Monadnock Building Words: Cass SternPhotos: ilbusca, stevegeer, Conchi Martínez, Rawf8Chicago’s Monadnock Building doesn’t dominate the skyline the way it once did. Surrounded by steel-and-glass towers, the dark brick structure can seem almost understated. But for anyone in the masonry industry, it remains one of the most important buildings ever constructed.When work on the north half of the Monadnock was completed in 1891, builders were confronting a question that had no clear answer: How high could load-bearing masonry go?For decades, architects had simply made walls thicker as buildings grew taller. The Monadnock pushed that idea further than anyone before it. At 16 stories, it became the tallest load-bearing brick building ever constructed and, in many ways, signified the end of an era.The design by Burnham & Root relied on a concept that was remarkably simple. There was no structural steel frame carrying the building’s weight. The masonry walls did the work.A lot of masonry. At street level, the exterior walls are about six feet thick. As the walls rise, they gradually taper, shedding weight while maintaining the strength needed to support the floors above. The building required an estimated 17 million bricks, all laid before modern layout equipment, spirit levels, or computerized engineering calculations became available.It’s one thing to discuss wall thicknesses and load paths on paper. It’s another to imagine the masons responsible for executing the work. Every course mattered. Every joint mattered. The tolerances that crews maintained over 16 stories still manage to impress engineers and preservation specialists today.The building’s appearance was equally unusual for its time. While many commercial buildings of the late nineteenth century relied on heavy ornamentation, the Monadnock put the brickwork itself on display. Long, uninterrupted wall surfaces and delicately curved corners emphasized the structure's mass rather than decorative details. More than a century later, the design still feels surprisingly modern.Yet even as the building demonstrated what masonry could accomplish, construction technology was changing. Engineers were beginning to embrace steel-frame systems that could reach greater heights without requiring massive wall thicknesses at the lower floors.The timing is apparent in the building itself.When the south half of the Monadnock was completed in 1893, it incorporated structural steel framing. Walk through the building today, and you’re looking at a snapshot of a major transition in American construction. One section represents the peak of load-bearing masonry. The other points toward the future of high-rise construction. For masonry professionals, the building’s original construction is only part of the story.The real test of any masonry system is time, and Chicago has supplied plenty of it. More than 130 years of freeze-thaw cycling, moisture exposure, settlement, thermal movement, and changing occupancy demands have worked against the Monadnock. Yet the building remains in service.That longevity has called for careful stewardship.Over the decades, preservation teams have addressed deteriorated mortar joints, localized brick damage, water infiltration, and facade weathering while maintaining the building’s historic character. Like many nineteenth-century masonry structures, the Monadnock was originally constructed with relatively soft masonry units and lime-rich mortars designed to accommodate movement and allow moisture to escape through the joints.That presents a challenge for modern restoration work. Matching mortar color is only part of the job. Preservation specialists have had to evaluate mortar composition, compressive strength, and permeability to ensure that replacement materials perform as well as the originals. Mortars that are too strong can trap moisture within the wall system or transfer stresses into adjacent brickwork, leading to cracking, spalling, and premature deterioration. Facade investigations have also provided a rare opportunity to study how a massive load-bearing masonry structure responds to more than a century of environmental exposure. Areas of weathering, movement, and previous repairs provide useful information for contractors working on historic masonry throughout the country. In many respects, the building functions as a full-scale laboratory for masonry preservation.The Monadnock also acts as a reminder that masonry performance is measured over decades, not construction schedules. Every repointing campaign, condition assessment, and repair project adds another chapter to the building’s history. For restoration contractors, suppliers, and consultants, few structures present a clearer record of long-term masonry performance under real-life conditions.More than a century after completion, contractors can still walk the building and study details that are impossible to replicate in a laboratory or classroom. The wall thicknesses, brickwork, mortar joints, and evidence of long-term weathering provide a direct connection to the construction practices of the late nineteenth century. In an industry where performance is ultimately measured in decades, the Monadnock remains one of masonry’s most instructive projects.About: American Treasure
