With window flashing done, the next step in any window installation is to air-seal and insulate. This work happens from the inside, and is the same regardless of water-resistive barrier (WRB). In this video, builder Jake Bruton walks through the theory of air-sealing and insulating, its importance to the overall function of a window installation and the comfort of the home, and the materials and methods needed to do the work well. Highlights include tips about how much foam to spray into the gap between window frame and rough opening, and how to tackle problematic details, like air-sealing around shims.