On Saturday, July 15, 2017, a microburst (an intense downdraft of air during a thunderstorm) lifted the EPDM membrane and pavers off the roof of five-story Burton Barr Central Library in Phoenix. Although the building and roof were designed to remain mechanically stable and adapt to structural stress, a sprinkler system on the roof system's metal deck broke, releasing 50 to 60 gallons of water per minute throughout the building.
During an initial evaluation of the building that had been inspired by architect Buckminster Fuller, half the building was estimated to have water damage and more than 6,000 books were destroyed. At one point, there were several inches of standing water on the building's first floor.
The immediate goal for building administrators was to temporarily repair the roof system to protect the building's interior from further rain. That's when the project's general contractor, Rio Rancho, N.M.-based BRYCON Construction Co.'s Arizona Division, contacted Star Roofing Inc., Phoenix, for help.
Throughout the following weekend, Star Roofing workers performed repairs to get the roof "in the dry" to mitigate further interior damage. After repairs, Star Roofing's estimating and operations departments worked with BRYCON Construction and the City of Phoenix to assemble a reroof specification proposal to install a new roof system that subsequently was approved.
In March, Star Roofing's crew began removing the library's existing 43,000-square-foot roof system that consisted of loose-laid EPDM membrane over two layers of 4-inch-thick polyisocyanurate insulation on a steel deck, ballast and 1 1/2-inch-thick interlocking pavers. Twenty-three semi-truckloads of insulation, 6 1/2 tons of rubber and 255 tons of concrete pavers were removed from the library's roof areas.
The roof system's 34,000 pavers weighed 15 pounds each and were placed in small dumpsters, 45 pavers at a time—the crane's maximum allowable weight. The weight on the crane, the angle of the crane to the building and a roof height of 92 feet made the removal process slow and tedious.
All the pavers were recycled at Phoenix-based Cemex USA, where they were ground up and used to make new concrete. The EPDM membrane and polyisocyanurate insulation also were 100 percent recycled through Nationwide Foam Recycling, Framingham, Mass.
Because of possible litigation, the sprinkler system's pipes were marked, disassembled and lowered to the ground and reassembled in the parking lot for inspection by the City of Phoenix and its consultants. Star Roofing workers then installed a support system for the new sprinkler lines on top of the roof deck for the sprinkler contractor to secure the new system.
New roof system
Star Roofing workers then began installing the library's new roof system. Using gray screws to match the metal deck's underside, workers mechanically fastened 5/8-inch-thick DensDeck® Prime cover boards followed by a self-adhering vapor barrier. Next, one layer of 3-inch-thick polyisocyanurate insulation and two layers of 2 1/2-inch-thick polyisocyanurate insulation boards were set in polyurethane foam adhesive. Tapered insulation panels also were used to create additional slope.
To protect the roof areas from future microburst damage, four layers of 5/8-inch-thick DensDeck Prime cover boards and two layers of 2 1/2-inch-thick polyisocyanurate insulation were secured with adhesive 18 feet from the roof's edge, also providing additional roof slope.
Workers then covered all roof areas with 72-mil-thick PVC Sika® Sarnafil® G410 EnergySmart Roof Membrane.
A landmark restored
Three months later, in June, Star Roofing completed its work on Burton Barr Central Library on schedule and in time for the library to successfully reopen to the public Saturday, June 16.
"The collaborative process between BRYCON Construction, the architect and the city was rewarding," says Jeff Klein, vice president of Star Roofing. "But most rewarding was the fact that so much of the roofing materials removed were recycled. We were able to help save thousands of books, and the library reopened to continue being a resource facility for the greater Phoenix community."
Project name: Burton Barr Central Library
Project location: Phoenix
Project duration: March-June 2018
Roof system type: PVC membrane
Roofing contractor: Star Roofing Inc., Phoenix
Roofing manufacturers: Georgia-Pacific Gypsum LLC, Atlanta; Sika® Sarnafil® Inc., Canton, Mass.