Rising damp is a common problem in older buildings, particularly those with solid brick walls. It is caused by water from the ground being drawn up into the wall through capillary action. If left untreated, rising damp can cause significant damage to the wall, including the growth of black mold and the decay of timber. Synonyms for rising damp include "capillary moisture," "groundwater infiltration," "damp walls," "waterlogged walls," and "wet masonry." It is important to address any issues with rising damp promptly to prevent further damage to the building and potential health hazards from mold growth. Professional advice and treatment may be necessary for severe cases.