The geometric design of Phase I of this project results in an appearance of a three-sided glass pyramid with aluminum curtain wall mullions dead-loaded at the ground floor and spanning continuously through the roof. The building occupants experienced loud, gunshot-like noises emanating from the Southeast and Southwest elevations of the building, particularly on sunny days. CDC demonstrated that no provisions had been made for thermal movement at lateral restraint anchors located at floors 2, 3, 4 and the roof level. When thermal heat gain and loss on these sides of the building caused the mullions to expand during the day under heating conditions, then to contract at night when thermal gains reversed themselves, the overly tightened bolts and lack of slip shims at lateral restraint anchors caused mullions to bind against the anchors - resulting in the sounds.
CDC provided observation and documentation of installed conditions, monitored total thermal expansion at mullions, and developed a remediation procedure for implementation by the General Contractor for the project.