Insulation placed in the exterior air cavity between brick veneer and a backup wall is now common practice; however, accounting for the reduction in thermal performance as a result of thermal bridging at brick ties is not. As the building enclosure’s actual thermal performance becomes more important and integrated into the overall design of other building systems, a clear understanding of thermal bridging and its impact on effective R-values is needed. Brick ties are only one example of a thermal bridge in the building enclosure, but a close look at their significance illustrates how important it is to account for thermal bridging.