Pentagon Centre Building C is located at 15th Street and South Hayes Street in Arlington, VA. The scope includes Type I-A construction of a 10-story cast-in-place concrete high-rise with 253 market-rate apartment units. Scope also includes over 16,500 square feet of retail, and a 121,417 square foot below-grade parking garage with 252 spaces. This new community is located on a tight urban site and requires a large complex utility relocation at Hayes Street. For this project team of building scientist installed an air barrier system.  An air barrier is a system that’s designed and constructed to control air flow between a conditioned space and an unconditioned space.  Air barrier systems solve common building environment problems by creating a seamless moisture barrier with no tears, holes or “mis-lapped” joints, effectively blocking air leakage, and reducing energy costs and the risk of condensation in the wall. Air barriers also protects sheathing and rough openings from weather damage during and after construction. Additionally, air barriers provide the opportunity for pressure-equalized or pressure-moderated wall design. This minimizes the risk of rainwater penetrating through any type of wall assembly.