We are working with an architect in New York City on an unreinforced masonry (URM) building where they want to remove brick to provide a larger storefront opening. I would like to use the remaining walls to resist lateral forces but the brick is insufficient. We would like to remove one width of brick and apply 4 in. (102 mm) of reinforced shotcrete in its place. Can you tell me where I can find applicable code and design guidelines for this application?

Your proposed solution is certainly reasonable and is used regularly. Shotcrete has been used to strengthen both URM and tilt-up panels to accommodate enlarged openings. Shotcrete is a method of placing concrete and the in-place properties would be the same. The applicable code would be the code you would use if you were to strengthen this wall with concrete. Designs using the ACI 318 Building Code and Commentary are fully applicable to shotcrete placement, although compressive tests for acceptance are secured using cores from shotcrete test panels per ASTM C1140/C1140M and C1604/C1604M, rather than cast cylinders.