A non-destructive study was conducted on the 13th century caravanserai of Agzikarahan in Aksaray, Turkey, suffering from problems of seasonal rising damp in its lower parts. Both infrared (IR) thermography and a levelling survey were used for determining whether or not a surface-water drainage system was incorporated into its original construction and what its existing condition was. A map of its immediate periphery was produced, indicating overall slopes and local falls in reference to overhead roof drainage components. Damp zones of the grounds were mapped and neighbouring walls, as well as any underground drainage path or pipeline, were detected by IR thermography. Results showed that rising damp problems were associated with inadequate site grading and reverse falls in some areas around the building. Conditions for a satisfactory drainage were pointed out and occasional re-grading of the surrounding grounds as a preventive measure against ponding were suggested. The joint interpretation of IR thermography and levelling survey results provided a good combination for examining sub-surface and surface-water drainage systems and enhanced the accuracy and effectiveness of the survey. (c) 2004 Elsevier Ltd. All rights reserved.