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
- DrJ Research Report: Attachment of Windows with Integral Flanges Through Foam Plastic Insulation Sheathing to Wood Framing
Four typical methods for window framing:
All installation methods shown below 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. [Installation Education]
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. [Installation Education]
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. [Installation Education]
Rainscreen Method: Covers a “rainscreen” concept with window flanges and furring mounted directly over any thickness of FPIS. [Installation Education]