WDP worked alongside a MEP consulting firm that provided an energy analysis of the terminal building and estimated the cost and energy savings for the envelope repairs proposed by WDP. These repairs require the replacement or significant modification of building envelope assemblies totaling over 90,000 square feet of cladding.
Through a rigorous building enclosure qualification selection process, WDP was awarded the investigation and repair services for this airport terminal building. A comprehensive investigation of the building enclosure was performed, specifically to diagnose systemic air and water infiltration and stone masonry veneer stability issues. A number of design and construction deficiencies were identified with all three major cladding systems on the terminal building, which are natural stone masonry veneer, insulated metal panels, and glazed curtainwall systems. In addition to diagnostic water testing to identify water leakage mechanisms, the investigation included exploratory test cuts through the masonry veneer, exploratory removal of curtainwall trim and pressure plates, material sampling and laboratory testing, and deployment of temperature and relative humidity datalogging instrumentation to accompany a building science investigation and inform subsequent hygrothermal models.
During the repair scope programming phase, WDP identified areas of stone veneer masonry that had become unstable to the point that emergency stabilization measures were necessary. We worked closely with the airport authority to evaluate a range of emergency measures to limit the impact on airport operations and security. Ultimately, temporary debris netting attachments were designed to restrain unstable veneer to the underlying structure until long-term repairs could be executed.
Due to the prevalence of issues observed throughout the exterior enclosure and cladding assemblies, particularly at interfaces between cladding systems, all stone veneer and metal panels are to be completely demolished, as well as their backup framing systems—which were often incorrectly installed. New light gage framing backup is being designed to transfer design lateral loads to the existing structure. New batt insulation, sheathing, and a continuous air barrier will be provided with robust cavity closures and transition details. The total thickness of insulation varies from location to location, but in all cases, additional insulation is to be provided to improve the thermal resistance of these systems to meet or exceed current energy code. WDP staff are well-versed in building science principles, and given the increased insulation and improved airtightness, hygrothermal analyses were performed for each assembly to verify the long-term durability of each. There is significant complexity in modifying existing wall assembly thicknesses to accommodate additional insulation and new drainage layers for water management redundancy, but WDP’s vast experience with repairing and upgrading existing structures has allowed us to develop creative solutions to complex problems.
ServicesBuilding Science & Enclosure Consulting
Rex A. Cyphers, P.E., Principal, Chief Operating Officer
Metropolitan Knoxville Airport Authority