Coating 26 Floors Up And Blowin’ In The Wind

By:Donal Philby
    

Prepping and coating two 26-story towers started one summer and ended the next, with time out to sit by the fire through the cold winter in Salt Lake City. The crew from Bidwell, Inc., finished the project on schedule, but not without a few challenges to overcome, and not without a good bit of swirling wind.

Built 20 years ago, the residential condo buildings were an eyesore, with long dirty streaks staining the coated concrete structures. Air pollutants were to blame, sticking to the rough textured page coat. The owner wanted it restored to the original light tan finish.

Eric Jones is Bidwell’s project manager and son of Bidwell’s owner, Joan Jones. Eric Jones worked from the architect’s report to complete the bid, which included surface cleaning, concrete and parge coat repair, caulking, and a final protective and decorative coating. In addition, any exposed and rusted steel had to be prepared and primed, including the post tension plugs, holes containing the ends of the tensioned wire cables that help support the building and run beneath each floor.



This was the first time Bidwell had taken on a building this tall. Much of their business includes bridge and highway work for the state of Utah, plus parking structures and other buildings.

Bidwell rented four swing stages, 2 feet deep and 40 feet wide, from Safeway Scaffolding in Salt Lake. These were suspended from the 3-foot tall, 2 1/2-foot thick parapet wall. “We used three for the crews and a fourth to leapfrog as we went around the buildings,” said Eric Jones, “working from the roof down.”

The stages were caged off with chicken wire for safety. “The first day a guy dropped a cell phone from the parapet wall and we got to see what it looks like when it drops 260 feet. It just exploded,” said Jones. Everyone on every stage wore a safety harness and was roped to the roof independent of the stages.

The first crew to work a wall power-washed it with a 3500 psi-capable Generac power washer set to 2000 psi to minimize stripping off the parge coat. While the crew could tap into the hot tube water outlets on the roof, the long drop was problematic. The weight of hose and water hanging down stressed the hose until it would break near the top and drop 200+ feet of hose and spraying water down on the workers.


Jones finally contacted EVCO House of Hose in Salt Lake City and ordered high-pressure hydraulic line with garden fixtures attached. This steel braid reinforced hose could support the weight of the drooping hose and also resist kinking at the top of the building.

As the first crew moved to the second swing stage, the next crew began surface repairs to the parge coat and window ledges. The workers used Thoro Patch from local distributor InterMountain Concrete Specialties. The working pot life only stretched to 45 minutes, so often the crew mixed half batches for troweling. To match the parge texture, the crew used 16-grit sand in Thoro Acryl 60 as a slurry and sponge-brushed it on over the hardening patch.

Where cleaning and scraping uncovered bare metal, the crew employed wire wheels on electric grinders to bring them back to “white metal.” The post tension (PT) plug holes proved most annoying, especially with twice as many needing work – as often as 200 per 40-foot wide drop down the face – as estimated.

“If was of these PTs failed, it would release a lot of tension. Dangerous. So we’d chip out the concrete 3 inches deep, then wire wheel buff the steel and coat with primer before patching the holes.”

The chipping process pushed the stage away from the building. On a tip from a local glass company, Jones ordered several suction cups. Stuck to the windows, the suction cups provided anchors for the stages. “The cups were carry-rated at 60-pounds. This was enough to hold the stages steady, but not so strong they would pop the window loose if a stage moved too much.”
And move they did.

“The wind was terrible, some days,” said Jones. “We’d get these vortexes of wind around nearby buildings. Once we had guys on a swing stage and the wind was gusting through there and the stage started swinging sideways so much the guys started screaming. We finally had to pull them in through one of the sliding windows.”

Any cloth or plastic containment acted as a sail and sent the stages swinging. “Seldom did we have a calm day,” said Jones. It certainly affected the coatings process.

Chemrex Thorocoat was selected for the acrylic-based material’s resistance to atmospheric pollutants. They began applying the coating using an airless power roller. But if the wind was up, any runs could be flung 1,000 feet or more. Even the muddy water from a power wash caused $2000 in auto detailing charges.

With containment impractical, they switched to buckets and hand rolling, though the work was tedious and tiring. They masked the windows and applied the coatings as the descended. Then they’d return to the top for a second coat by the end of the day.
The next day the wash crew would strip the masking and caulk the windows with Chemrex Sonolast 150 in 20-ounce sausage tubes using Albion bulk guns.

Despite coming in with the low bid of three, and finding twice the plug work expected, Jones said, “we hit the bid almost exactly as figured.”
 

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