There are many acceptable ways to mount and detail windows for support and weather resistance. This QuickGuide provides window installation instructions based on research conducted on walls with continuous insulation.
- ABTG Research Report: Installation and Performance of Flanged Fenestration Units Mounted on Walls with Foam Plastic Insulating Sheathing
- ABTG Educational Program: Window Installation Methods for Frame Walls with Foam Sheathing
Four typical methods for window framing:
These following installation methods are covered in ABTG's Educational Program. These methods include windows with integral mounting flanges and all use taped foam sheathing as the water resistive barrier.
Standard Method: Covers the most common method of flanged window installation over foam sheathing where the flanges are mounted directly over up to 2" of foam sheathing.
Picture Frame Method: Covers a “picture frame” concept with window flanges mounted to the picture frame. Commonly used with foam thicknesses of 3/4 inch to 1-1/2 inches to match common lumber dimensions.
Window Buck Method: Covers a “window buck” concept with window flanges mounted directly over foam sheathing. Most common for walls with more than 1-1/2 to 2-inches of foam sheathing.
Rainscreen Method: Covers a “rainscreen” concept with window flanges and furring mounted directly over any thickness of FPIS.