Abstract: Ceiling tiles and a moisture detection system in which an array of electrodes placed preferably on the top unseen surface of the ceiling tiles typically used in commercial-type buildings. A detection or controller circuit then monitors the electrical characteristics of these electrodes for any changes that would be indicative of water formation on the ceiling tiles. Generally, current will flow between the electrodes only in the presence of water or some other conducting fluid. When this current is detected, an alarm, for example, can be generated to notify security monitoring personnel to investigate the possible existence of water intrusion. Alternatively, coded signals can be generated at the ceiling tiles individually in the presence of water.