One of 2015’s largest roofing projects encompassed a single roof and a quarter of a million pounds of foam.
By Jen KramerOne of the largest spray polyurethane foam (SPF) projects of 2015 was a roofing project that required almost a quarter of a million pounds of foam. Believe it or not, it wasn’t a series of roofs, but rather was one, 220,000 square foot roof on top of Petco’s new San Diego, California facility. Everything about the project was oversized – from the very beginning of the process.
Petco, a national pet retailer, with more than 950 stores, had purchased the enormous warehouse with the intention of converting it into a state-of-the-art, Net-Zero corporate headquarters. But that required a complete renovation.
According to Rodney Peralta, General Manager of Arithane Foam Products, Inc., the SPF contractor that was ultimately awarded the project, the 220,000 square foot roof was comprised of two different substrates: Metal deck with rigid insulation board, along with two Built-Up-Roof (BUR) systems incorporating tar and gravel; the second section of roof encompassed metal decking, as well as strips of aerated concrete with rigid board and a BUR system. Each of the different sections had differing R-values. Additionally, the roof also featured heating and cooling units that were “the size of buses,” thousands of feet of duct work, and 2,800 photovoltaic panels, as well as more than 100 newly specified skylights.
The original specifications called for a single-ply roofing solution, but the specifying architect knew that all of the protrusions and substrates posed a challenge that required a tougher solution. He had worked with SPF, and with Arithane on previous projects, and so Peralta was called in to bid the project. “The GC hadn’t used foam before, but the architect on the project knew that with the challenges being faced, spray foam would be the only solution to the job,” Peralta says.
CONSISTENCY IS KEY (AND SPECIFIED)
Petco wanted an R-value of 25 across the entire roof. None of the four different sections approached that value and traditional roofing options would not attach to the existing roof. Therefore, demolition would be necessary to attach additional board insulation in order to achieve the higher R-value.
But the Arithane crew had another idea in mind. They sent samples of each section of the roof to a lab in order to determine the actual R-value. Then, they determined the exact amount of SPF necessary to bring each section to R-25. In this manner, they not only created a highly customized roof bid, they were able to save Petco the time and expense of demolishing the old roof. “No other bidder bothered to test the roof,” recounts Peralta. “By customizing the roof with SPF, we saved them approximately three months in time and around $750,000 in costs.” Arithane’s creativity and attention to detail paid off. They were awarded the project and SPF – not single ply – was specified for the Net-Zero job.
GO BIG AND GO FOAM
Before any foam could be sprayed, the roof had to be prepped – no small task considering approximately 162,800 square feet of the roof was covered in tar and gravel. This meant that the Arithane crew had to sweep roughly 660,000 pounds of rock into piles and vacuum it off of the roof. In fact, there were so many rocks removed from the roof, that it took 16 dump trucks to haul the loads away. “In an effort to save money and be green, the stones were recycled for use in future construction projects,” Peralta explains.
Then, an intricate staging and scheduling process began.
One of the biggest SPF projects of the year, it was also the biggest project in Arithane’s history. The work scope scheduled roofing for a six month time frame in order to accommodate all of the trades working on the property. But, as Peralta says, “Although it stretched over the course of six months, we ultimately had three solid months of work, because we had to work around other crews.”
Each section of the enormous roof posed a different challenge, but first was the challenge of safely working around so many other trades. “The general contractor was very involved with safety,” Peralta recounts. “Safety measures were extreme on this jobsite.” In addition to safety reports and toolbox talks – daily with their crew and weekly with all the trades on site – new hires had to participate in a safety orientation and sign paperwork confirming the training. “It was vital that we keep others away from the spray site,” says Peralta. So before any spraying occurred, the Arithane crew put up flags around their work area, creating a 50-foot perimeter around the “spray zone.”
Accessing the roof itself came with its own set of logistical and safety concerns. “When we worked in areas surrounded by parapet walls, we didn’t have to worry about falling off the edge of the roof itself,” Peralta explains, “because the walls were 12-feet high and mitigated any fall hazard.” However, while working in those areas, the crew still had to maintain a watchful attitude as there were hundreds of skylights in place during the SPF installation. “The skylights were covered, taped, and masked off, in order to prevent them from being hit with overspray and, more importantly, to prevent anyone from falling through them.” In fact, the Arithane crew completely masked and taped all equipment on the roof – and used a spotter to direct the sprayers away from any dangerous areas, as well as to ensure that all crew members kept a six-foot distance from the edge of the roof while they worked.
In the original design, the building had a second floor, a high-bay mechanical that went through the center of the building. The footprint of this second story was smaller than the first. And by the time the Arithane crew arrived on site, the area had been removed and rebuilt as a metal-decked mezzanine. The mezzanine was encompassed by walls, 12-feet high and 100-feet long on each side. Specifications called for these walls to be covered with stucco. But Peralta and the Arithane crew knew that stucco would be difficult to tie into the original deck and that “the added foam on the two levels of roof, and the counterflashing would be too low to the deck.” So, he came up with a solution that would not only eliminate the need for counterflashing and stucco, but also would save money and make the building more energy-efficient – spray polyurethane foam.
As Peralta describes: “The entire wall was sprayed with one inch of exterior foam that was tied in to both the upper and lower levels. This kept a monolithic seal for waterproofing, and it was more effective than counterflashing and stucco. Further, the walls faced in an East/West direction, so the foam provides extra insulation against the day-long sun exposure.”
When it came time to spray the parapet and mezzanine walls, the crew had to utilize scaffolding to reach the vertical surfaces. When working on the scaffold, the crew wore Guardian six-point fall protection harnesses on top of their Tyvek coveralls, and bright orange safety vests. When spraying, they wore full-face respirators, as well as gloves and steel-toed boots. Non-spraying crew members wore the same personal protective equipment, but used half-mask respirators and goggles, instead of the full-face models worn by their team mates pulling the triggers.
Known for their attention to detail, after all it was their concern with the “individual aspects of the roof” that helped to win them this job, the Arithane crew also goes above and beyond when it comes to containment. Not content to use readily available containment tents, the Arithane crew constructed their own in order to better encapsulate the odd-shaped job site. “We used shade screen material, sewed that together, and covered it with tent canvas,” says Peralta. “The finished tent was large enough for four crews to work inside it easily and comfortably without getting overspray on everything on the outside.”
And how big was the crew? “We started this job with everything we had,” answers Peralta. “Four trucks, each holding two machines and 600 feet of hose (300 feet per machine), eight crew members, eight guns. We attacked it full out for the first month. Then, we slowly started to pare down, until eventually by the end of
the job, we had two guys out there finishing up.”
GOING TO THE DOGS (AND CATS, AND BIRDS, AND HAMSTERS…)
Although the job required a lot of planning and working around other crews, the work itself was relatively straight-forward.
After the rocks had been cleaned off and hauled away, the crew cleaned the specific section of roof that they were to foam. Using power washers, they removed any dust or debris that may have remained on the roof’s surface – whether it was metal
Next, using their airless Graco Bulldog pumps and GX-7 guns, the crew spray-applied SWD Urethane’s Quik-Shield 2000, low-VOC primer at a coverage of a half-gallon per square foot.
Following the primer coat, the crew spray-applied SWD’s Quik-Shield 125 closed-cell, 2.5 density foam onto the roof deck in varying, specifically tailored thicknesses, to achieve the individualized R-values that had been determined through testing. Peralta explains, “In one section, 30,000 square feet received 1.5 inches of foam, in another 84,260 square feet was sprayed with two inches, and 27,200 square feet was sprayed with four inches.”
In addition, the crew also sprayed 8,200 square feet of parapet wall, foaming all the way to the coping cap. Peralta continues, “10,000 square feet of vertical walls between the first and second roof levels were also sprayed with an inch of foam.”
The Arithane crew also addressed the damage caused by the removal of the old mechanical units. “The holes that were left behind were 12-inches deep,” Peralta states. “And there were gaps in between the new mechanical equipment that ranged from five- to 12-inches deep. Also, there was a gap that ran around the 4,000 foot perimeter of the roof. It was 18 inches wide and three- to four-inches deep.” The crew filled the holes with insulation board, spraying Quik-Shield 125 over the top. “This completely sealed the holes and, after, there was no sign of any damage.”
A gray base coat of Quik-Shield 1929 F was spray-applied on top of the Quik-Shield 125 at a thickness of nine mils / gallon. The flame-retardant coating features a high solids, heat-resistant, water-based, elastomeric coating material made from 100 percent acrylic polymers. It is designed to prevent degradation on roofing caused by normal weathering, aging, and ultraviolet exposure. It includes special mildew retardants, and rust inhibitors that help extend the service life of any roofing system.
After the base coat cured, it was quickly followed by the application of a white top coat of Quik-Shield 1929 F, spray-applied at a thickness of two mils / gallon. The coatings were applied in contrasting colors in order to ensure complete coverage. While the top coat was still wet, the crew used a hopper to broadcast #9 limestone granules onto the coating to add durability to the roof’s surface.
Quik-Shield 125 is ranked as a fire-rated assembly by ICC-ES and UL, as well as carrying approvals from California and Miami-Dade. Given that Petco wanted a Net-Zero building, the foam’s LEED (Leadership in Energy and Environmental Design) points were of importance as well. Quik-Shield 125 has a minimum of 9.8 percent total renewable / recycled content. It is 1.8 percent pre-consumer recycled and 4.9 percent post-consumer recycled. It is 3.1 percent rapidly renewable. Further, the time and money saved on the roofing allowed Petco to pursue energy upgrades throughout the entire facility.
“Because we helped them avoid tearing off the entire roof,” Peralta explains, “Petco was able to use the savings to put in additional energy upgrades.” The Arithane bid saved the owners approximately $750,000, which they used to install 2,800, 305-Watt photovoltaic panels on the roof. As Peralta notes, the panels produce 854 kilowatts – enough energy to run 200 average-size homes. “It is as if they have their own power plant up there on their roof. There are so many solar panels up there now, you can hardly see our foam roof.”
He continues, “All of the renovations Petco made to this facility were geared towards energy reduction. Spray foam has not only decreased energy use through insulation value and solar reflectance, but has also been an aid for other energy saving methods. There aren’t many buildings, especially of this size, anywhere in the world, that are near
“The high-end skylights that were installed decrease energy bills by letting natural light in, without adding additional heat. Without spray foam, however, the skylights would cause nothing but problems with air and water leaks, defeating their energy saving purpose,” Peralta says.
“In the 43-year history of this contractor,” Peralta describes Arithane, “this was the largest job we’ve ever completed. The entire job took 150 crew days, spread out over three months. The contractor used 1,100 gallons of low-VOC primer, 240,000 pounds of 2.5 pound foam, 7,200 gallons of coating, and 75,000 pounds of granules. Had single-ply been used instead, the project would have easily been extended by three months.” •
Photos Courtesy of SWD Urethane