise testing confirmed that measured noise levels exceeded the 45 dbA maximum acceptable level included in ANSI S 12.60 for schools, LEED® for Schools 2009 and Federal Aviation Administration guidelines for Type 4 buildings (schools). Thus, the school was included in the Chicago Department of Aviation’s School Sound Insulation Program for communities surrounding O’Hare and became eligible for federal sound remediation construction funding to bring decibel levels within FAA guidelines. After considering a variety of options, Benitez and his sound consultant, Laurie Kamper of Threshold Acoustics, determined that a roof assembly that featured alternating layers of Georgia-Pacific Gypsum’s DensDeck® boards and ROCKWOOL TOPROCK® DD Plus stone wool insulation would achieve the desired sound attenuation levels. The new roof assembly is layered as follows (bottom to top):