Tall Orders: Restorations and new-build projects drive crews higher
Assessing needed repairs on high-rise buildings often requires Structural staff to repel down the exterior. Photo courtesy of Structural.
From repairing cladding that fell from a 20-story office building to erecting a high-rise residence on a tight urban site to restoring a towering, historic dome, construction professionals are increasingly being called upon to conduct their work at lofty elevations.
Successfully completing those projects requires robust and creative designs for scaffolding, hoists and other access equipment; heightened efficiency in moving workers and materials through vertical sites; unwavering attention to safety; and a select breed of courageous construction professionals.
Aging Buildings
On Baltimore’s North Charles Street and Center Plaza, office building owners suddenly needed critical and exceedingly difficult repairs. On North Charles, a section of façade on a 20-story building had come loose and crashed to the sidewalk below. At Center Plaza, an explosion inside the top floor of a 12-story building had pushed exterior, precast panels out of place by as much as two inches
Crews from Structural were called in to provide access to the building exteriors, assess the damage and complete repairs. The first step was to provide “rope access.”
“We drop a rope and the person doing the investigation would repel down the building and look at the conditions,” said Melvin VanSkiver, Safety Coordinator/Trainer.
“They’re not doing a lot of physical work as much as they are looking, taking pictures and maybe removing some sealant.”
To complete the repairs, crews would need broader access, ideally by hanging a swing stage from the roof. However, providing that access on the two downtown office buildings and other repair jobs often isn’t easy. Some buildings can’t support the load of a swing stage and the shape of buildings can prevent crews from accessing damaged areas from a swing stage.
To match construction schedules and the complex architecture of Baltimore City Hall, ECRS opted to use system scaffolding and erect the scaffold in eight phases. Photo courtesy of ECRS.
“We have done some work for Johns Hopkins and the University of Maryland where the structures were built in the 1800s and the wood structure on the roof wasn’t conducive to us putting a lot of weight on it,” VanSkiver said. On other buildings, “you have to work past balconies or the building is larger on top, so the swing stage will put you right up against the building for the first few floors, but below that you’re kind of floating in the middle of space.”
For the Center Plaza repair, Structural had to coordinate work between an interior crew and a worker who descended the exterior in a bosun’s chair.
Meanwhile, calls for building repairs and remediation are increasing.
“There is a big initiative in major U.S. cities to look at old buildings and address life safety issues with those buildings,” said John Lunn, Construction Manager.
Last year, Structural completed extensive remediation of century-old terra cotta on 7 E Redwood Street and expects to conduct similar work on other nearby buildings.
“Some of our bread-and-butter work is on buildings experiencing water infiltration,” said Vince Armeni, Senior Superintendent. “We will remove three to four courses of brick, treat the steel or replace it, and install a flashing system that allows any water that gets behind the wall to be wicked away.”
But increasingly, the company is also repairing structural problems in old buildings because “for some reason, people don’t equate the word maintenance with masonry or concrete,” Armeni said.
Historic Renovations
To facilitate restoration work at the Maryland State House, Scaffold Resource erected a massive, compression ring scaffold around the historic dome. Photo courtesy of Scaffold Resource.
Completing larger renovations on historic buildings presents another level of challenge. Scaffolding and hoists cannot make significant penetrations into exterior marble or other historic façades, so contractors have to devise other ways to anchor that equipment.
For the exterior renovation of Penn Station, Scaffold Resource completely wrapped the building in scaffolding secured through a compression system.
“We were fortunate that they were going to take the windows out of the building,” said Mark Tsirigos, Vice President of Business Development at Scaffold Resource. “We sandwiched the walls at the window openings with a beam on the inside and a beam on the outside. We bolted through those, drew it up tight almost like a clamp and tied the scaffolding onto that.”
For the restoration of the Maryland State House dome, Scaffold Resource encircled the structure with scaffolding anchored with a “compression ring” that pressed against the sides of the dome but didn’t penetrate them.
For the current restoration of the rest of the State House, East Coast Rigging and Scaffolding (ECRS) has surrounded the building with a free-standing scaffold “covered in scrim debris netting that has an image of the state capital printing on it,” said Joel Ross, Director of Sales and Business Development. “From a distance, you might think you’re looking at the actual building, not the scaffolding.”
Designing scaffolds, however, involves more than avoiding damage to façades and meeting the load tolerances of existing structures. Scaffolds must provide all trades with access to the areas they will work on, and match the number and schedule of workers onsite, Ross said.
At Baltimore City Hall, ECRS divided its scaffold plan into eight phases to match the renovation schedule and utilized system scaffolding to provide full access around City Hall’s complex architecture.
“System scaffolding is like a Lego system,” Ross said. “You can put different pieces together and they give you all the access you want.”
Yet planning access for renovation projects is typically a compressed process.
“Everybody seems to forget about the scaffold guy,” said Steve Querna, Vice President of Sales at Scaffold Resource. “When you get a set of drawings, they don’t ever show the scaffolding or hoisting that we have to build,” Tsirgos said. “We become a turnkey design-build contractor for that.”
Since scaffolding/hoist plans are often drafted within weeks, the success of a plan is greatly influenced by the ability of other subcontractors to weigh in quickly and specify their access needs.
Building Taller
New construction presents a different mix of challenges and solutions for high-elevation projects.
On the campus of Morgan State University, Gilbane Building Company has employed several key processes to facilitate efficient construction of two student residence towers on a tight site.
High-rise construction, such as the new residence towers at Morgan State University, require extraordinary access planning for tight, vertical sites. Photo courtesy of Gilbane.
Early planning on how to use scaffolding, hoists, mast climbers and swing stages in the project ensured that imbeds to anchor that equipment were included in the design for the towers’ post-tension concrete structure, said Jonathan Dickinson, Senior Project Executive at Gilbane.
In addition, Gilbane arranged for its concrete subcontractor to precast concrete stairs offsite. Then as each deck was installed, “they would make modifications in the stair towers with imbeds so they could easily set these stairs in place. So, as we built up, we brought the stairway with us,” said Project Manager Darren Murphy.
“This is the first time I have ever done that, but it is so practical that I can’t see why people wouldn’t do it all the time,” Murphy said. “It took a lot of strain off of our material hoists and our man hoists because people could go up and down the stairs.”
Carefully planned “crew flow” and scheduling of each subcontractor’s work on each floor of the building has been essential to project efficiency on the congested, vertical site.
“As we move up in the building and bring on more subs, we are putting more demands on our access points,” Murphy said. Currently, about 180 workers from 20 subcontractors are working on the second residence tower daily. “A lot of things can go wrong working at heights because you are very limited with your access points.”
The project, he added, also made extensive use of prefabrication to streamline onsite work.
Safe Operations
One universal aspect for any high-elevation construction project is an intense focus on safety
“Falls are the leading cause of injury and death on construction sites,” said Jay Stephan, Field Operations Manager at Diversified Safety Services. “Guard rails are the number one way that you can engineer that hazard out.”
There is also “continuous R&D in the fall-protection industry,” Stephan said. “There are constantly new products coming out – new anchorage systems, new harnesses and body wear. There are new systems for rescue and self-rescue.”
For construction workers involved in repelling down buildings, “there are new devices that if you push too far or try to go too fast, the device will lock itself,” VanSkiver said.
“It is our job at the beginning of the project to remove safety concerns,” Dickinson said.
In addition to implementing rigorous safety protocols and installing guardrails and other protective measures, safety on a congested, vertical construction site, he said, requires constant coordination with subcontractors to ensure everyone is aware of changing site conditions, safe access points and hazards.