Cracks may indicate structural problems in constructions made of timber beams, but their identification in notably roof constructions is difficult. Therefore this paper presents an algorithm for the automatic detection of cracks in timber beams sampled by LiDAR data. This algorithm enables the identification, analysis and monitoring of cracks and their geometrical characteristics. The algorithm is validated by tests on laboratory specimens and on a timber roof structure. The results prove that the proposed algorithm is able to automatically identify and analyze cracks with a width of above 3 mm from point clouds with an average resolution below 1 mm.