The clear choice: Full protection under your solar panel system

By Georgia-Pacific Building Products. 

A project chooses the highest-quality roof cover board before installing a new photovoltaic roofing system. 

When the Maine Mall in South Portland, Maine, needed an upgrade to its aging roof, the owner looked to replace it with a modern photovoltaic (PV) roof system that could provide the building with renewable solar power. The mall is over one million square feet of retail, holding 118 stores – the largest enclosed shopping mall in Northern New England. Not only would this roofing system provide lower energy costs, but federal law allows renewable energy to be deducted from federal taxes as incentive to use solar whenever possible. 

Equipment installation and maintenance can challenge a roof assembly 

While solar roofing systems offer building owners decreased utility bills, they put a significant strain on roof assemblies, primarily from additional foot traffic. Frequent inspections and solar equipment maintenance increases the potential for wear and tear from greater foot traffic or damage from a worker dropping a sharp tool that could puncture the roof. Roofing consultants rank punctures as having the most negative impact on the lifespan of a roofing assembly. 

A high-performance rigid cover board is a must have 

Consequently, most contractors recommend – or even require – the use of a high-performance rigid coverboard when installing a PV system to protect the roof membrane and insulation underneath. With most PV products designed for a service life of 25-30 years, the supporting roof system needs to last at least as long as the solar array itself. 

“Solar roofs cost more than traditional single-ply roofs,” says Michael Gumm, application technologist and business development manager for solar panel manufacturer MiaSolé® and principal of Corporate Roof Consultants. “The additional cost of including a cover board in the project becomes almost inconsequential when designers figure in the life-cycle cost benefits of extending the life of the solar roof system.” With all of this in mind, mall owner and manager Brookfield Properties selected RRK Associates, Ltd., of Gurnee, Illinois, to engineer a Sika Sarnafil 60 mil PVC RhinoBond® induction welded roofing system designed to house a ballasted solar array system covering most of the 167,000 square feet of roof area being replaced. This would provide the owner with a Sika Sarnafil 20-year no-dollar-limit warranty. 

According to Guy Snowden, Jr., principal of RRK Associates, given the scope of the project, the firm knew that a high-performance rigid cover board would be required to support the equipment and withstand foot traffic from routine inspection and maintenance. “Once it was discovered that a solar array system was planned for this location, the use of a rigid and durable cover board was never a second thought,” Snowden explains. “And since this was a recover application and the client had an FM review project scope, an approved cover board was required.” 

DensDeck® Prime Roof Board is the clear choice 

Snowden had worked with a variety of roof boards over the years, but when it came to specifying a product for Maine Mall’s new roof, he felt the choice was simple. 

“Over the years, I have worked with expanded polystyrene, wood fiber, perlite, fiberglass, HD polyisocyanurate and DensDeck Roof Boards. The heavy foot traffic the roof had already experienced combined with the installation of a solar array made DensDeck Prime Roof Board the best choice for long-term performance and durability. Other cover boards would break down or be crushed over a short period of time with the foot and equipment traffic.” 

According to Snowden, DensDeck Prime Roof Board with EONIC™ Technology offers significant advantages over other products. 

“I’ve been in the roof consulting field specifying systems across the nation since 1990, and I feel DensDeck Prime Roof Board provides significant long-term performance, durability and cost savings. Its high compressive strength is extremely beneficial, especially in applications where heavy foot and equipment traffic is expected, as well as roofs in hail zones.” 

Additionally, EONIC™ Technology has doubled DensDeck Prime Roof Board’s resistance to moisture, making it the only roof board to meet the industry’s tough new three-part specification for moisture resistance. This includes five percent total water absorption resistance by weight and one gram surface-water absorption on both sides of the board. 

“I know it has greater moisture resistance than other gypsum products,” says Sarnafil manufacturer’s representative Ned Keating, who, as owner of New England-based Barrier Architectural Reps, helped to choose the materials and assisted on job walks both before and during the project. “We were going over an existing roof that could have had moisture in it. And since the new roof is a RhinoBond® system, moisture could condense under the membrane, sometimes more so than when it’s adhered. This made DensDeck Prime Roof Board’s surface and total water absorption performance extremely valuable.” 

RRK Associates hired Tecta America New England to install the roofing system. One hundred sixty-six thousand square feet of half-inch DensDeck Prime Roof Board was mechanically attached over the existing EPDM roofing system. The white 60 mil Sarnafil PVC roof system was then installed over the top. 

“The existing roof had three to four inches of polyiso insulation on the deck and EPDM membrane on top of it,” explains Mark Drummond, project manager for Tecta America, “The scope of the project required us to slice the existing membrane into 10-foot by 10-foot squares and then install the DensDeck Prime Roof Board over it.” 

According to Drummond, DensDeck Prime Roof Board created an excellent substrate to add protection for the membrane and support solar panels. 

“The product worked really great. Once it was installed, we were left with a nice, firm surface for the roof. Its high compressive strength and moisture resistance made it ideal for this project, especially since it was a re-cover. Most roof board out there are rated around 100 psi, so 900 psi is really impressive. And once the winter snowstorms start coming and snow gets locked in around the shaded sides of the photovoltaic panels, that moisture resistance will really count.” 

Brookfield Properties Retail Group is counting on solar panels to provide many years of reliable, renewable electricity. Thanks to DensDeck Prime Roof Board, they can also count on the roofing assembly to support the equipment, handle the foot traffic and protect the building and its occupants for years to come. 

Original article source: Georgia-Pacific Building Products