What do control joints in masonry walls help prevent?

Control joints in masonry walls are specifically designed to manage and alleviate stresses that can lead to cracking. As temperature changes and moisture levels fluctuate, masonry materials expand and contract. If these movements are not controlled, it can lead to stress accumulation in the material, resulting in cracks. By incorporating control joints, these movements are effectively managed, allowing for controlled areas where the wall can flex and preventing potential cracking that might emerge due to unusual stresses like thermal expansion, settling, or shrinkage. This proactive design feature ultimately enhances the longevity and integrity of the masonry structure.