Builder Jake Bruton demonstrates trusted window-flashing details for walls with the following water-resistive barriers: Zip System sheathing, exterior rigid-foam insulation, housewrap, peel-and-stick membrane, and fluid-applied WRB.
Use a piece of bevel siding and some carefully fitted pieces of Zip System tape to flash the sheathing to the framing.
Run a bead of sealant around the sides and top of the rough opening before setting, squaring up, and fastening the window to the framing.
Wrap the sides and head of the installed window with Zip System tape, but leave the bottom flange of the window untaped for drainage.
Spray foam and high-quality sealant bridge all of the gaps between the framing, shims, and window for a durable and energy-efficient installation.
Flash the sheathing around the buck to the window opening with tape or liquid flashing before installing the exterior foam insulation.
Use a manufacturer-approved type of sealant to bond the window to the preliminary flashing before setting, squaring, and fastening the window to the framing.
Mask off the window to keep things clean before using liquid flashing to seal the window flanges to the wall.
After installing the water-resistive barrier, cut the window opening and then use bevel siding and tape to create a positive-slope sill.
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