Uses Structures and Retrofits A brief understanding of the different tenant Uses of buildings, Retail, Office, Industrial, Mixed Use, and Artist Lofts. Learn how to identify the different Structures available to your clients. Explanation of the history of commercial construction in California starting with the 1920’s URMS, RM, CMU, Tilt Ups, Steel and Concrete Examples of the fixes Retrofits required by city ordinances and lenders.