If you’re putting in new construction style nail fin windows, just follow these three easy steps and you will hit a home run every time.
In these photos we are putting in an all vinyl single hung window into a wood shop we built, but the steps will be the same for clad windows.
Prep The Opening
The first thing to do is check the window R.O and make sure the opening in the wall will work. After you’re sure about that, cut two small slits in the top corners of the Typar and fold it up out of the way. Put a staple in it to hold it there for the time being.
Next cut a piece of sill protector wrap to 8“ longer than the opening width. If you use the 8“ wide rolls of this wrap, it will work out so you can fold the wrap over the front edge of the sill. Take a small piece of the wrap and put it in the cut you make at the bottom corners to keep the drainage plane correct. Unpack the window and set it next to the opening.
Install The Window
This is a two person job. Set the window into the opening and make sure the nail fins are all tight to the wall. The inside person will then center the window in the opening allowing space aground all sides for insulation. The outside person will take a level and set the bottom of the window. We like to have a shim at each corner even if the window is level to allow room for insulation. Nail off the bottom flange of the window.
Next, check the window for square by checking the diagonal measurements. Shim the window square and then nail off the rest of the nail fins.
Seal The Window
After the window is nailed off, you need to seal the window to the wall. We use a 4“ roll of window tape with a foil face and waterproofing membrane on the back. Install the bottom flange tape first, then the two sides, then the top flange tape making sure to overlap the pieces creating a water tight seal. Now fold down the Typar at the top over the top window flange and tape the two cuts you made. On the inside, seal the window jamb to the framing with window and door spray foam. Be careful not to overfill the space as the foam will expand.