Fluid Applied Roofing System on Scottsdale Performing Arts Center in Arizona
by William A. Kirn, RRC, president, Roof Technology Management, Inc.
From Western Roofing Jan/Feb ’15
Jerry Brown, RRO, principal of Western Roof Evaluation Corporation (WRECORP), Peoria, Arizona, was retained by the Scottsdale Performing Arts Center in Scottsdale, Arizona, to conduct a roof condition survey of their facility. The 56,000 sq.ft. roof was 25 years old, consisting of a lightweight concrete deck covered by a base ply, intermediate ply, and granular surface cap sheet. It was badly wrinkled with numerous splits in the side laps and many small repairs, which had been made over the past several years. The original roof and the spot repairs were in extremely poor condition, specifically along edge details and the field of the roof. Mark Farrell, Progressive Roofing, Phoenix, Arizona, and his team made up of: Jerry Brown; Bill Close, AIA, Architectural Resource Team, and Harry Hummel, KM Coatings Mfg., Inc., also out of Phoenix, installed a roof recover saving the Scottsdale Performing Arts Center tens of thousands of dollars in reroofing costs, and providing a sustainable, long-term performing roof.
Brown conducted a non-destructive capacitance moisture scan of the roof to identify wet areas, mapped the entire roof below the roof surface, and mapped out the roof surface, identifying those areas requiring particular attention. He also took 20+ core samples from the roof to physically confirm the composition of the roof system and lightweight concrete. Based on the field evaluation, Brown recommended a fluid applied roofing system, developed and promoted by KM Coatings as the preferred roof recover option. The facility manager at the Scottsdale Performing Arts Center retained Bill Close to create a CSI formatted specification for the project. Close then collaborated with Brown to create a more detailed specification using the fluid applied roofing system sold by KM Coatings. This KM Shield Coat(TM) fluid applied system had been successfully used for over ten years on numerous projects throughout the southwest U.S. The KM Coatings product provides excellent adhesion, dirt-pickup resistance, and low temperature flexibility. Its long-term performance history has been excellent, especially in areas where intense UV solar radiation typically contributes to premature roof membrane degradation.
Why a Fluid Applied Roof
A lesser known but rapidly emerging roof type is the Fluid Applied Roofing System. The following brief definition describes this system: a single ply roofing system where the coating functions as both adhesive to the substrate and as the waterproofing material. The roof is created in-situ on the existing roof, deck, or insulation, where a reinforcing scrim is typically sandwiched between layers of coating. The system is installed by first cleaning the roof, if needed, then applying the first layer of coating, which acts as a primer and is needed since the cap sheet roof surface will absorb the first coat. A base coat is then applied and, while the coating is still wet, a polyester scrim or mesh is rolled into the wet coating and the scrim is dry-brushed in place. Applying additional coating and scrim layers to create a multi-ply system can follow this, if needed. Base coats are typically dark in color, thus accelerating drying and allowing additional base coats to be installed more quickly.
Fluid applied roofing systems are also unique as they are fully adhered offering dramatically enhanced wind uplift resistance over mechanically fastened and ballasted systems. In fact, all building codes near high wind zone areas have banned ballasted systems. The reason for this is damage caused by recent hurricanes in Houston, Texas and southern Florida and broken windows that were attributed to ballast blown off roofs and breaking windows in high-rise buildings. Moreover, fully adhered systems always have better wind uplift resistance than mechanically fastened systems. This is because of the point load stresses created where the membrane fastener is inserted through the membrane and attached to the deck. These fasteners also act as thermal short circuits because of their conductivity and reduce the theoretical and actual insulative value of the roofing system.
Flashing installation with conventional roofing systems is often complicated as specialty accessory items are required in the form of boots, pitch pockets, flashing grade membranes, counter flashing, etc. Fluid applied roofing system flashing can be easily crafted using only the coating and reinforcing scrim. First, a thick coat of the coating is applied to all surfaces. Then the polyester scrim is cut into the appropriate shape to encase the penetration. This may be in the form of an L-shaped piece, or a cylinder with legs, where the scrim is wrapped around the vertical pipe using coating and the legs, which have been cut into strips, are brushed into the horizontal surface, also using coating. Additional coating is then applied to deliver the required film thickness. Once dry, the flashings and the entire system are again a monolithic, single-ply, fully adhered membrane.
Fluid applied systems are truly sustainable. As the conventional roofing system ages, a second, or recover roof must be installed. A second option would be to apply a maintenance coating. However, this maintenance coating will typically be based on a different chemistry. It will not be the same as the existing membrane, thus creating compatibility problems. With the fluid applied system, as the top surface, or top layer of coating, slowly wears away due to wind particulate scouring, additional coating, the same product that was used to create the membrane, can be spray or roller applied, thus returning the membrane to its original thickness.
Progressive Roofing was contracted by Scottsdale Performing Arts Center to install the KM Shield Coat System, a fluid applied, fully adhered roofing system. Because the Scottsdale Performing Arts Center is both a theatre and museum and the facility cannot be shut down for any reason, it was a key requirement of the project that the installed system be odor-free, and debris and noise be kept to a minimum. The KM Shield Coat System completely met these criteria. The roof measured approximately 56,000 sq.ft. The project was started in December 2011 and completed in April 2012. One-way vents were first installed to completely dry out the roof. A crew of six was all that was required for the project. Brown of WRECORP provided on-site quality assurance.
“Progressive Roofing was proud to be a part of this project. It was a joint effort between the fluid applied roofing system manufacturer, the owner, and our team that made the coating of the Scottsdale Performing Arts Center a success, with the ability to be completed on time, no budget changes required, and to the client’s satisfaction,” said Farrell.
Highlights of this project included: the KM Shield Coat fluid applied roofing system was the best recover option for this project as it eliminated the need for a tear-off; the project did not require shutting down the building HVAC system as all fluid components were basically low or odor-free; the use of one-way vents quickly dried out the roof, and expedited the roof recover process; and the roof was installed quickly, as the roofing mechanics were well-trained in installing the KM Shield Coat System and knowledgeable about fluid applied roofing systems.