Part 3: Flash a Nail-Fin Window in a Wall With Exterior Rigid-Foam Insulation
Mask off the window to keep things clean before using liquid flashing to seal the window flanges to the wall.
With the window in but the rigid-foam insulation still not installed, it’s time for the final flashing work, which will tie the window and its nailing fin to the waterproof window bucks, which are also connected to the water-resistive barrier (WRB). This phase of the install will again use Zip System Liquid Flash, just like the rough opening. To keep excess Liquid Flash from getting on the window, builder Jake Bruton applies painter’s tape all around the four sides of the window to protect it. When applying this tape, you do not want to cover the entire side of the window; it is important to leave a little bit of the main substrate of the window open because the goal of this flashing is to bridge the connection from the side of the window, over the flanges, and out onto the previously applied liquid flashing. You will hear Jake talk about making sure the connection between two substrates is secure quite often in this episode and the rest of the series. That is because these are the most worrisome areas for any builder—but as long as you do as Jake does and make sure everything is covered, connected, and flashed, your window will be protected. After the liquid flashing is applied, Jake recommends waiting until the liquid flashing is completely dry before removing the protective painter’s tape in order to avoid taking some liquid flashing off of the window along with the tape, which would require a patch-up job. Then, bring the foam back and put it in place, using seam tape to seal the seams while being sure to leave a little room at the top and bottom, so any water that may get into the window opening has a place to exit.