Q We are designing a five-story wood building on a podium slab with first-story concrete 1. walls (h=12 ft [3.6 m]). What is the recommended spacing between the contraction-expansion joints in cast-in-place walls? A First, we have to distinguish contraction joints—designed planes of weakness that 2. promote cracking of the wall at desired locations—with expansion joints—separations between adjacent sections of a concrete wall designed to allow free movement caused by thermal expansion, lateral loads, or differential movement of foundation elements. Contraction joint spacing may vary, depending on the wall type, use, and service conditions, from 15 to 0 ft (4.6 to 9.6 m). ACI 224.3R-951 recommends contraction joint spacing to be equal to the height of the wall for high walls (taller than 12 ft [3.6 m]) or three times the height of the wall for short walls (shorter than 8 ft [2.4 m]).
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