Roof Coatings Articles

It Rains, It Pours: SPF and Polyurea Waterproof Roof

When Tom Leaverton of Pro Set, Inc. was first called out to look at the roof of Grace Plaza, a shopping center in Bridge City, Texas, he figured it would be pretty much the same as any other roof coating project. He was soon to be proven wrong — this was no ordinary roof and it was certainly no ordinary job. Not only was the roof leaking due to inadequate waterproofing, but the existing coating was also causing a major condensation problem inside the building. Add to this the 17 days of consecutive rain while Leaverton and his crew were working on the roof, and this job became quite a challenge. How did the Pro Set, Inc. crew turn the Grace Plaza roof from a case of triple trouble to a watertight success story?

Insulation Innovation


Although Leaverton has worked on much larger projects than the 11,000-square-foot (1,022 m²) Grace Plaza roof, he counts this job as one of his most challenging and unique.  “There were three separate issues going on with this roof, all of which compounded the problem of a roof that wasn’t properly waterproofed in the first place. To start with, the roof wasn’t watertight, so there were leaks whenever it rained. Secondly, there was no insulation installed underneath the roof. This lack of insulation caused condensation to occur inside the building. Because of these issues, we had to come up with a different system than we would normally use,” explained Leaverton.

The four-man Pro Set, Inc. crew had planned on waterproofing the metal roof using a polyurea coating and then installing an American WeatherStar acrylic coating on top of the polyurea. However, the scope of work drastically changed when Leaverton learned of the lack of insulation in the ceiling of Grace Plaza. He knew that if he proceeded with the original plan, the waterproofing solution would only enhance the condensation problem.

It’s Raining, It’s Pouring…Inside the Building

According to Leaverton, the existing acrylic coating was cooling the roof of the structure, which wouldn’t be a problem if the building had insulation. However, without insulation, when temperatures dropped overnight and then warmed up during the day, condensation developed on the ceiling of the building.  In other words, it would “rain” inside the building every day around 10 a.m.

To prevent this from happening, Leaverton proposed to the building owners that American WeatherStar spray polyurethane foam (SPF) be applied to the entire roof prior to laying down the acrylic topcoat. “I wanted to show the owners exactly how the spray foam would insulate the building and eliminate condensation, so I coated one panel of metal substrate with roofing foam and another with acrylic coating. I placed them both on my hot tub cover overnight to simulate heat rising in the building after a cold night. By 10 a.m., water droplets had formed on the acrylic panel and the foam panel was dry,” said Leaverton. He repeated this process several times, always with the same outcome.  When he shared the results of his experiment with the building owners, they were convinced that Leaverton was right. Even though applying SPF would add to the cost of the job, it would be worth every penny.

Closing It Up

During Application

With the new scope of work approved, the crew began surface prep on the roof. They used a Kärcher 5,000 psi (34,474 kPa) pressure washer on the entire roof to remove dirt, debris, and any existing coating that remained on the metal substrate. Then they began the tedious task of fastening 550 roof screws to close all vertical and horizontal laps. “There were many open areas up on the roof where water could leak into the building. Using the roof screws, we were able to manually tighten down and close all these openings prior to the application of the polyurea,” said Leaverton. 

Once all the screws were in place, the crew blocked off the parking lot to avoid overspray issues. According to Leaverton, the crew also erected a tent on the roof of Grace Plaza to further minimize overspray.  The crew then used a Graco 20/35 proportioner to spray 80 mils (2,032 microns) of Poly Pro polyurea — Pro Set, Inc.’s own 100-percent solids polyurea coating — on every vertical and horizontal lap, over each of the 550 roof screws, and around all penetrations.

Leaverton prides himself on this attention to detail, not only when it comes to applying coatings but also in matters of safety. The crew followed standard safety procedures during all stages of the job and wore half-mask respirators, safety glasses, and gloves for all coating and spray foam applications.

AfterLuckily for Leaverton and his crew, the waterproofing stage of the job went without a hitch. “Talk about a test of the polyurea waterproofing,” laughed Leaverton. “We barely finished applying the polyurea when it started to rain.  It kept raining for 17 consecutive days.  This job should have only taken about four days to complete, but because of the rain, it took us 20 days.”  Although the inclement weather was certainly inconvenient, it was not entirely unexpected. As Leaverton points out, January is typically a very rainy month for Bridge City, which is only 10 miles (16 km) from the Louisiana border.

After the sun decided to shine once again, the crew got back to work.  Using the Graco proportioner, they applied one inch (3 cm) of American WeatherStar 2.9 high density, closed-cell SPF to the entire roof. Once the team laid down the SPF, they used a Graco King Air 56:1 spray unit to apply 40 wet mils (1,016 microns) of American WeatherStar Acrylic 211 coating. This acrylic topcoat reduces thermal cycling (expansion and contraction) of roofing substrates, including SPF, and has excellent reflective properties that help reduce energy usage and cooling costs.

Triple Success

Leaverton is proud of the solution that he and his crew presented to the building owner and of how well the polyurea, spray polyurethane foam, and acrylic roofing system is performing on the Grace Plaza building.  According to Leaverton, the roof is leak-free, the building is now properly insulated, and it is no longer “raining” inside Grace Plaza.  And on top of it all, the building owners are conserving energy and saving money.

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