When Tino Kalayil toured Pancratia Hall in Denver, he wasn’t just admiring a historic building — he was witnessing a case study on the longevity of concrete masonry.
Originally built in 1930 as a collegiate, Gothic-style dormitory, the structure has since been transformed into the Pancratia Hall Lofts, a 74-unit affordable housing complex. Its massive load-bearing walls—constructed of concrete masonry units (CMU)—have stood the test of time.
“There were very minimal dollars spent on repairing the masonry,” says Kalayil, a technical director with the Block Design Collective, an industry checkoff program providing complimentary building project services to architects and engineers. “That’s nearly 100 years of performance with almost no maintenance. That’s sustainability in action.”
A Better Block
Architects often associate CMU with utilitarian gray blocks, but Kalayil wants to challenge that perception. “It’s not your grandfather’s block anymore,” he says. “There have been significant advancements in durability, aesthetics, and performance.”
Modern CMU features defined strength and testing standards, is available in various densities, and can be finished in a range of textures and colors. Some are engineered for improved fire resistance, thanks to lightweight aggregate mixes that increase air content without sacrificing structural performance.
“Designers can achieve both structural efficiency and architectural expression,” Kalayil says. “It’s a vertical element that plays well with other systems and opens the door to creative applications.”
Durability for Generations
One of CMU’s strongest arguments is its durability. It is both pest resistant and, with minimal care, recovers quickly following exposure to water or humid conditions. It also provides passive benefits like thermal mass, helping to stabilize indoor temperatures throughout the year.
“From a fire resistance standpoint, you’re looking at up to four hours in some assemblies—often with no additional layers,” Kalayil notes. “That’s a significant benefit when designing for code compliance or occupant safety.”
CMU offers redundancy in design, as well. “You’re not just meeting code minimums—you’re often exceeding them,” Kalayil says. “That inherent resilience is a safety net.”
A Sustainable Choice
CMU contributes to sustainability on multiple fronts. The hollow-core design reduces the amount of cement—and, by extension, the embodied carbon—needed for production. Over time, CMU can also sequester atmospheric carbon, storing it permanently in the material matrix.
Moreover, CMU is highly recyclable. “It’s commonly crushed and reused as road base or aggregate,” Kalayil explains. “In a full life cycle analysis, that adds value.”
The local sourcing of block is another sustainability win. “Because CMU is typically manufactured near the jobsite, you’re reducing transportation emissions and supporting regional economies,” he says.
Despite these advantages, Kalayil says CMU is underutilized in residential and mixed-use design due to outdated perceptions and unfamiliarity with newer product lines. “We need to normalize it,” Kalayil notes. “This isn’t just a material for schools or warehouses. It can and should be used where performance matters—especially in fire-prone or disaster-prone regions.”
Resilient and Future-Ready
Beyond design and construction, CMU may offer long-term economic advantages, as well. Kalayil points to the rising cost of insuring buildings—especially in disaster-prone areas.
“Masonry structures are seen as lower risk,” Kalayil says. “Insurers know they’re less likely to face costly claims.”
Whether measured in fire resistance, thermal performance or simple longevity, concrete masonry is proving to be one of the most future-ready materials available.
“Pancratia Hall is proof,” says Kalayil. “A building that served one generation, a century later, now is ready to serve yet another generation. That’s what sustainable architecture really looks like.”
Whether you’re designing for durability, fire safety or long-term sustainability, concrete masonry offers unmatched performance and design flexibility. The Block Design Collective provides free nationwide support for architects, engineers, and builders working with CMU. Available at blockdesign.org, experts can help answer a broad spectrum of concrete masonry questions, from energy modeling to structural design.
