NFPA 13 2013 Ed. Section 8.15.14 (1) (a) "In light hazard occupancies where sprinkler spacing (either spray or old-style sprinklers) is less than 10 ft x 10 ft, a minimum clearance of at least 18 in. shall be provided between the sprinkler deflectors and the upper surface of the open-grid ceiling."
In the quoted section above, is this a hard limit of 10 ft max in any direction, or is this a limit of 100 square foot per sprinkler? For example, could the sprinklers be spaced 8 ft in one direction and 12 ft in the other (96 Sqft per head)? Or would this bump you into the next category requiring 24 in. clearance regardless of the sprinkler area per head?