COLUMN BUILDING SCIENCES FIGURE 1 Basement foundation, crawlspace foundation and crawlspace foundation with a " cripple " wall. Note in all three foundations the connection of the continuous exterior structural wood sheathing (plywood or oriented strand board-OSB) to the foundation sill plate. Further note the connection of the foundation sill plate to all three concrete foundations. FIGURE 2 Interior posts and piers require additional bracing in both crawlspace assemblies by installing cross bracing. All three foundation types should also have solid blocking between floor joists. The solid wood blocking prevents the floor joists from " racking " or rolling sideways. diaphragms are connected and in turn are connected to the foundation anchors. Building bracing is typically provided by the use of continuous exterior structural wood sheathing (plywood or oriented strand board-OSB). Note that the crawlspace foundation with a " cripple wall " has structural wood sheathing on both sides. Additional bracing is provided in high earthquake risk regions such as California: basement foundations, crawlspace foundations and crawlspace foundations with " cripple " walls. Note in all three foundations the connection of the continuous exterior structural wood sheathing (plywood or oriented strand board- OSB) to the foundation sill plate is a big deal. Further note the connection of the foundation sill plate to all three concrete foundations is also a big deal. In this manner the wall-to-fl oor in both crawlspace assemblies by installing cross bracing at interior posts and piers (Figure 2). All three foundation types should also have solid blocking between fl oor joists. The solid wood blocking prevents the fl oor joists from " racking " or rolling sideways (Figure 2). Basement Foundation Figure 3 illustrates the environmental separation aspects of basement foundations. A continuous water control layer controlling rainwater is installed on the exterior of the wall structural sheathing and is connected to the continuous water control layer on the exterior of the basement foundation. A continuous air control layer is installed on the exterior of the wall structural sheathing and is connected to the concrete foundation wall, which is acting as the foundation air control layer. Vapor control is provided by controlling the temperature of the wall assembly condensing surface by installing continuous exterior insulation. Vapor control of the concrete foundation is provided by installing dampproofi ng on the exterior of the foundation wall and a sheet of polyethylene under the foundation slab. Thermal control is provided by installing continuous exterior insulation and cavity insulation on and in the wall framing. Additionally, rigid insulation is installed on the interior of the foundation wall. This approach works in all climates. Crawlspace Foundation Figure 4 illustrates the S E P T E M B E R 2 0 2 2 ashrae.o rg ASHRAE JOURNAL 53https://ashrae.org/