Rising damp
Rising damp: moisture wicking upward from the ground into masonry walls. Prevented by a correctly installed damp-proof course (DPC) per NCC Housing Provisions 5.7.
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Rising damp is the upward migration of ground moisture into masonry walls by capillary action. Water is drawn up through the pores and joints of brick, block, or stone from the footing or soil below, carrying soluble salts with it. Visible symptoms include damp patches or staining on internal and external wall surfaces typically within 1 m of floor level, salt crystallisation (efflorescence), paint or plaster bubbling, and a tidemark at the moisture front. Left unaddressed, rising damp causes mortar deterioration, spalling brickwork, and internal lining damage.
The primary defence is a correctly installed damp-proof course (DPC) at the base of every masonry leaf, positioned at the heights specified in Housing Provisions 5.7.4. Where rising damp is present in an existing building, the cause is usually a DPC that is too low, bridged by mortar droppings or render, missing, or physically deteriorated.
Also known as: rising moisture, capillary damp.
Category: Masonry / waterproofing / defects.
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Last updated: 2026-05-10. Verified: 2026-05-10.