Q: Almost all of the outdoor concrete balconies we build have puddles on them from time to time. These puddles sometimes draw complaints from general contractors or developers. When are puddles normal, and when do they amount to construction defects?
A: The 2006 version of ACI 117 mandates that balcony slopes must be measured within 72 hours of the pour and before the supporting shores are removed. ACI 117 goes on to define the amount of slope variation that is acceptable.
After the 72-hour window, and after removal of the supporting shores, the slab’s profile will change due to external forces, including dead loads, creep, curling, and shrinkage. Generally, the concrete subcontractor is not responsible for the effect of these forces on the slab. In fact, the ACI 117 commentary states that the purpose of the 72-hour window is to “avoid any possible conflict over the acceptability of the floor.” So without measurements taken within 72 hours following the pour, the complaining general contractor or developer has no objective proof of a problem with the slope.
Just as important as the ACI standards are the applicable plans and specifications in the contract documents. Architects often call for a 1% slope (1/8 inch per foot) on outdoor balconies. But this minimal slope does not provide sufficient drainage. Generally, positive drainage requires a slope of at least 2% (1/4 inch per foot). If the architect required a 1% slope and that is the slope you poured, within the 72-hour window and before the shores are removed, the general contractor and developer have no grounds to complain.
Lastly, you should consult the applicable local building code to see if it speaks to the maximum length of time deemed acceptable for puddles to remain on an outdoor balcony before evaporating. For example, the commentary in the 2001 Florida Building Code cites the National Roofing Contractors Association’s “Roofing and Waterproofing Manual,” which says that puddles on a roof should dry within 48 hours under ambient conditions. So if the balcony extends partly over conditioned space (that is, it also serves as a roof) and the puddles dissipate within two days, you could use this to your advantage in a dispute with the general contractor or developer.
Remember that in a dispute over the correctness of balcony slopes, puddles in and of themselves are not proof of a defect.
This answer was provided by Michael L. Forte, a partner in the Tampa, Fla. office of Rumberger, Kirk & Caldwell, P.A. He is an attorney who defends contractors and subcontractors in construction defect lawsuits.
