Principal research engineer, Experimental Building Station, Sydney, NSW
Pages: 17 Published: Jan 1982
Rising damp problems frequently are encountered in old masonry buildings where either there is no damp-proof course (DPC) or the DPC has broken down. Moisture in contact with the base of porous masonry walls moves upward by capillary action unless there is an effective barrier to prevent this movement. The moisture invariably contains soluble salts that are deposited near or at wall surfaces where evaporation takes place. Salt crystallization and the associated expansion can cause deterioration of the masonry and surface finishes. The dampness problem sometimes can be overcome by the insertion of a new DPC or by impregnation of the masonry with chemical solutions that form moisture barriers. Electro-osmosis, cementitious grouts, damp-proof mortars, and Knapen tubes also have been used to treat rising damp, but often do not provide an effective solution to dampness problems. Where damp walls are contaminated with salts, the treatment of rising damp alone may not prevent continued deterioration unless measures are taken to reduce the level of salt contamination.
rising damp, sheet damp-proof courses, chemical damp-proofing treatment, electro-osmosis, cementitious grouts, damp-proof mortars, Knapen tubes, moisture measurements, salt-damp attack
Paper ID: STP38690S