We recommend the use of EPS Bucks (manufactured by FoxBlock) as they provide R-12 insulation value as well as provide multiple attachment points on the interior face (for inset windows) and on each edge (for surface mounted windows).
An excellent installation video by FoxBlock for surface mounted windows can be found here.
ZEEs are used to strengthen and ensure window bracing is at 90 degrees. For a printable PDF, click on the image.
When the windows or doors are extremely heavy, it may be necessary to cut openings in the vertical bucks so that the window or door has direct contact with the concrete. Speak with your door or window manufacturer to obtain loads.