Control Joint

Category: infrastructure

A continuous vertical planned weak point built into a CMU wall to manage shrinkage cracking.

Concrete masonry units naturally shrink slightly as they fully cure over time. A vertical control joint incorporates a clean vertical split through the block layout filled with flexible caulking instead of mortar, channeling the natural shrinkage cracks to a neat, straight line.

Common Examples

• We detailed vertical control joints every twenty linear feet along the block perimeter to completely eliminate erratic shear wall cracking.
• Never run structural horizontal joint reinforcement across a control joint, or you will bind the gap and cause cracking nearby.