47.5 MB - The Whole Building Design Guide

Stem wall foundations: Stem wall foundations have a continuousperimeter grade beam, or perimeter foundation wall, that is backfilledwith compacted earth to the underside of the concrete floorslab (see Figure 2-25). Because this foundation type is backfilledand has no crawlspace, hydrostatic pressures are minimized. Stemwall foundations are designed to come in contact with floodwaterson the exterior. They are more stable than perimeter wall foundationswith crawlspaces, but could experience structural damage ifundermined by local scour and erosion. Designs must account foranticipated debris and ice impacts, and incorporate methods andmaterials to minimize impact damage.Figure 2-25:Typical stem wallfoundationColumns or shear wall foundations (open foundations): Open foundationsconsist of vertical load bearing members (columns, piers, pilings,and shear walls) without solid walls connecting the vertical members.Open foundations minimize changes to the floodplain andlocal drainage patterns, and the area under the building can beused for parking or other uses (see Figure 2-26). The design ofthe vertical members must also account for hydrodynamic loads2-60 MAKING CRITICAL FACILITIES SAFE FROM Flooding