Windows are a key part of the building enclosure, but they are also the costliest, most fragile, and worst thermally performing component. We will present on windows from our viewpoint as building enclosure consultants and forensic failure specialists. We will explore energy and comfort impacts of glazing and glazing ratios, and then move on to water control detailing and the window-to-wall interface. Covered topics will include sill pan and rough opening flashings, “innie” vs. “outie” windows in thick walls, two-stage joints and drainage, air barrier detailing, condensation problems, and window water leakage testing. We will also discuss storefront and curtain wall glazing systems and their associated detailing.