hollow floor tiles after water damage - living the bump
if excess moisture is present during the curing phase either in the form of excessive humidity or water damage from a flood the mortar will not bond with the tile and leaves hollow-sounding tiles behind. tile that has properly bonded with mortar that has been allowed to cure should rarely become hollow as water does not generally affect cured concrete (as the underwater piers and docks of the roman empire still whole and durable under the mediterranean and other bodies of water