This study evaluates ATP bioluminescence as a screening indicator for deterioration of ceiling gypsum boards affected by water leakage. Two field investigations of in-service ceiling boards showed that stained areas exhibited higher ATP values and lower maximum load in three-point bending than adjacent sound areas. Ring-shaped stains showed non-uniform ATP values within the ring, and amplicon sequencing suggested bacterial community differences between the rim and inner region. In a leakage exposure test, ATP values aligned with maximum load decreases more clearly than appearance-based brightness differences. Overall, ATP bioluminescence can potentially support non-destructive ceiling diagnosis by identifying areas suspected of deterioration.
