Penetrating Damp Treatment

Penetrating damp occurs when water enters a building from the outside, often through leaks, damaged gutters, roofs, or cracked walls.  

Rising damp is caused by groundwater moving up through walls via capillary action, usually due to a defective or missing damp-proof course (DPC). The height and source of the damp help distinguish between the two. 

Signs of penetrating damp include damp patches on walls, black mould growth, wet rot affecting wooden fixtures, algae or moss on exterior walls, and white salt deposits (efflorescence) on brickwork. Damp that appears higher than one metre from the floor, or that worsens after rain, is usually a sign of penetrating damp rather than rising damp. 

Treatment focuses on stopping water ingress. This can include repairing roofs, gutters, windows, doors, and brickwork, applying waterproofing creams or membranes, and damp-proof replastering internally. External breathable water-repellent treatments can also prevent moisture from penetrating masonry. 

Penetrating damp can be very serious if left untreated. It spreads through porous materials like brick, plaster, wallpaper, and insulation, potentially damaging structural components, wooden fixtures, and interior finishes. Left unchecked, it can lead to mould growth, spalling, and long-term structural issues.

Costs vary depending on the extent of damage, the affected area, and the severity of the damp. Simple treatments, like applying a waterproofing cream, may be relatively inexpensive, while more severe cases requiring repointing, structural repairs, and damp-proof replastering will cost more. A professional assessment provides an accurate, tailored quote.

In most cases, home insurance does not cover penetrating damp. This type of damp is usually the result of building defects or maintenance issues, which homeowners are expected to manage and prevent through regular upkeep.