What is Penetrating Damp?

Penetrating damp, also known as lateral damp or rain penetration, refers to the presence of moisture or water that enters a building through its walls. It occurs when water from outside sources, such as rainwater or groundwater, infiltrates through the external walls and seeps into the internal areas of a structure.

Penetrating damp can be caused by various factors, including:

Defective or deteriorated external walls: Cracks, gaps, or holes in the external walls can allow water to penetrate the building. This can be a result of poor construction, lack of maintenance, or natural wear and tear over time.

Faulty roof or guttering: Leaking roofs, damaged or blocked guttering systems, or improperly installed or maintained downpipes can direct water towards the walls, leading to penetrating damp.

Porous building materials: If the external walls of a building are constructed using porous materials that readily absorb water, such as certain types of bricks or stone, they are more susceptible to penetrating damp.

Inadequate or damaged protective measures: Insufficient or damaged external protective measures like render, cladding, or sealants can fail to provide an effective barrier against water infiltration, allowing dampness to enter.

Signs of penetrating damp may include damp patches or stains on internal walls, peeling or flaking paint or wallpaper, a musty odor, and visible signs of water ingress. If left untreated, it can lead to further structural damage, decay, mold growth, and potential health issues.

Addressing penetrating damp typically involves identifying and rectifying the underlying cause. This may involve repairing external defects, improving drainage systems, applying water-resistant coatings or sealants, or employing damp-proof membranes. In more severe cases, professional assistance from a damp specialist or building professional may be necessary to diagnose and resolve the issue effectively.