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Dangling In The Air, Keeping Buildings Safe: Chicago’s Hands-On High-Elevation Inspectors

A Vertical Access technician performs an up-close investigation.

Mark Danielson has dangled from stone turrets hundreds of feet in the air and watched peregrine falcons dive off the tops of skyscrapers as he stood on a swing stage, secured by ropes and anchors that he installed himself. While these feats might sound thrill-seeking, they’re all in a day’s work for the high-elevation building inspectors and rope access technicians that keep Chicago’s buildings safe.

Nowadays, most yearly inspections take place on the ground outside the building, with teams using high-powered binoculars and drones to search for flaws in a structure’s exterior. But every few years, Chicago buildings are required to undergo hands-on inspections. The structural engineers and inspectors who clamber over the roofs, facades and crenellations of the city’s architectural masterpieces say there’s no better way to gauge a building’s health than to get up close and personal.

“When you see a building from the ground, you’re not getting the whole story,” said Todd Gorrell, principal at Klein & Hoffman, a Chicago structural engineering and architectural firm, where he works alongside Danielson, who serves as the firm’s chief inspector. “Physically being up against these walls and structures, you see things in fine-grained detail that even the best binoculars on the ground can’t replicate.”

Chris Mojica, Klein & Hoffman Inspector III, accesses a rooftop via a swing stage scaffold, hanging from a roof-mounted hydraulic counterweighted apparatus, known as a "house rig."

Up against a building, Klein & Hoffman’s inspectors use far more than their eyes. They touch and press the wall to feel for any movement or weakness and tap masonry to listen for hidden defects. 

“You’re homing in on clues that would alert you to potential problems,” Gorrell said.

Occasionally, inspectors will make small openings in a wall to determine the integrity of the materials behind the external facade and even remove active hazards from a building. 

Gorrell described inspecting an aging stone cornice that projected out from a building high above the sidewalk of Michigan Avenue. A review from the ground had not pointed to any distress, but a light tap with a hammer caused a sizable chunk of the cornice to break off into Gorrell’s hands. 

“We immediately notified the owner of the danger and advised on how to take steps to protect the public,” Gorrell said. “Owners are usually very appreciative of knowing the conditions of their buildings. We’re potentially saving people’s lives and saving owners from serious liability.”

A Vertical Access technician scales a flying buttress along Michigan Avenue, Chicago

Most modern Chicago skyscrapers have wide, flat roofs with metal anchors, which make it straightforward to attach swing stages that give inspectors access to every part of the building’s facade. But on more complex facades and on the city’s many historical structures, inspectors must get creative.

For these jobs, Klein & Hoffman relies on Danielson, its in-house rope access expert, and frequently collaborates with Vertical Access, a national architectural consultancy that specializes in using rope access for investigations in extreme locations.

These inspection jobs often require setting ropes up around structural elements and masonry features like crenellations, turrets and flying buttresses that crown Chicago’s historic skyscrapers. If needed, the Klein & Hoffman and Vertical Access teams can install their own metal anchor points as they go along, trusting their own expertise to know that the anchors will hold.

“We can get to almost anywhere on the outside of a building,” said Evan Kopelson, an architectural conservator and rope access technician at Vertical Access. “The question is, ‘How much effort will it require?’”

A Vertical Access technician performs an investigation from the side of a Michigan Avenue building

Danielson described having to find his way under a 30-foot overhang that projected out from the side of a Chicago building, many stories in the air and too high for a boom lift. His solution was to use a long pole to feed rope through a series of metal rings that spanned the overhang, so that he could inspect the underside of the projection.

Even after a decade of working in rope access, Kopelson still sometimes feels butterflies in his stomach when he realizes he’s hundreds of feet above the ground. In those moments, he reminds himself of his many experiences and thinks back on his training — every member of the Vertical Access team is certified by the Society of Professional Rope Access Technicians. Every project has a SPRAT Level III Supervisor on-site; Level III certification requires hundreds of hours spent on ropes and practice with myriad rescue scenarios.

Klein & Hoffman Chief Inspector Mark Danielson hangs from ropes as he inspects a building.

The Vertical Access team expands Klein & Hoffman’s inspection arsenal, letting it access the hardest-to-reach places around Chicago. Klein & Hoffman’s extensive structural engineering experience and history with Chicago buildings makes the Vertical Access team’s job much simpler, Kopelson said. 

“After the inspection, we’re not often involved with the repairs, but Klein & Hoffman sees these jobs through from start to finish,” Kopelson said. “They know these buildings inside and out and know exactly what structures we can trust and which ones are going to need to be taken apart or repaired. When we’re up on these buildings together, we share a common language.”

Klein & Hoffman Chief Inspector Mark Danielson, Inspector III Alex Perez and a member of Vertical Access conducting inspections via rope access on Michigan Avenue, Chicago

Alexander Perez, who has been an inspector with Klein & Hoffman for 14 years, said he sees himself as a kind of doctor or nurse for Chicago’s buildings, giving building facades physical examinations and working to fix their illnesses. Though he’s climbed through the interior of Grant Park’s Buckingham Fountain and hung from the buttresses of a Michigan Avenue high-rise landmark, Perez said that one of his favorite memories from his work as an inspector was when he was able to pinpoint the source of a water infiltration that had been plaguing the residents of a residential high-rise in Chicago’s Inner Loop.

“We identified the problem and designated the appropriate fix, but the best part was when I showed up the next time at the building,” Perez said. “The doorman greeted me by opening my cab door and embracing me with a hug. The property manager embraced me, too, and told me ‘This is now your home.’ It was one of the best feelings to know they were so happy that I was able to address a problem they had been dealing with for years. I’ll never forget that feeling.”

This article was produced in collaboration between Klein & Hoffman and Studio B. Bisnow news staff was not involved in the production of this content.

Studio B is Bisnow’s in-house content and design studio. To learn more about how Studio B can help your team, reach out to


The Chicago Facade Ordinance requires inspections on exterior walls above 80 feet.