Window buck installation tips and tricks
Flashing a Bucked Window
In this video, Williams demonstrates how to buck a window for exterior insulation in a new construction home with a focus on critical flashing details. In a step-by-step process, he explains:
- How to size the rough opening to accommodate a buck made of 2x4s, which is sealed and flashed starting at the sill and working up the sides and top.
- Next, a stretch-style flashing tape is applied to the sill pan. A window can then be installed following the manufacturer's guidelines.
- Finally, a metal head flashing is integrated that runs behind the WRB, over the buck, and down the window frame. Then, the assembly is ready for exterior insulation.
How to install XPS foam insulation around an existing window
This video details the installation process for XPS foam insulation in an existing wall assembly.
- Starting with a properly flashed 400 Series Casement Window, Williams walks through the importance of a properly constructed window buck, which aligns with the insulation pane and provides a surface for trim attachment while ensuring no fasteners penetrate the window flange.
- Another key feature is the sloped sill, which is made of the same material as the buck and directs water away from the window.
- The final step he details is installing a window head flashing, which protects the top of the window buck and trim, and leaves the assembly ready for foam, strapping, and siding.
Meet Randy
Randy Williams started his construction career in the mid-1990s installing electrical, plumbing, and HVAC systems with his brother. In the early 2000s, his family branched into building and renovating homes. By 2005, Randy was working full time as a general contractor. He furthered his education in 2009 becoming an energy auditor. Today, Randy works with other contractors, homeowners, and utilities performing energy audits, building diagnostics, energy design, and code compliant testing, and assisting in the design of energy-efficient homes. He is also a contributing author to several trade publications and occasionally teaches home diagnostic testing and building science topics at different trade shows and training events.


