It was a typical roof coating job: The coating system was applied without incident, there was no rain, and there were no challenges or hiccups. According to American Foam Experts’ Project Manager Gus Hunt, the roof housed a number of heating, ventilation, and air conditioning (HVAC) units and there were commercial drains, but “other than that, not that different of a commercial roof.”

But sometimes the fact that a project is straight forward is what makes it unique. And for the client, a real estate developer out of Northern California who wishes to remain unnamed, a straight forward project would probably be music to his ears!

The Truck Stops Here

The project fell into Hunt’s lap when the client reached out to American Foam Experts through the company’s website. “They were having bad leaks in the upper story of their commercial building,” he explained.

The building, which is located in the San Francisco Bay Area, includes offices leased to companies such as Kaiser Permanente. After a pre-inspection, the foam experts determined that the best solution for the leaky cap sheet roof was to apply a coated spray polyurethane foam (SPF) system.

The plan was to prep, prime, foam, and topcoat the roof. But first they’d have to get topside. Although there was access through the building to the roof, the crew generally used a ladder off the back. That’s because American Foam Experts is a “self-contained” company, and the ladder helped them reach the storage containment (aka truck) efficiently.

“We’re fully self-contained — 100 percent,” Hunt explained. “Our machine, our compressor, our hoses, paint pumps, everything is self-contained. It’s a small factory. When we come in, we have everything we need from the foam to the paint. We can do a complete process from our truck.”

For American Foam Systems, that means that they can shrink their operational footprint. “You don’t have to have five different trucks to do three different things,” Hunt continued. On some jobs, he said they’ll need an additional truck to remove gravel, but because that wasn’t needed on this job, they were able to get everything done with just one.

For the customer, being self-contained means that American Foam Systems isn’t “pulling electricity,” as Hunt described it. “We don’t need to plug in. Our air compressors, generators are contained in the truck.” With all systems to, it was time to get moving!

Coats and Colors

Once up top, the five-person crew got to work. The first step: clean the roof.

“We clean the roof; we don’t pressure wash it. If you pressure wash it, depending on the time of year (this was March), it’s not gonna dry,” Hunt explained. According to Supervisor Bobby Stepps, the crew used ECHO blowers with power sweeper on the front. That enabled them to clean “anything where there’s deep areas of dust and debris,” Hunt said.

Because the roof’s perimeter was enclosed by parapet walls, the crew didn’t need to wear any safety gear for heights. They did wear “appropriate PPE [personal protective equipment] for polyurethane foam, proper respirators, and protective clothing with eye protection,” Stepps explained. The main supplier of the safety gear was 3M. 

Using a Graco hydraulic spray pump and roof rig, the crew applied the primer from Accella Polyurethane Systems. The crew spray applied the primer at a rate of ½ gallon per 100 square feet (1.9 L/9.3 m²).

The primer was followed by the SPF. Using 2.8-lb. (1.3 kg) closed-cell roofing SPF, the crew insulated the rooftop. They spray applied the SPF with a Graco H40 using a GX-7 gun, #1 module/#90 PCD (pattern control disk). That was applied at an average of 1 inch (2.5 cm) plus or minus ¼ inch (0.6 cm). 

They also had to take the time to deal with those pesky low areas on the roof. The SPF, also called spray foam, helped with that stage, too. “Of course we spray in the low areas to try to promote drainage as usual,” Hunt said. As Stepps explained,  “We identify the puddles and we string them out, then we pre-spray the low areas to bring them up to grade and apply the foam over the whole roof. And that promotes positive drainage.”

While spray foam can help solve a few problems, it can cause its own, too. “There was a medical facility on the one end so there was a lot of concern for overspray,” Stepps said. “We had to make sure to have wind screens installed when the conditions [rose].”

To finish the system, the crew needed to apply two more layers, and everything on this project was chosen very carefully. To give the client a 20-year warranty, the total system needed to combine to a total 4 gallons per square foot (15.1 L/0.09 m²). But because of the March weather, the crew couldn’t apply any one layer too thickly or there would be a concern that it might not cure. According to Hunt, the magic amount was 1.5 gallons per square foot (5.7 L/0.09 m²) per layer; the crew was not to exceed that. “If you put too much on it’ll just sit there and be thick,” he explained.

To that end, the crew spray applied the basecoat first with Graco silver gun with a 3500 Airless Paint Sprayer. Then, they applied a layer of the topcoat, again at 1.5 gallons per square foot (5.7 L/0.09 m²), followed by a final layer of the topcoat but this time at 1 gallon per square foot (3.8 L/0.09 m²). And the colors of the coatings mattered here too. To start, the basecoat was chosen to be gray. “Because it has a little pigment, the gray is a little bit warmer,” Hunt explained. So the first layer of the topcoat, which was white, could “cure from bottom and top.” Then, the thin top layer was applied, and it was also white.

Results Achieved

In total, the American Foam Experts crew covered the 58,000-square-foot (5,388.4 m²) cap sheet roof with primer, spray foam, basecoat, and two top coats, and they did that all in 10 days.

“Since the roof’s been on it’s been watertight,” Stepps said. According to Hunt, the members of this particular crew have been with American Foam Experts for 15 years, and with the leak-free roof coating system that they left behind, it wouldn’t be a surprise if they continued their success for another 15.