Description: Window and other Wall Opening Flashing presents special challenges. Flashing must function to protect these critical areas from water infiltration while accommodating thermal movement. Wall panel and flashing dimensions should be coordinated with penetration placement to provide for desired (generally symmetrical) layout. These details are meant to supplement 12.7 D. Typical Window Head and Sill
Ideally, fenestration flashing should be installed before the windows or door frames. This allows for the frames to rest on the flashing with a bed of sealant between. If frames are hollow or slotted, one may design the flashing edge to fit into this cavity, providing an additional barrier to water infiltration.
For smaller openings, Sill, Jamb and Head flashing pieces are often formed from one continuous longitudinal strip. If a multiple piece option is necessary, flashing pieces are commonly overlapped 4-6" with dual beads of sealant placed within the lap.
Symmetry: Exact Panel width and height rarely coincides perfectly with edges of the window penetration. The exposed dimension of sill or head flashing is often easier to change to suit conditions.
Options include, but are not necessarily limited to:
- Form panels with width more appropriate to actual coverage requirements.
- With standing or batten seam systems, spread some seams (slight flare at base of seam, up to ¼") for minor coverage adjustment. Do not try to compress seams together, as the flat of the panel may bow, causing exceptional oil canning while restricting thermal movement.
- Make some panels runs slightly narrower or position the narrow panel runs at building corners, directly at window jambs or directly above a penetration.
- Design with vertical battens at edges of window or door penetrations.
Substrate: Continuous Nailable Substrate
Fastening Method: Cleats screwed or nailed to substrate.
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