- Question: The 1988 Uniform Building Code (UBC) requires load-bearing stone walls to be at least 16 inches thick. Does this mean natural stone can't be used in cavity bearing walls? Most stone has much greater compressive strength than brick or concrete block.
Answer: This minimum thickness requirement is in the empirical design portion of the UBC, which is used in lieu of rational design. The code does not give any guidance for rational design of stone masonry. Its discussion of allowable stresses applies only to clay and concrete masonry.Therefore, to use stone in cavity wall construction, you must determine allowable stresses through testing. You also can design the wall as a veneer wall in accordance with UBC's Chapter 30 on veneer. The main difference between designing it as a veneer wall or a cavity wall is how you distribute stresses. In a veneer wall, all loads are assumed to be carried by the structural backup. In a cavity wall, some of the loads are shared by the stone face. In both cases you must make sure that the stone face is adequately tied to the backup.