Installing a Nail-Fin Window Over Housewrap
As we add thicker insulation and more water-sensitive materials to the walls of our houses, it becomes increasingly important to detail our exterior walls to keep water out. Window flashing is one of the parts of a house where this matters most. Getting flashing details right for the common nail-fin-style window means making leakproof transitions between the water-resistive barrier (WRB) and the flanges that fasten the window to the wall.
In this Fine Homebuilding Shop Class video series, professional builder Jake Bruton demonstrates the crucial steps for getting the flashing details right when installing a flanged window in a wall covered in housewrap—in this case, Benjamin Obdyke Hydrogap. In the first episode, Jake prepares the opening in the wall by cutting through the Hydrogap and taping it back to the studs inside the rough opening. Next, he adds a bead of sealant before inserting, plumbing, squaring up, and fastening the window in place. The third episode outlines the methods for taping over the flanges to create the primary waterproofing details. Finally, he applies foam and sealant in the gaps between the window and the interior side of the rough opening to wrap up this airtight, energy-efficient installation.