Our scope of work included the design review of the window-wall system at the south tower, which included the hotel and residential units.  Morrison Hershfield assisted the owner in selecting appropriate building envelope systems to minimize risk for the exterior wall assembly. Our prompt review of shop drawings helped with field review during construction, and field testing of the window wall system for water penetration resistance.

On the Lincoln Square projects both towers used a curtain wall system for the exterior envelope. The plane of the air barrier was extended from the podium roof to the starter track for the curtain wall system. At the level of the tower roofs the air barrier was transitioned from the curtain wall to the roof membrane. The two towers used different approaches to the air barrier for the curtain wall system based on the proposed occupancy. On the hotel/condo tower which has higher humidity levels and where the HVAC is driven by the occupants, a metal back-pan system was used in spandrel and opaque panels to move the plane of the air barrier inboard of the thermal insulation to keep the plane of air tightness inboard of the dew point thereby significantly reducing the risk of condensation. In the office tower with its lower humidity levels and automated HVAC system ensuring a higher rate of ventilation, a more traditional system was used with the plane of the air barrier maintained at the level of the spandrel panels. Nonetheless to minimize the risk of moisture damage an internal gutter was incorporate to capture any incidental condensation.