Solving damp problems

In older buildings, damp is frequently the result of modern materials and alterations that disrupt the way the original fabric manages moisture. Traditional walls and finishes rely on some movement of moisture — or being able to “breathe” — so impermeable repairs or finishes can prevent drying and create or worsen damp. Although people often label any visible damp as “rising damp,” many problems are actually caused by penetrating damp, and an increasing number stem from condensation as buildings are made more airtight and better insulated.

 

Penetrating damp can be misleading because water may travel through masonry or timber from the actual point of entry before it shows as a stain. Common causes include missing or broken roof tiles, failed mortar joints, rotten window sills, blocked or leaking gutters and downpipes, high external ground levels, poorly executed junctions between roofs and parapets, and even internal plumbing leaks. The situation is often made worse by complex, impermeable cement renders or pointing that trap moisture rather than letting it escape.

 

Modern interventions can also create new problems: impermeable paving or hard landscaping that butts directly against a wall, or the pouring of a concrete floor slab inside an older building, can block natural drying paths and force moisture to move into the walls. Because of this, the most effective approach is usually to identify and rectify the source of moisture — repairing roofs, gutters, drainage, ground levels or plumbing, and using compatible, breathable materials — rather than relying solely on injected damp‑proof courses or other modern quick fixes.