What does ACI 302, “Guide for Concrete Floor and Slab Construction,” recommend for sloped surfaces?
Before bidding the resurface project, it’s important to see if the original floor was properly designed and installed. One of the primary causes for low spots or poor drainage is inadequate slope. Section 11.10 of ACI 302 states, “puddles or birdbaths on an outdoor concrete slab after a rain, or on a floor after hosing, characterize poor slab or floor surface drainage or serviceability.” However, the minimum slope recommended (1/16 inch per foot) for interior floors is not sufficient to promote free drainage. A slope of ΒΌ inch per foot enables water flow. Another primary cause listed in 302 is “failure to frequently check grades, levels, and slopes with long straightedges, and to properly build up low spots in areas detected.” This recommendation implies that concrete surfaces can be finished without any low spots. As discussed above, this is an unrealistic expectation; standard tolerances should apply. Question: Are birdbaths only caused by finishing? Answer: Of course not. Advise the
