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Scottsdale Performing Arts Center Reroofing Project

William A. Kirn, RRC, President, Roof Technology Management, Inc.  wkirn356@verizon.net

“This roof will require a tear-off”, said one contractor.  Another wouldn’t even consider the project, as being too difficult.  However, Mark Farrell and his team at Progressive Roofing, Mr. Jerry Brown, RRO, WRECORP, Mr. Bill Close, AIA, Architectural Resource Team and Harry Hummel, KM Coatings Mfg., Inc., viewed the project very differently!  Together they enabled the Scottsdale Performing Arts Center to save tens of thousands of dollars in reroofing costs, and still provided a sustainable, long term performing roof.

The Roof Evaluation Survey

This story begins with Mr. Jerry Brown, RRO, principal of Western Roof Evaluation Corporation, (WRECORP) who was retained by the Scottsdale Performing Arts Center to conduct a roof condition survey of their facility.  The roof was a 25 year old roof consisting of lightweight concrete deck covered by a base ply, intermediate ply and granule surface cap sheet.  The roof was badly wrinkled with numerous splits in the side laps and many small repairs had been made over the past several years.  The photos below document the extremely poor condition of the original roof.  Note carefully the poor condition of the spot repairs, specifically along edge details and on the field of the roof.

Mr. 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.

See photo below.

The Specification

Based on the field evaluation, Mr. 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 Mr. Bill Close of Architectural Resource Team to create a CSI formatted specification for the project.  Mr. Close then collaborated with Jerry Brown of WRECORP to create a more detailed specification using the fluid applied roofing system sold by KM Coatings.  This KM Shield Coat fluid applied system had been successfully used for over 10 years on numerous projects throughout the southwest US.   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.  

Most roofing professionals are familiar with conventional roofing systems.  These include asphalt, modified bitumen, thermoplastic single ply membranes including PVC, TPO and CPE and thermoset membranes, such as EPDM, sprayed-in-place polyurethane foam and metal.  

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 as 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 (mesh) is rolled into the wet coating and the scrim is dry-brushed in place.  This can be followed by applying additional coating and scrim layers to create a “multi-ply system”, 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 area 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 (read: prone to hurricanes) have banned ballasted systems.  The reason:  damage caused by recent hurricanes in Houston and southern Florida and broken windows 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 (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.

However, with the fluid applied system, as the top surface (top layer of coating) slowly wears away due to wind particulate scouring, additional coating (same product that was used to create the membrane) can be spray or roller applied, thus returning the membrane to its original thickness.

The Project

Progressive Roofing was contracted by Scottsdale Performing Arts Center to install the KM “Shield Coat System”, a fluid applied, fully-adhered roofing system.  A key requirement of this project was that the Scottsdale Performing Arts Center is both a theatre and museum and the facility cannot be shut down for any reason.  Thus, the installed system must be odor-free.  Also, debris and noise must be kept to a minimum.  The KM Shield Coat System completely met these criteria.  The roof measured approximately 56,000 square feet. The project was started in December 2011 and completed in April 2012.  A crew of 6 was all that was required for the project.  Mr. Jerry Brown of WRECORP provided on-site quality assurance.  

One -way vents were first installed to completely dry out the roof.  Photos below document the installation. 

Field Installation in Progress

Internal Drain Sump Flashing Detail (Sump has been fully fabric reinforced before collar is installed)

Field Installation in Progress

Field Installation Completed (Note one-way vents installed)

“Progressive Roofing is proud to be a part of this project. It was a joint effort between the fluid applied roofing system manufacturer, owner and our team that made the coating of the Scottsdale Performing Arts a success, with the ability to be completed on time, with no budget changes required and to the client’s satisfaction”, Mark Farrell, President, Progressive Roofing.

Aerial View of Completed Project 

Conclusions:

  1. 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.
  2. The project did not require shutting down the building HVAC system as all fluid components were basically low or odor free.
  3. The use of one-way vents quickly dried out the roof, and expedited the roof recover process.
  4. 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.