Caulking Between Walls & Window Wrap

Cover your window opening with house wrap. This can be done as the entire home is wrapped, or as a separate job during which only the new windows or other features are wrapped. Use your razor knife to cut a slot through the wrap down the center of the window opening, and cut a diagonal toward each corner. Bend the wrap around the edges of the window opening, and fasten it in place with your staple gun. Lift up the top piece of wrap, and apply a bead of caulk to the space between the wrap and the sheathing. Fasten the top piece of wrap in place with your staple gun.

Apply caulk to both sides of the window opening and the bottom. The caulk should coat the inside edge of the house wrap, so the window slides into the opening with a caulk seal already in place. The caulk will then spread along the sides and bottom of the window frame, reaching places impossible to access once the window has been installed.

Place your new window into the opening, and use your hammer and nails to fasten it in position on all sides. Seal all the edges with more caulk. The caulk should fill any gaps along the two sides, and the top. Install a piece of metal flashing along the top edge of your window frame, using your hammer and nails to fasten it to the sheathing. The flashing should sit directly on a bead of caulk and should run water away from the window and its edges, not toward it.

Use your staple gun to fasten a 6-inch-or-wider strip of window wrap on all four edges of the window. Insert the exterior window sash to cover the edges of the window, all the way around. Move inside and apply more caulk to any gaps around the edges of the window. Allow the caulk to dry, then move on with the interior finish.