When Pratt & Whitney needed a new roof for its 170,000 sq.-ft. aircraft engine-blade manufacturing facility in East Hartford, Conn., company engineers considered three options: single-ply, hot-applied and cold-applied modified bitumen roofing systems. A single-ply system was rejected for durability reasons because the roof required frequent modifications to accommodate ventilation exhausts.
A hot-applied roofing system also was rejected because of odors emitted during installation, says Patrick McCarthy, project engineer, Pratt & Whitney. The plant's 24/7 operations made it impossible to shutdown air intakes to prevent odors from entering the building.
As a result, the company's engineering team of McCarthy, Rajan Anburajan and Bob Vassallo specified a cold-applied, modified bitumen system manufactured by Denver-based John Mansville.
The original roofing system was four-ply cold tar and gravel with cork insulation. After removing the existing roof, installers mechanically fastened 1/2-in. DuraBoard insulation to a 2.5-in. layer of Johns Manville E'NRG'Y2 polyisocyanurate foam insulation. An adhesive heated to 120°F was applied with a spray gun over the insulation. The installers then attached a DynaBase glass reinforced SBS modified bitumen base sheet, followed by a DynaKap modified bitumen cap sheet.