Please find enclosed picture for discussion. My concern is the wood in the cavity in ceiling is not protected which is an ordinary hazard type 1. The picture enclosed shows the sprinkler head below the combustible materials. From experience with a Engineering Firm in Vancouver with a wooden pier and wood combustibles the sprinklers in the mentioned drawing should be installed above the wood joists. Problem being with the wood right tight to ceiling you are running into such problems as beam codes and having to use to many sprinklers for the mercantile class being sought. As the mercantile is ordinary hazard type one needing 130 square foot spacing only in the cavity the joist should be stationed 2 to 3 inches below the top of the ceiling giving a 1 inch clearance from ceiling to top of sprinkler head deflector. Suggestion semi recessed head. By doing this the criteria for light hazard and ordinary hazard are covered.
I am very sorry I was removed from this job and had no time to speak to the city inspector in regards to this simple matter which needed a discussion with the architect of this job.