A series of air permeance tests were performed on test panels constructed of clay brick and mortar according to ASTM E2178-11: Standard Test Method for Air Permeance of Building Materials. Four sets of brick were included in the test which represented a range of brick configurations. Typically, very low values of air permeance were measured on the test brick panels. A maximum material permeance of 0.012 l/(s m²) was measured at 75 Pa for one of the test groups while the material permeance was less than 0.002 l/(s m²) at 75 Pa for the other three test groups in this study. Typically, pressure differentials greater than 150 Pa were required to produce a flow rate greater than 0.002 l/(s m²) for these test panels. In addition to the masonry system permeability tests, a series of material permeability measurements were made using ASTM C577: Standard Test Method for Permeability of Refractories on the individual components of the masonry system. These material permeability measurements were related to the physical properties of the individual materials and the permeability measurements of the test panels evaluated by ASTM E2178-11.