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Waterproof Your Roof

A pharmaceutical company avoids a complete re-roofing project with a spray foam solution

By Jourdan Porter


For those living in California, you are no stranger to the subtropical temperatures that are present in the state all year-round. Air conditioning is the savior for all of the dry, heat-infused summer months and has become a necessity in order to live comfortably. On the other hand, this past winter, the Golden State went through a rain-filled season that called for air tight insulation to stay dry during downpours. Such needs emerged when a pharmaceutical company moved into the commercial building at Nancy Ridge based in San Diego. Knowing the weather patterns that occur, new mechanical equipment and a roof upgrade were going to be needed in the newly inhabited building for optimal insulation in the work place.

Since the two-story building had a metal deck with its original poly-iso board and four-ply roof spanning 23,000 square feet, it was assumed there was going to be damage during the removal and replacement of the mechanical equipment, so the owners wanted to take advantage of the restoration opportunity to upgrade the insulation. The initial re-roofing plan specified to be a single-ply roof with an R-30 value per inch, which would have required the existing roof to be torn off and new insulation boards to be installed. However, once the insulation contractor Arithane was brought in on the job, they knew there was a more efficient way to fix the problem—with spray polyurethane foam (SPF).


Utilizing SPF as the insulation material, meant that an expensive roof tear would not be required. Moreover, the roof could retain its existing insulation boards since SPF would be applied over them (to fasten them to the substrate).

“There are many advantages from using spray foam as the insulation,” says Rodney Peralta of Arithane. “The cost savings, lower carbon footprint, and the value of engineering are all very important factors. Also, spray foam has the highest R-value per inch, so it was the obvious choice on this project due to the fact that the owners wanted the ceiling exposed without visible fasteners. All other roof insulating methods would have required fasteners which would have been visible on the underside of the roof deck.”

Waterproof your roofWith a goal in mind and the optimal material chosen, Arithane got to work. Due to new equipment being installed, the old equipment, curbs, and insulation board stock were removed from the roof. The removal left exposed metal decks that covered about 30 percent of the roof’s deck, and in order to create an even surface, the Arithane crew engineered a solution to fill these penetrations. The team covered the metal areas with poly-iso boards and sprayed foam over them to ensure that the areas were flush with the rest of the roof. By adhering to this method, the SPF was evenly applied to the entirety of the roofing surface, which allowed all areas to match the R-value of the rest of the roof. This action saved the owners time and money.

waterproof your roof

Cementitious coating was used to spray paths from the roof access to the various mechanical units

For the roof system installation, the crew used products made by SWD Urethane. Prior to the SPF install, the Arithane crew powerwashed the entire roof to remove all of the dirt and debris. For the roof system installation, the crew used products made by SWD Urethane. An SWD 2000 primer was applied with a Graco 5:1 transfer pump over the roof deck in order to ensure proper adhesion between the four-ply membrane and the roofing foam. The SWD 2000 is a special, low-VOC product, designed specifically to meet California’s air quality and emission standards. The Arithane team then sprayed over the roof deck 2.5 inches of 2.5 lb. SWD 125 closed-cell foam with a Graco hydraulic pump.

Waterproof your roof

Following the SPF application, crickets were installed as needed to promote proper drainage. To ensure an even surface, the crew members ground down areas that were not leveled. Once the SPF had cured, an SWD 1929F buff acrylic base coat was applied, followed with an SWD 1929F white acrylic top coat. To complete the next step, #9 tenure system white granules were applied to the roofing surface with a Broadcast Coating Tools backpack granulator to increase durability to the roof. To finish off the job, the Arithane team built cement walkways within a four-foot radius surrounding each of the newly implemented mechanical areas (i.e. air conditioning units) that led from the various units to the roof access.        

Due to the low parapet walls, the edges of the roof were flagged for safety and the Arithane crew was tied off when working within six feet of the edge, along with spotters to help eliminate fall risk. Additionally, the crew members wore PPE including goggles, gloves, respirators, and Tyvek suits for the entirety of the job. In order to mitigate overspray damage, the crew came across a bit of a challenge­—the spray tents they owned were too small to cover the large surface space, so the members utilized their ingenuity and sewed all of the spray tents together. To comply with safety and quality standards at the job site, the Arithane crew were assigned to fill out daily activity reports. “We had to build a daily to report on the humidity, the dew point, times in which they sprayed, how much foam they sprayed every day, and more,” explains Peralta.

Waterproof your roof

LEFT: The exposed metal decks were covered with poly-iso boards and spray foam; ABOVE: The completed roofing system has a 10-year warranty guarantee

After 21 days of labor, the Arithane crew developed a roofing system that will lower the energy costs that the owners will accrue in the future. With a 10-year leak-free warranty, the pharmaceutical company will no longer have to worry about water penetration that could cause damage to their labs and will now allow the facility to safely service pharmaceutical needs. Peralta confirms, “Our warranty is very important to our customers since water leakage is a common problem in roofing. With wet winters in our area, it is key to keep customers safe.”•

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