In practice, there are many different combinations of vertical and horizontal insulation details, R-values, and footing depths that can be used in an FPSF.

     The detailed design approach is a flexible approach that allows the designer to utilize experience and select the preferred method of construction for a given site. For example, the designer may opt to provide vertical wall insulation only, wing insulation only at the corners, or provide wing insulation around the entire building. The designer also has the flexibility to step the footing to increase foundation depths, add wing insulation to reduce required foundation depths, or select the width of wing insulation in meeting the minimum requirements in the design process.