My new pool is currently being tiled. I checked the quality of the installation by lightly tapping on each tile using a large steel nut and listening for any hollow sounds. The tiles appear to be tight and sound, no problems at all. Next, I tapped on the precast concrete coping and heard hollow sounds at each end of almost every piece of coping. I'm surprised because the installer used a rubber mallet to pound each coping piece into place until mortar would squeeze out the sides. I'm guessing he spread the mortar too thin at the ends.
I'll call the pool contractor tomorrow to get his opinion. Pulling all the coping off would delay the completion, especially if any pieces are broken in the process. The coping is custom made with a 3 week lead time. Has anyone experienced this before?