Coatings Crew Helps College Greenhouse Grow
By Jen Kramer   

The University of California’s Berkeley campus is known for being on the leading edge of environmental causes. So when the waterproofing system in the concrete pits in their greenhouse nursery began to fail, the school wanted a replacement system that would be both long-lasting and environmentally conscious.

The school needed a specialized coating system and a coatings crew that could handle the unique situation. Although the college would guarantee that no students would be present during the tightly scheduled coatings project, the coatings crew would have to work around the students’ experiments—and would have to become de facto gardeners and movers at times.

“Glass greenhouses contain well over 100 pits, each approximately 12' x 14' square and 3' deep,” explains Steve McCullers, owner and president of Aqua-Proof, Inc., the coatings contracting company ultimately awarded the project. “The tops of the pits are covered with concrete planks. Plants are grown and experiments take place on top of the planks through which water drains into lined pits.” It was that pit lining that had failed and had to be replaced.

But before McCullers and his four man crew could even begin to apply the specified Gaco Western coatings system, the project hit a snag—asbestos was discovered in the old coating.

A Weed In The Garden

“The school called in an abatement company and we left the site,” says McCullers. “The abatement company built tents to contain the area and everything was cordoned off from the students and faculty.”

The asbestos remediation also had an unintended benefit for the Aqua-Proof crew. “Since they removed the old coating and cleaned the concrete, we didn’t have to do major grinding or prepping in the pits,” McCullers states. “It cut down on our prep time.”

The crew’s luck continued as “We were able to salvage all of the old drains,” he says. “And if we had to do any grinding around the drains, we used small 4" grinders and wire wheel grinders.”

 Light repairs came in the form of “some chasing and patching of cracks using hand-held caulking guns and Sikaflex 1A.” Sikaflex 1A is a polyurethane-based, moisture-cured, non-sagging, elastomeric sealant designed for use in concrete waterproofing projects.

 “During prep we also installed stainless screws and new sheet metal baffles at the ends of the pits so that they could run air through them,” says McCullers.

But in addition to moving the occasional plant, the coatings crew also encountered some heavy lifting.

Coaters, Gardeners, Or Movers?

“There were about 15 concrete planks over each pit,” McCullers describes. “Each was 8' long and weighed approximately 80 pounds. These had to be removed and replaced as we worked each pit.”

Fortunately, the planks had holes on the ends, and UC Berkeley provided a special tool that the crew used to move them, “It looked like a pair of ice tongs.” McCullers continues, “Two of our guys would pick up a plank and move it onto a truck. Sometimes the crew from UC Berkeley would help move planks too.”

They would uncover a few pits at a time as the job was bid in three separate contracts. “The project was given to us in sections partly due to UC’s budget concerns and partly because of the plants’ growth and experiment cycles,” he continues. The entire job was specified to run from February through August of 2010. That meant that classes would be in session while coatings work was taking place.

“The school cordoned off the sections in which we were working and we never had to work around the students. It wasn’t an issue.”

Overspray was also not an issue since the specified system would be brush and roller applied.

Green Greenhouse Coatings

Prep in place, it was time for the crew to take to the pit. Suiting up in long sleeved shirts, work boots, gloves, and 3M organic respirators, McCullers and his crew first primed the concrete pit walls and floor with Gaco Western’s GacoFlex E-5320 primer. They used rollers to apply the two-component epoxy at 4 mils WFT.

Next, they used rollers and brushes to install an intermediate coat of GacoFlex UB-64. The two-component polyurethane was applied at a WFT of 25 mils. “We then hand  broadcast sand onto the pit floor,” McCullers explains.

The intermediate coat was followed by a top coat of GacoFlex UA-60, an aliphatic, two-component, fire-retardant, elastomeric, waterproofing, polyurethane coating. The Aqua-Proof crew used rollers and brushes to apply the UA-60 at 15 mils WFT. Important for UC Berkeley, the GacoFlex system—and the UA topcoat in particular—is “environmentally friendly.” According to Gaco’s Website: “Volatile organic compounds are controlled to 330 grams per liter maximum. [UA is] Available in a V.O.C.-compliant suitable for [California’s South Coast Air Quality Management District] SCAQMD.”

After the pits were coated, the crew installed a stainless steel guide rail to protect the coated walls from the concrete planks. “We used SikaFlex 1A to caulk the rail in place,” says McCullers. “Then we put the planks back in their slots over the pits.”   

Methodically working one planter at a time, one section at a time, McCullers and his crew grew the greenhouse coatings project from concrete pits with failed coatings to state-of-the-art, green planters. Is the garden analogy a stretch? Maybe. But maybe not when you consider the patience and care that the crew put into the project. It isn’t a stretch to say that this crew has “green thumbs” when it comes to coatings work.


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