Penetrating Damp Repairs in Brighton & Sussex

Penetrating damp — sometimes called lateral damp — is caused by water entering through the external fabric of the building. Unlike rising damp, which travels upward from the ground, penetrating damp moves horizontally or downward through walls, roofs, and around openings. It can affect any floor of a property, not just the ground floor.

Sussex sits on the south coast of England and is exposed to prevailing south-westerly winds that drive rain directly against building facades. Solid-walled Victorian terraces in Brighton, flint cottages across the South Downs, and rendered coastal properties in Shoreham and Worthing are all particularly vulnerable. Over time, even small defects in pointing, render, flashings, or rainwater goods allow water to find its way inside.

Common entry points include cracked or hollow render, eroded mortar joints, defective window and door seals, blocked or leaking gutters and downpipes, and failed lead flashings around chimneys and abutments. The water path is not always obvious — moisture can track along lintels, through wall ties, or down concealed cavities before appearing as a damp patch some distance from the actual point of entry.

Left untreated, penetrating damp leads to plaster decay, timber rot, mould growth, and damage to decorations and furnishings. Identifying the precise source is key, because treating the symptoms without addressing the entry point guarantees the problem will return.

Our surveyor traces the moisture path from inside to outside, using moisture mapping, thermal imaging, and a methodical external inspection. We check every potential entry point — gutters, downpipes, flashings, pointing, render, window seals, and ground levels — to pinpoint exactly where and how water is getting in.

Repairs are tailored to the specific defect. This might involve repointing eroded mortar joints with an appropriate lime or cement mortar, patching or renewing cracked render, replacing failed flashings, resealing windows and doors, or overhauling rainwater goods. Where solid walls are persistently exposed to driving rain, we may recommend an external water-repellent treatment or a breathable render system to provide lasting protection.

Internally, we remove any damaged plaster, treat affected timbers if necessary, and replaster with appropriate materials. For solid-walled period properties we use lime-based plasters that allow the wall to breathe, avoiding the moisture traps that cement-based finishes can create. We guarantee our workmanship and ensure the underlying cause is resolved before any internal finishes are applied.