Streets closed by crane activity are a fact of life in crowded, modern-day urban centres. But proponents of one office tower renovation in downtown Montreal are avoiding such a scenario with help from some of the smallest cranes found in construction.

JCB Construction Canada was asked to refurbish the façade of a 28-storey building at 600 Rue De La Gauchetière Ouest. Building owner-developer Kevric Real Estate Corporation wanted to modify and reglaze the curtain wall and build a new main entrance and multi-storey atrium in order to modernize the early 1980s-era structure.

But the project, which began in late 2022, came with constraints: the building is occupied, smack-dab in the heart of the downtown, and directly abutting busy thoroughfares. Kevric wanted to minimize disruption to tenants, keep traffic flowing and reduce risks to vehicles and pedestrians.

After weighing multiple options for staging workers and hoisting materials, the project team settled on a tandem approach, pairing a doughnut-shaped work platform known as Upbrella with two mast climbers to handle equipment and supplies.

But the Upbrella and mast climbers haven’t worked alone. A vital supporting cast of three mini-cranes and other hoisting machines have helped set up and facilitate work. And, when the job winds down, they will help dismantle and close down the project.

New lift on the block

The Upbrella has been akin to a hot-shot Sherlock Holmes, with the mast climbers and a small, purpose-built overhead rooftop crane also proving instrumental in their Watson-like roles.

Produced by Boucherville, Québec-based Upbrella International, the Upbrella is a relative newcomer to high-rise construction, securing interest in a niche where project proponents want to minimize site footprints and impacts imposed by larger cranes.

Just last year, Upbrella saw duty in Nashville with a monorail and trolley guiding it along the circumference of the newly-built roof of the five-storey Jon Bon Jovi’s Live Music Rooftop Bar & Restaurant. The project team wanted to avoid swinging prefabricated exterior panels over next-door neighbours, so they ditched initial plans for a small tower crane.

At 600 Rue De La Gauchetière Ouest in Montreal, the Upbrella fully encircles the 620-foot-perimeter building; anchored to structural weight-bearing steel along the roof periphery and guided by 56 thick, high-tension suspension cables activated by 28 hydraulic cylinders which expand to climb and retract to descend the curtain wall exterior.

Lightweight yet sturdy and nearly fully-wrapped in polycarbonate, the Upbrella is not your grandfather’s work platform. With two decks, one atop the other, crews can attend to two storeys at a time. Workers are enclosed in a space that’s heated and sheltered from wind, rain and snow. Fall risks are minimized significantly, and there’s even a modest toilet with a small holding tank that’s swapped out using the mast climbers.

Success storeys

Setting up proved relatively straight-forward. The first step was to erect the first of the two mast climbers using a boom truck to load its base, with the rest of the mast climber self-erecting. Rated to carry up to 10,000 pounds, that mast climber was more than able to deliver the three 5,000-pound mini-cranes as well as the steel beams and other infrastructure to the roof’s edge.

Crews then used the three cranes —two JMG MC25S carrier cranes and one Maeda MC285 spider crane — to assemble the overhead crane. Designed by Upbrella, this overhead crane was used to transfer the heavy steel from the mast climber to the roof.

Crews then used the three cranes to pick, place and install the Upbrella’s anchoring and guidance system along the perimeter.

Each mini-crane served its purpose. Standing on its outriggers, the spider crane handled materials, while the two mobile carrier cranes carried and placed the beams and other heavy materials.

“The two carrier cranes were doing the back-and-forth with the steel, and the spider crane was more of a stationary crane to assemble,” said JCB project manager David Widmer.

With the mini-cranes running the show up-top, crews attached the cables to the rooftop anchoring and extended them downwards in 13-foot sections matching the height of each of the building’s storeys.

Down below, crews used the boom truck and a 90-ton Link-Belt 8090 rough terrain crane to occupy just a single lane and sidewalk, rather than the entire roadway, as they put the second mast climber in place, assembled the Upbrella, secured it to the cables, and sent it upwards to stage and support workers as they transformed the façade.

The project team considered multiple options before pairing the Upbrella and mast climbers, shared Widmer. Crews could have used a large mobile crane in the 400-tonne range to access the 28-storey rooftop and assemble the supports, but a large machine like that would have only had enough reach to place materials on one side of the building.

“We would have had to switch the crane to a street on the other side to build the other half,” Widmer said. “It would be a nightmare for city circulation.”

Project planners also briefly debated using a helicopter to place the cranes, steel and materials onto the roof. However, while a helicopter could have taken everything to the roof in just a couple trips, the project team decided mast climbers presented the least intrusive and most cost-effective option.

“The helicopter option is really a last resort,” Widmer said. “It’s super expensive, difficult to coordinate, and you’ve got to block off the streets.”

For the façade restoration, the project team considered fully encircling the building with mast climbers and working from those.

This might have been the preferred option a few years ago, before protected platforms such as the Upbrella came on-scene.

However, mast climbers are exposed to the weather, limiting the time work can be done.

“It would have become really hard to coordinate this job at such a fast pace as the Upbrella enabled,” Widmer said, noting that the Upbrella stands to cut the completion time in half, from four to two years.

With the project scheduled to conclude in late spring of this year, Widmer says everything has performed as expected. Each storey has taken roughly three weeks to complete, with crews starting on storeys 17, 16, and 15 as they happened to be empty, then continuing from the uppermost storey and working downwards to ground level.

“They wanted us to start on the empty floors first to get those ready and have a nice showcase floor as soon as possible, but the work could have been done in any order,” Widmer said.

Building occupants were able to carry on with minimal disturbance, though people situated next to the windows did need to vacate their desks for a couple days while work was underway in their immediate vicinity.

Crews working on the Upbrella didn’t need hoisting assistance because the glass panels and other materials they were handling were light enough to be retrieved from the mast climbers and then manoeuvred and installed by hand.

Ultimately, Widmer said the experience reinforces that size and capacity don’t always rule the roost: “Using minimalistic cranes, we managed to do a huge retrofit. It’s very small equipment compared with other construction sites of this value.”

Small cranes, big impact

Grues MFG of Sainte-Julie, Québec, is a Canadian dealer for both JMG and Maeda and supplied the mini-cranes. Sales representative Dany Mireault says small machines are often ideal when a project requires a low footprint, as mechanisms such as turrets allow them to deftly manoeuvre heavy materials in tight or restricted spaces.

Mireault describes the Maeda MC285 as one of the lightest, most compact cranes available. “Smaller spider cranes do exist, but they would be too weak for the job. This was ideal for the weight we had to lift.”

The two carrier cranes, meanwhile, offer a relatively low footprint and were ideal for pick-and-carry duties. “There’s no turret on those,” Mireault adds. “It’s just an up-and-down boom, and a wheel behind that moving left to right like an industrial lift would do.”

MFG has frequently deployed similar mini-cranes for jobs such as erecting hydro power lines and installing balconies and guardrails, where a minimalist approach can help.

“Where there’s no space or bearing capacity from the ground for a regular crane, we can go with these smaller cranes and do the work from inside,” Mireault said. Recalling one job that involved placing materials next to a river, he believes that, “if they had done that with a big crane they would have completely destroyed the site.”

For 600 Rue De La Gauchetière Ouest, proponents opted for the spider crane to be diesel-powered and the carriers to be electric.

There was sufficient space immediately inside the roof area to charge the carriers as needed, whereas the spider’s fixed position made conventional fuel optimal for that machine.

“It was a winter job, and the Maeda MC285 was staying outside, so that was the reason why they took it diesel,” Mireault said. “If it was a summertime job, there would be no reason for diesel; it could have been all batteries.”

Upbrella International president Joey Larouche said the ability of mast climbers and small rooftop cranes to install more than 100 tonnes of temporary steel structure at roof level was inspiring to watch.

“Being able to do that size of project without big tower cranes, with just small installation equipment, was key,” Larouche said.

“There’s a great need for crane equipment that has a small footprint in urban areas that we can install and use on existing roofs. It reduces a lot the inconveniences of closing lanes and streets. It’s a different way of thinking.”