SPF Roof System Solves Problems for Renovated Office Complex

Historic Pier 70 in San Francisco was a steel mill and a shipyard before it was converted into a modern mixed-use office complex. Central Coating Company applied an SPF roof system from Carlisle Roof Foam and Coatings on 88,000 square feet of the original corrugated metal roof. Photos: Central Coating Company

For more than 100 years, Pier 70 in San Francisco had a storied history, serving as a steel mill and a shipyard that produced destroyers during World War II. The site is a historic landmark, but it sat idle for some two decades before an ambitious restoration project brought it back to life as a mixed-use office complex. The facility now is home to companies including Uber Advanced Technology Group, which set up new offices in 82,000 square feet of the project’s first phase.

When the new tenants found interior temperatures became uncomfortably warm in the summer, Luke Nolan, president of Central Coating Company, was called in to consult on the roof system. With locations in San Jose and Madera, California, Central Coating specializes in spray polyurethane foam (SPF) roofing. The vast majority of its work consists of commercial and industrial re-roofing.

Two inches of SPF added a layer of R-13 continuous insulation, eliminated existing leaks and minimized heat gain from the uninsulated metal roof.

“California’s Title 24 doesn’t apply to historic buildings, so modern energy codes did not apply, and the renovation was completed without thermal insulation,” notes Nolan. “Modern office space was set up in a building where they used to forge steel and used natural ventilation. There was no air conditioning. With the uninsulated roof system, even in moderate San Francisco, radiant heat could cause interior temps to rise to 85 degrees on summer days.”

Nolan used infrared imaging to document the radiant heat entering the building from the roof. Temperatures on the underside of the metal roof topped 135 degrees. He recommended applying an SPF system as the only viable solution to minimize radiant heat, prevent recurring leaks, and preserve the building’s historic status.

Central Coating put together some budgets and commissioned a study by a roofing consultant to quantify the possible reduction in radiant heat. Roger Morrison of Deer Ridge consulting calculated the reduction in radiant heat from various thicknesses of spray foam. The recommendation was for at least 2 inches of SPF, which would add a layer of R-13 continuous insulation.

The next hurdle was making sure the system would meet the standards for the historic building. “The historic architect wanted to make sure that we were able to maintain the look of the corrugated metal on the existing roof,” Nolan says. “That helped us make the decision to go with a 2-inch system instead of going up to 3 inches, because at 3 inches the foam would self-level, and you’d lose the print-through of the corrugations.”

Central Coating was required to do a prototype installation on the building before the project was approved. “We basically did two 200-square-foot areas,” Nolan notes. “Talk about pressure. We knew we had to get it right.’”

After the test areas were finished and approved, the project got the green light.

Completing the Installation

The existing corrugated metal roof was comprised of multiple peaks, many featuring monitors — raised structures that housed rows of clerestory windows for daylighting.

The building was occupied and in use at the time, adding to the complexities of the safety planning. Central Coating had to erect scaffolding and pedestrian canopies to protect passers-by on sidewalks and at building entrances. Safety equipment for Central Coating’s crew members included horizontal lifeline systems on all of the ridges and temporary guardrails along all exposed edges.

The next step was substrate preparation. Crews power-washed the surface, capturing the water, which had to be filtered before it could be returned to the sewer system. The team then installed custom-designed metal flashings at the perimeter and masked the windows before the spraying began.

Working in sections, crews applied a spray foam system manufactured by Carlisle Roof Foam and Coatings. Crews covered approximately 5,000 square feet a day. The total project consisted of more than 88,000 square feet.

Carlisle GP Primer was applied with a sprayer to help increase adhesion of the spray foam. According to Nolan, it dries very quickly, usually within an hour, and the Carlisle PremiSEAL 70 SPF was then sprayed in place.

As part of the goal of maintaining the look of the corrugated metal, the SPF was applied in one application. “You can spray 2 inches in two lifts, but you are more prone to leveling out the surface,” Nolan explains. “We also sprayed the foam a little bit colder than you normally would, which somewhat negatively affected our yield, but we needed to maintain that corrugated look. It’s funny — usually we’re trying to get the foam as flat as possible, but that wasn’t the case here. However, it really worked out well. The sprayers did an excellent job. It was like an art project.”

The Carlisle SeamlessSEAL FR acrylic coating was applied in multiple passes. “The first base coat goes on the same day as the foam is sprayed,” Nolan notes. “Once we covered a certain area, we fell back to apply the mid coat and top coat.”

The top coat was produced in a custom color, Battleship Gray, to match the existing building. Granules were broadcast into the top coat.

Well-Executed Plan

The new SPF system qualified for a 20-year system warranty and achieved its goals, including minimizing heat gain. “The benefit to building comfort was absolutely huge,” Nolan says. “We reduced the temperature of the underside of the metal roof by almost 40 degrees on warm days.”

It was a challenging project, but everything went smoothly, notes Nolan. He credits detailed planning for the project’s success. “This took a tremendous amount of work just to get through the proposal and submittal process — and get the approval of the tenant, the owner, the Port of San Francisco, and the State Historic Preservation Office. And then we just had a really good plan in place for safety and logistics,” he says. “Everyone was very pleased with our process as well as the final result.”

Since the building was occupied, communicating with the tenant was crucial. “There was a lot of coordination with the people working downstairs,” notes Nolan. “The noisier steps, such as installing our metal or installing our safety equipment, we began very early — starting at 5:30 and finishing at 8:30 — so we were not bothering people in the offices during the workday. It’s one of those things that goes to show the importance of having a good plan, communicating that plan, and then executing it.”

The experience stands out for Nolan for many reasons. The project received a 2020 SPFA Annual Excellence Award from the Spray Polyurethane Foam Alliance. The Historic Pier 70 project was named the winner in the in the category of “SPF roof over 40,000 square feet.”

It was also a bit unusual. “For us as a foam roofing contractor, we typically do roofing projects that have the benefit of adding insulation to the building,” Nolan says. “What I mean by that is someone is usually calling us up because their existing roof is at the end of its useful life, and foam will have the added benefits of cutting down their energy bill and making their building more comfortable — but we’re doing it primarily because they need a new roof. This one was different in that we were doing a foam roofing project that was really an insulation job.”

TEAM

Roofing Contractor: Central Coating Company, San Jose and Madera, California, www.centralcoatingcompany.com

MATERIALS

SPF System: PremiSEAL 70, Carlisle Roof Foam and Coatings, www.carlislerfc.com

Acrylic Coating: SeamlessSEAL FR, Carlisle Roof Foam and Coatings