The Mason County Career Magnet School, part of the Mason County School System in Maysville, Ky., brings together students from four area high schools for the opportunity to learn skills in nursing, welding, automotive repair, electrical maintenance, and more. Many students who participate in the programs earn college credit and continue their education at the postsecondary level. Others gain successful employment upon graduation from high school, and still others pursue advanced technical training.
This particular career technical school was set for a complete renovation in early 2020, including the roof. Through a bidding process with a general contractor (GC), Purefoam Roofing & Insulation won the project and came onto the scene in April. With a total of 20 employees headquartered in Shelbyville, Ky., the team at Purefoam brought four employees to the jobsite along with three spray polyurethane foam (SPF) rigs. Specifications called for a coated SPF system on top of the original steel roof deck.
Starting Off in Good Shape
The first step taken by Purefoam was to put safety precautions in place. Warning lines, cones, and flags were placed around the perimeter of the roof to indicate a 6-foot (1.8 m) working distance from the edge. The crew also donned Tyvek spray suits, spray socks, MSA Safety’s Advantage 200 LS half-face respirators, and gloves for the SPF application.
With safety taken care of, the crew was ready to get to work. Fortunately, no repairs were needed to the metal. So the Purefoam crew began by power washing the entire 35,000-square-foot (3,251.6 m2) roof to remove dirt and debris. Three 3,500-psi (24.1 MPa) power washers from Citation were used for this process, which took two full workdays. “We had three of those going with, of course, three guys washing, three guys pulling hose, and one guy on the ground keeping them in gas,” said Manuel Adler, owner of Purefoam. As a plus, there was no concern about the spent water running off the 3:12 pitch roof; it was allowed to run into the gutters because “it wasn’t that dirty,” he said.
“We power washed everything, and then they put the penetrations through the next day,” said Adler, speaking about the work done by the GC. “There were some new penetrations that came through because of the inside work. But, of course, those got sprayed around. And an elevator shaft that came through the roof. But as far as the metal itself, it was all in good shape.”
Once the penetrations were in place and sealed, the Purefoam crew also didn’t have to worry about being in the way of other trades or the GC. “The GC was framing up inside and doing drywall and painting, electrical, and plumbing inside. But we didn’t really affect them,” Adler said.
In final preparations before the SPF application, Adler’s crew checked the roof fasteners. “We always go through and make sure they’re tight,” he commented. “There wasn’t any rust, either. If there would have been any rust, we would have put some rust inhibitor primer on it. But there wasn’t. Therefore, it wasn’t needed.” The crew also put plastic over the gutters to keep any overspray out of them.
One Stage at a Time
Moving on to the application of the foam, Purefoam installed approximately 1.5 inches (3.8 cm) of 3-pound (1.4 kg) BASF SKYTITE SPF, also called spray foam, directly on the existing metal roof. This was followed by two coats of BASF Elastocoat S-5000 silicone with 3M granules broadcast into the wet topcoat for a 20-year manufacturer’s warranty.
Adler described the equipment used on this job: “We have a fully enclosed, 24-foot [7.3 m] trailer that has a 40-kW [53.6 hp] generator. We use Graco H-40 proportioners, 400 feet [121.9 m] of heated hose, and a Graco Fusion AP gun.”
While spraying the SPF, the Purefoam crew utilized a homemade windscreen. “We just make them out of PVC [polyvinyl chloride] pipe and landscaping netting or mesh,” said Adler. “We make them 5 feet by 6 feet [1.5 x 1.8 m]. Basically, a guy just stands behind them and keeps the wind off the sprayer.”
The roof had to be done in stages. A four-person crew “took six days to do the foam,” Adler recalled as he described the process. “Whatever we sprayed in a day, we put basecoat on as well, so it wouldn’t burn. We were doing approximately 5,000 square feet [464.4 m2] per day, foam and basecoat.”
The “burn” he spoke of is actually a deterioration from ultraviolet (UV) rays that happens to uncoated spray foam within 72 hours. “You have to do it in stages or it will burn real bad,” Adler explained. “The manufacturer likes you to coat whatever you foam in the same day.”
In this case, the Elastocoat silicone served the protective purpose. It was applied at ~15 mils (381.0 microns) wet film thickness (WFT). “The basecoat is a dark gray,” stated Adler. “That is put on with a Graco 833 pump. We finished all of the foam and basecoat first. Then we went back and power washed, if needed, again. Then we sprayed the S-5000 light-gray silicone [topcoat] on the entire roof and broadcast 3M granules on it as we were going. That also got 15 mils.” All SPF and silicone materials were spray applied, and all drums and materials stayed on the ground.
The 3M granules, made from ceramic, were put down as another layer of UV protection for the SPF. A Roofmaster granule trailer, which also stayed put on the ground below, broadcast granules into the wet coating at a rate of 2 pounds per 100 square feet (0.9 kg/9.3 m2).
A Straightforward Job
Fortunately for the crew, the weather in the north-central Kentucky town of Maysville held up rather well, and there was only one rain day. Therefore, the crew was able to complete the coated SPF application on the roof over the course of nine days. “There was a rain day,” recalled Adler. “It stopped us a little early and kind of sprinkled throughout the day — just enough to keep us down.”
Two adjacent buildings also had to be protected during spraying, but this, too, did not present a problem. Adler said, “Every day we got pretty lucky, and the wind was blowing to the back where there was nothing.”
Were there any other unique challenges on the job? Not this time. “It was pretty straightforward,” per Adler. “I know the articles like the challenging things. But it was pretty laid back. The application is a good application.”
And with a 20-year warranty, that good application is even better!