Chicago Board of Trade, Chicago

   Not only was its 45-story limestone exterior displaying the dirt and ravages of more than 70 years of Windy City weather; the famed Art Deco interior became a dark and dingy shadow of itself, as renovations removed many of its unique lighting fixtures and some of its rich marble.
   Then, thanks to a combination of circumstances, the building’s owner opted to do a major repair and cleaning of the exterior and a restoration of its interior public spaces – and committed up to $20 million to make sure the job was done right.
   Work began last year – the 75th anniversary of the building’s opening – and renovation of the elevator cars will continue through most of 2007. For much of the stone work, a dedicated and skilled team is wrapping up efforts that most say have been once-in-a-lifetime opportunities to bring the queen of Chicago’s financial district back to her former grandeur.
  
UTILITY AND AESTHETICS
   Kevin Lennon, vice president of real estate operations for the building’s owner, the Chicago Board of Trade, admits that more emphasis had been placed in the past on the building’s usability – such as installing new data lines and other upgrades to its technology infrastructure – than on its aesthetics.
   “Once we completed the internal technology enhancements and we were able to offer our tenants with faster and more-reliable technology, we then turned our attention to the exterior and aesthetic components of the building,” he explains. “We wanted to restore the building to the glorious splendor it had when the building was first erected.
   “Also, a few years ago, the city of Chicago passed a façade ordinance tightening up requirements on maintaining a façade, and there’s a lot of work that needs to be done to keep in compliance with that.”
   William Benesch of Klein and Hoffman Inc., the Chicago-based firm that’s consulted with the building’s owners for more than 15 years on structural issues, says an inspection mandated by the city’s façade ordinance showed significant problems in some areas – although nothing atypical of a limestone building finished in 1930.
   “The stone is held into the backup masonry with steel L-shaped supports, and it’s held laterally with cramps – mild steel that was generally uncoated at the time of construction,” says Benesch. “They rust, and as the rust expands, it pops out pieces of limestone. Once that happens, the rust continues and things continue to deteriorate.”
   Based on the Klein and Hoffman report, and anticipating some tax relief both from the county and the federal government because of the building’s designation as an historic landmark, Lennon says the decision was made to do a full renovation of the façade to minimize future maintenance issues.
   At the same time, C-B-T Corp. committed to repair what Lennon says were some “insensitive” renovations that had been done on the interior in the past, including what he describes as 1970s plastic-laminate elevator cabs.
   “A lot of the damage came in the way of lighting,” he adds. “They had left a lot of the metal and the stone alone, but it needed to be spruced up.”
  
TEAM EFFORT
   Finding companies to handle the project from C-B-T Corp.’s perspective as the developer wasn’t particularly difficult. As with Klein and Hoffman, the company had had previous dealings with two other Chicago-based firms hired for the project: Austin AECOM, the architect of record, and Alps Construction Inc., the construction manager.
   Still, Lennon says the owners went through a rigorous process of evaluating different teams.
   “We did a schematic study of what we were going to do with rough budgets, and then we went and asked a number of people to put together teams of preservation architects, a lighting consultant, an elevator consultant, and a construction manager,” he says. “We interviewed three different teams that could do all that work and we ended up with the team we have.”
   The two companies definitely perform as a team. Austin AECOM’s Chris Conley says his firm serves as the program manager, putting together a team of consultants, including preservation architects Gunny Harboe and Douglas Gilbert, who left Austin AECOM during the project to form Harboe Architects PC.
   From there, Alps Construction had the job of finding people to transform the consultants’ ideas into reality, says that company’s Scott Peterson.
   “We have a pool of subcontractors we do on-going work with, and many of them are qualified for work of this nature,” he says. “We had to search out some specialty subs that could do some of the unique things that happened with this project.”
   Harboe’s Gilbert explains that as preservation architects, that firm has a more-specialized understanding of how to restore historical buildings and materials than architects working on new construction.
   One advantage the project has had is access to many of the records left from when the building was designed by the celebrated Chicago architectural firm of Holabird & Root.
   “We have the original drawings and the drawings that call out the different marble types,” says Gilbert. “We also did some historic research, and there was a magazine called Through the Ages. When the building was completed, they wrote a pretty big spread on it with photos and talked about the marble.”
   He adds that there are at least nine different types of marble in the building, eight of them in the lobby.
   By comparison, the project’s lighting consultant, the Chicago-based Schuler Shook, had to rely extensively on archival photos to replicate the Art Deco light fixtures.
  
PLENTY OF CHALLENGES
   As the preservation architects, the Harboe firm provided management and oversaw aesthetic issues related to the cleaning and color-matching of the façade work. Gilbert calls the work pretty straightforward, despite the mammoth size of the building itself.
   “It was limestone and some terra-cotta restoration,” he says. “They replaced anchors, tuck-pointed, and patched. Plus, they did a cleaning of the building, which had gotten pretty dirty. We were involved in evaluating the different options for cleaning the stone and terra cotta.”
   Morton Grove, Ill.-based Design Installation Systems (DIS) – a company that specializes in exterior high-rise restoration work – won the bid to handle the façade cleaning and repair.
   DIS President Mike Tracy says the engineers determined the scope of the restoration.
   “We’d remove the stone in specific areas that they’d designate,” he says. “We’d inspect the steel that supports the stone, and if it’s corroded, we’d either repair it or replace it. We’d also install flashings. In same cases we’d reuse the stone; in others we’d cut new stone, since we have a fabrication facility within our operation.”
   All the stones that were removed were reinstalled using what he calls, “a little more up-to-date anchoring system” that utilized stainless-steel anchors.
   Many of the stones are 2’ X 3’ and vary in thickness from 4”-12”, depending on location. The most-common thicknesses are 6” and 8”.
   The numerous setbacks on the building – which contribute to its Art Deco appearance – were an area of particular concern. Tracy estimates as much as 70 percent of the parapet areas received attention.
   The parapets and sloped roofs made most of the job difficult to rig; nowhere was that more apparent than with the clock on the building’s north elevation. The carved stones surrounding it weigh as much as four tons – and because the steel supporting them was badly corroded, they had to come off.
   Klein and Hoffman’s Benesch says DIS investigated bringing in a crane to remove the stones one weekend and replace them the following weekend. However, because of the costs involved, the firm took a different approach.
   “They elected to fabricate and construct sort of a sling system – actually a framing system – where they took those stones off and rolled them back,” Benesch explains. “They landed them on beams that were supported on weight-bearing walls so they could take the weight of the stone.”
   In other instances, the company punched through the walls of an old observation deck and used weights and beams.
   Much closer to the ground, DIS also had to replace portions of a carved limestone frieze over the windows of the ground-floor retail level that required bringing in a stone carver.
   “He’s worked with us in the past, and whenever we come into a difficult project he’s willing to help us,” says Tracy. “When it comes to the duplication and matching of detailed pieces, we use him.”
   Harboe’s Gilbert says six pieces of this band were replaced, and the only difference between the originals and the new areas is the crispness of the detail.
   “He did a fantastic job, says Gilbert.
   After testing various cleaning options, the preservation architects and DIS agreed to utilize the soaking method, where the stone is saturated with potable water to the point where deep dirt floats to the surface and then is carefully power-washed away before being reabsorbed.
   Gilbert explains that this was the most-effective and least-damaging to the stone when compared with chemical methods.
   “We installed guttering and all sorts of apparatus on the walls to take care of most of the run-off,” says DIS’s Tracy. “Then, we have crews that monitor the interior of the building to make sure there are no leaks.”
   One unanticipated consequence of the cleaning is that much of the tuck-pointing failed and has been replaced.
  
MATCH MADE IN…
   The restoration and cleaning of the interior stone in the Chicago Board of Trade building presented its own challenges, although Harboe’s Gilbert says that, compared with the façade, the work was pretty straightforward.
   “The stone was pretty much all there,” he says. “The main thing we had to do with the stone was clean and polish it. Most of it probably hadn’t been polished for as long as the building had been there.”
   Where the marble wasn’t intact, Milwaukee Marble and Granite Co. fabricated and installed replacements.
   Thomas Byrnes, head of Milwaukee Marble’s commercial division, says he isn’t aware that the company worked on the building as it was being constructed, but since it dates back to 1894, “We still have a lot of the materials used on older buildings.”
   While the company keeps abreast of what’s being quarried, in this case, none of the stones needed for the job is still being produced. However, Milwaukee Marble also reclaims older stone from buildings being demolished.
   “At the prebid meeting, there were other marble contractors and they just shook their heads,” Byrnes says. “We always try to capture the materials that are being used in renovations and I knew we had the material in stock. That’s why we get a lot of the renovation work we get.”
   That meant being able to supply Carthage marble for flooring around the newsstand and some Aurisina – originally quarried in Trieste, Italy – to clad a replacement wall constructed of drywall a couple decades ago. However, the company was not able to come up with Belgian black marble for some of the trim.
   Dwight Drescher, who managed the project for Milwaukee Marble, says this isn’t the first time the company used an absolute-black granite as a substitute for black marble.
   “We’ve found it’s a better match than using another marble, which traditionally has a vein to it,” he says. “This black marble didn’t, and with the absolute black we were able to achieve a consistent black look.”
   Byrnes says to enhance the match, the company took the finish off the granite, enhanced it and repolished it. Gilbert says a close inspection shows the quartz within the granite, but “It’s a pretty good match colorwise.”
  
CLEANING UP
   The job of cleaning and polishing the interior marble – floors and walls – including the elevator lobbies and a three-story atrium fell to the Chicago branch of Stuart Dean Company Inc.
   Bob Swenie, the general manager, explains that Stuart Dean began by restoring and maintaining the metal in office buildings and expanded to doing other interior surfaces, including stone. He says the company’s contract to clean the metal surfaces in the Chicago Board of Trade building predates his arrival 29 years ago.
   Combining cleaning the stone and the metalwork in the public spaces made a great deal of sense, since they’re closely entwined to create the Art Deco look of the space.
   “The center of the lobby has an atrium that has exposed second and third floors,” Swenie explains. “They have tall scalloped marble wall columns in beige and black colors which have overlaid bronze details. We polished all the surfaces.”
   And, since much of it hadn’t been cleaned since the building went up, both Swenie and Harboe’s Gilbert say the cleaning wasn’t perfect.
   “Especially in the main corridors, near the elevator lobbies, you can see bands where it was very dirty,” says Gilbert. “These are a gray marble, and it was explained that the security guards would stand against the walls with their hands behind them.” 
   “There were some things – some oils – we weren’t able to get out,” acknowledges Swenie. “The marble is 75 years old; it’s a landmark building and we weren’t going to get real aggressive with it.”
   For Swenie, however, the real coup was convincing the building’s owners to abandon their long-time practice of using a topical sealer on the floors and go with a natural polished marble instead.
   “The spec for the floor was just to strip the wax off and hone the floor,” he explains. “Their intention was to put a sealer back on it. I discussed with them the possibility of polishing the floor to a high luster instead. We did a sample for them, they fell in love with it, and now it’s a key part of a beautiful lobby.”
   He adds that plans are to maintain the floors through Chicago’s winter with walk-off mats and aggressive cleaning by the day porters, with his company brought in regularly to repolish the high-traffic areas.
   Alps Construction’s Peterson says for him, the success of the lobby work – and especially the polished floors – has been the high point of the project.
   “It’s amazing; the beauty of the stone is three times what it was after it was polished,” says Peterson. “We had old black-and-white pictures we’d look at, and it’s been interesting to create colored versions of what was there. The clean marble walls, the historic lighting that had to be totally fabricated to match, and the floors have really made those old photos come to life.”
   Austin AECOM’s Conley agrees that it’s been a wonderful restoration.
   “Modern lobbies are more about size and shape and materials,” he observes. “You don’t have the kind of craftsmanship that created the carved and polished stone and the intricate molding and the decorative metal work. What makes it nice is the building is very close to what it was when it was built.”
   Although work on the exterior isn’t expected to be finished until the end of the year and the upgrade of the elevator cars will continue, a few at a time, through next year, C-B-T’s Lennon says he’s confident the project will come in at or under budget, and he’s thrilled with the progress on the project – and the outcome.
   “It’s been a lot of work, especially dealing with the host of obstacles a fully-occupied building presents,” he says. “This really is an historic landmark and an architectural jewel. We pride ourselves on the fact that we’re being good stewards of a great and important building. It’s been an exciting project.”

Client: C-B-T Corp., Chicago
Architect of Record: Austin AECOM, Chicago
Preservation Architect: Harboe Architects PC, Chicago
Construction Manager: Alps Construction Inc., Chicago
Structural Engineer: Klein and Hoffman Inc., Chicago
Façade Contractor: Design Installation Systems, Morton Grove, Ill.
Interior Stone Repair and Replacement: Milwaukee Marble and Granite Co., Milwaukee
Interior Stone Cleaning: Stuart Dean Company Inc., Chicago

This article first appeared in the October 2006 print edition of Stone Business. ©2006 Western Business Media Inc.