By John Plescia – CEO of Star Roofing Inc.
At 6:00 pm, Saturday, July 15, 2017, a microburst* over the roof of Burton Barr Library* in Phoenix, Arizona, lifted the roof structure (which it was designed to do) and was strong enough to lift the membrane and the pavers that were meant to protect the structure during such extreme weather conditions. The structure (including the roof) was designed to remain mechanically stable and adapt as the stress on the structure increased.
The stress to the roof ultimately led to a broken sprinkler system in the high roof. The sprinkler system was under the roof system on the top side of the metal deck. Water rained down from a raised fifth floor which allowed the water to spread further through the building. Upon initial evaluation it was believed that 50% of the building had water damage. At one point there was several inches of standing water on the first floor. The immediate goal was to temporarily protect the roof from any further rain, since the weatherproof membrane had been disturbed but not the roof structure and to dry out the moisture in the building.
Star Roofing Emergency Services was called by BRYCON Construction Company and a crew of Star roofers spent the weekend preforming roof repairs to get the roof in the dry to mitigate further interior damage. Star Roofing's estimating and operations departments worked with BRYCON Construction and the City of Phoenix to put together reroof specification and budget pricing to install a completely new roof.
The existing roof system consisted of loose laid EPDM over 2 layers of 4" ISO insulation on a steel deck. Ballast consisted of 1 ½" thick interlocking pavers with a complete removal of the existing system required. In all, 23 semi-truck loads of insulation, 61/2 tons of rubber and 255 tons of concrete pavers were removed. Star Roofing recycled 100% of the pavers at Cemex USA in Phoenix, where they grind the concrete pavers and use the material in making new concrete. The EPDM and the roof insulation were also recycled thru Nationwide Foam Recycling.
Access and a roof height of 92 feet provided challenges, especially in the roof removal process. 34,000 pavers each weighing 15 pounds, were placed in small trash bins, 45 at a time, as this was the maximum weight per bin that Star's crane could handle with the JIB extended and due to the angle of the building.
Another untypical situation was work required due to the replacement of the damaged sprinkler system. The sprinkler was above the roof deck, buried under the roofing system. Because of possible litigation, the sprinkler system piping was marked, disassembled and lowered to the ground. The system was then reassembled in the parking lot for inspection by the City of Phoenix and their consultants.
The new roof system is 5/8" gypsum board mechanically fastened with gray colored screws (which had to be kept in a straight line) to match the underside of the exposed metal deck. A self-adhered vapor barrier was installed over the gypsum board. Next, one layer of 3" ISO and 2 layers of 2.5" ISO insulation, all set in adhesive, were installed. Additional taper was also installed to provide slope.
A special installation was required at the perimeter to protect against another wind occurrence. Four layers of 5/8" gypsum board and two layers of 2.5" ISO insulation, all secured with adhesive were installed 18 feet in from of the roof edge. Which provided additional roof slope. The entire area then received a Sarnafil 72 mil. FleeceBACK PVC membrane that was fully adhered and carries a 25-year warranty.
All in all, the project progressed smoothly and was completed on schedule and our environment got a little help from the recycling.
For more information on this project please visit www.starroofingaz.com
*Microburst is an intense small-scale downdraft produced by a thunderstorm or rain shower. They are comparable to a tornado, and in some cases cause worse damage. Wind speeds as high as 150 mph are possible in extreme microburst cases.
*Burton Barr Library is a five-story building opened in May 1995 and is 28,000 square feet. The building incorporates a roof structure inspired by Buckminster Fuller's tensegrity structures and currently houses 1,000,000 volumes.
Project Name: Burton Barr Public Library, 43,000 Sf. Owner: City of Phoenix
General Contractor: BRYCON Construction
Roofing: Star Roofing Inc.