Rising damp in masonry walls and the importance of mortar properties

This paper briefly reviews the rising damp phenomenon with a discussion of the controlling mechanisms and contributing factors such as capillary effect, water absorption, evaporation and salt formation. It also presents the results of a study on rising damp based upon a practical year-long test. Measurements were made on rising damp on walls made from different mortars and the observations were compared with theoretical models. It was found that mortar characteristics would significantly affect the height of rising damp. It was also observed that there was a strong correlation between rising damp and the Sharp Front Model, and the rate of absorption of water into the mortar was a key factor in determining the height of the rising damp front. In addition, walls with rising damp treatment are warmer than their control counterparts due to a reduction in surface moisture evaporative cooling.