All building materials change in volume due to external or internal stimuli. When these movements are restrained, cracking often occurs which can lead to water infiltration, efflorescence, unit failure, deterioration of interior finishes, or generation of mold in the wall system. To avoid cracks in masonry, movement joints must be properly installed.
There are distinct differences between movement joints that are used to construct masonry walls and those used in clay masonry walls. Expansion joints are used in clay wall masonry walls while control joints are used in concrete masonry.
For a detailed discussion, see Field Notes; Movement Joints
, by Jake Ribar, principal masonry evaluation engineer, CTLGroup, Skokie, Ill.