At some height every wall must be laterally supported at vertical intervals with floors and roof or at horizontal intervals with cross walls, end walls, pilasters, buttresses, or columns. How tall can you build a single-story masonry wall before you need to brace it? The maximum height and slenderness of a masonry wall depends on what code is followed to design it. ANSI A41.1, an empirical code first published in 1944 doesn't allow a masonry wall to be higher than 20 times its thickness. ACI 531, a rational design code for concrete masonry first published in 1979, doesn't allow reinforced walls higher than 36 times their thickness and nonreinforced walls higher than 20 times their thickness. In 1988, the American Concrete Institute (ACI) and the American Society of Civil Engineers (ASCE) approved a new building code for concrete and clay masonry, ACI/ASCE 530. ACI/ASCE 530 allows masonry walls to be designed by empirical or working stress methods. When the working stress method is used, the new code does not limit the height-to-thickness (h/t) ratio of the walls. Depending on the code they must follow, designers can use empirical design, working stress design, or ultimate strength design. If they use empirical design, they must observe h/t limits. If they use working stress or ultimate strength design, there are no h/t limits.