I am working on a water feature formed out of cast-in-place reinforced concrete with a hot-fluid-applied waterproofing system over the concrete. To protect the waterproofing, we plan to install shotcrete over it. What minimum thickness of shotcrete is required? Would welded wire fabric or fiber mesh be required as well?

In general, we would recom­mend a minimum of 2 in. (50 mm) of shotcrete. Either fibers or wire mesh or both should be used in this application. Please note that there are different types of synthetic fibers (microsynthetic and macrosynthetic). Refer to ACI 506.1R for information on fiber-reinforced shotcrete.

If the surfaces are steep or vertical, wire mesh should be used, but provisions need to be included to stabilize the wire mesh. This would likely require attachment points through the waterproofing system.