This detail illustrates a masonry window head condition. The concrete masonry backing is treated with blocking at the perimeter of the opening which is wrapped with transition material, which in turn engages with the air/moisture/vapor barrier in the field of the wall providing continuous resistance to air and moisture. Continuous insulation offers excellent thermal control. An optional cavity drainage insert protects the weep vents at the bottom of the cavity from becoming obstructed. The detail incorporates a vertical brick expansion joint and a vertical control joint at the block backing. The loose steel lintel is protected with thru-wall flashing returning vertically at each end termination to form an end dam. The durable drip edge guards against moisture reentry and may be notched to avoid excessively thick laps. Firestop material may be used behind the lintel if required by code.