Roger addresses a damp problem question posed by Elizabeth concerning her kitchen and adjoining walls in an old house.
Elizabeth explains that after a damp proofing treatment was done on a problematic kitchen wall and chimney repairs were completed, the damp patches and salt deposits on the walls remain, causing concern.
Potential causes, structural features, the type of walls (solid or cavity), and past water ingress sources, like a washing machine leak or roof gutter issues. He highlights the importance of understanding precisely what damp proofing work was done, emphasising that vague or incomplete treatments often lead to recurring problems.
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Key Insights
🧱 Understanding Wall Construction Is Essential: Roger highlights the difference between cavity and solid walls, which affects how damp manifests and how it should be treated. Cavity walls may suffer from water ingress through the cavity, requiring different solutions than solid walls, where historical damp might be present. Knowing the wall type helps tailor the repair correctly and avoid ineffective treatments.
🔬 Salt Deposits Are a Key Indicator of Moisture Issues: The presence of hygroscopic salts that attract moisture can cause paint flaking and plaster deterioration. These salts act like sponges, continually bringing moisture to the surface, which means that simply repainting or superficial repairs won’t solve the underlying problem. Proper removal and use of breathable plaster materials are necessary to halt this cycle.
🏚️ Historical Water Ingress Can Create Long-Term Damp: The chimney’s lack of a pot or cap for an unknown duration allowed rainwater to penetrate deep into the structure. This kind of chronic water ingress leads to damp problems that are slow to resolve, sometimes taking up to a year or more. Quick fixes and short drying time expectations are often unrealistic in such cases, especially in older buildings.
📑 Clear Documentation and Scope of Work Are Crucial: Elizabeth’s vague description of “doing what was needed” reflects a common issue—homeowners often don’t have or don’t request detailed quotes or work descriptions. Without clear documentation, it’s difficult to assess the effectiveness of the damp proofing or hold contractors accountable. Roger advises always obtaining and reviewing detailed work scopes and materials used.
💨 Indoor Humidity Control Is a Vital Part of Managing Damp: Even after external repairs, internal moisture from cooking, washing, and poor ventilation can contribute to damp problems. Roger stresses the importance of extractor fans vented externally rather than recirculating filters and using humidity sensors to monitor moisture levels. Managing indoor air quality can mitigate condensation-related damp and salt activation.
🛠️ Proper Materials and Techniques Matter: Roger advocates using breathable materials like lime or cork plaster for replastering damp walls. These materials allow moisture to escape without damaging finishes, unlike sand and cement renders that trap moisture and exacerbate salt damage. This highlights the importance of specialised knowledge in damp remediation rather than generic plastering.
⏳ Patience and Realistic Expectations Are Needed in Damp Treatment: Damp problems, especially in old buildings, rarely resolve quickly. Roger advises patience and monitoring over months rather than weeks. This realistic approach helps homeowners avoid unnecessary repeated repairs and understand the slow nature of drying and salt migration processes.
#damp #homeimprovement #dampproofing
