When it recently relocated to a new high-rise in downtown Charlotte, N.C., architecture and engineering firm Little didn’t just move into a new space; it created a new experience by designing its own flexible, attractive, and sustainable space, which is pursuing LEED and WELL Silver certifications.

The new office occupies the 14th, 15th, and 16th floors of the building. And connecting all three floors is an open, internal staircase that acts as a focal point and an architectural center of gravity. With the stair connecting all three of Little’s floors, the team was able to remove the mildly reinforced concrete slab and a 21-in. mildly reinforced concrete beam at two levels, which totaled 28 tons of concrete—more weight than the stair itself.

Instead of being traditionally anchored and reinforced at the lowest level, which would disturb existing tenants on the 13th floor below, this 15-ton stair hangs from a four-pronged structural mast anchored to the underside of the building’s 17th floor. The four-pronged structural mast distributes the load of the stair to the underside of the 17th-floor beams with bolted steel channels and transfers some of the load to the 16th and 15th floors, allowing the existing structure to adequately carry the appropriate load as required by code. Approximately 55% of the dead and live loads are carried by the 17th floor, while the 16th and 15th floors support the remainder of the load transferred from the inside HSS14×4 stringers. The mast connection to the 17th floor is accomplished by four 2¼-in.-diameter pins, and was used to eliminate the transfer of any moment into the existing structure while also complementing the rawness of the design.

Read more about this IDEAS² Award-winning project.