Struggling with damp in your old stone or cob building? Learn effective strategies to control and prevent damp, including air flow, drainage, gutter maintenance, heating, chimney care, and breathable finishes.
Old cob and stone buildings can be warm, dry, and comfortable to live in when they are treated correctly. There are a number of strategies that may be employed to help control levels of damp within them.
Using Air Flow to Control Damp
If a building has good airflow, it's less likely to develop humidity and mould problems. Even if the building's exterior isn't perfect, good ventilation can help reduce indoor humidity.
Damp in buildings comes from two main sources:
- Everday activities such as cooking, bathing, and other activities release moisture into the air.
- Moisture in walls and floors can evaporate into the room, especially when the indoor temperature is higher than the outdoor temperature.
Old stone and cob buildings are made from materials that absorb and release moisture. This helps maintain a balance of moisture within the walls. However, if the building's weatherproofing fails, excess moisture can enter and evaporate into the living spaces.
To prevent this, maintain a steady flow of fresh air. You can achieve this by:
- Using trickle vents.
- Installing a positive pressure ventilation system.
- Opening windows slightly.
Airflow is a simple and cost-effective way to manage damp. However, to fully address the issue, you may need to consider other factors.
Improving airflow is often the simplest and most affordable way to reduce damp. However, it’s important to remember that it’s just one part of the solution.
To truly address damp issues in an old building, a thorough survey by a qualified professional is essential. This will help identify the underlying causes of the problem, such as faulty drainage or poor insulation.
It's important to avoid quick-fix solutions, as they may not address the root cause of the damp. By taking a comprehensive approach, you can save money and create a healthier living environment.
A professional building survey can help identify the root causes of damp and recommend appropriate solutions. It's important to understand that damp often results from multiple factors. Ignoring this and installing modern ‘damp-proofing’ measures often proves to be both costly and ineffective.
Using Drainage to Control Damp
A damp-proof course is a barrier designed to stop water from rising up the walls of a building. However, most old stone and cob buildings don't have this feature.
To protect these buildings from water damage, it's essential to have good drainage around the base. This means directing rainwater and runoff away from the walls.
One common problem is poorly connected downpipes. These should drain into a gully or drain grid, not directly onto the ground. This helps prevent water damage to the walls and finishes of the property.
French drains are sometimes used to improve drainage. However, they must be installed correctly to avoid causing water to pool at the base of the drainage trench or damaging the building's foundations.
They should be specified with caution, as poorly installed or located French drains can undermine the shallow foundations or create conditions for water to puddle at the base of the wall.
If French drains are to be installed, they should be at least 400mm from the base of the wall, and their suitability as a remedial measure should be assessed by an experienced surveyor with no vested interest in carrying out the work.
Maintaining Gutters and Downpipes to Control Damp
Gutters are a crucial part of protecting your building from the weather. Unfortunately, they're often neglected, which can lead to serious problems occurring such as structural damage, mould growth, and increased humidity.
When gutters and downpipes overflow, they can direct large amounts of water onto the walls of your building. This can cause water damage, leading to issues like rotting timbers and crumbling mortar.
To prevent these problems, it's essential to maintain your gutters and downpipes. Regularly clean them to remove debris and ensure they're securely connected. Consider installing additional downpipes to handle heavy rainfall.
Even small leaks can cause significant damage over time. Look out for signs of water damage, such as dark stains on walls or vegetation growth. A professional inspection can help identify potential issues and recommend solutions.
Investing in a well-designed guttering system can save you money in the long run by preventing costly repairs.
Maintaining Gutters and Downpipes to Control Damp
Old stone and cob buildings can feel much drier when heated consistently at a low temperature. This is because their thick walls take time to warm up.
When you turn on the heating, the air warms quickly, but the walls remain cool. This can cause moisture to evaporate from the walls and condense on cold surfaces, leading to mould growth.
To prevent this, it's best to keep the heating on at a low, consistent temperature. This allows the walls to warm up gradually, greatly reducing the risk of condensation.
Maintaining Chimneys to Control Damp
Leaky chimneys are a major cause of water damage in old stone and cob buildings, often leading to issues like mould and structural decay.
Many older chimneys lack proper flashing and drainage, making them vulnerable to water ingress. This can damage the chimney itself, as well as the surrounding walls.
When water seeps into a chimney, it can travel down the flue and damage the mortar and stonework. This is particularly problematic in areas like Cornwall, where many old buildings have clay mortar that can erode easily.
While it may be tempting to patch up a leaky chimney, this is often a temporary solution. It's best to have a professional assess the damage and recommend appropriate repairs. Drone inspections can provide a detailed view of the chimney's condition, helping to identify the extent of the problem.
Breathable Finishes to Control Damp
While lime isn't a magic solution for damp in old buildings, it's a valuable tool for maintaining their historic character and functionality. Lime-based plasters and renders allow walls to breathe, releasing excess moisture into the atmosphere. They can also accommodate minor movement in the building structure and protect the underlying masonry.
Cement-based finishes, on the other hand, can trap moisture within the walls. This can lead to damp, mould, and other problems. While cement is suitable for modern buildings, it can be detrimental to older structures that rely on the natural movement and breathability of their materials.
By using lime-based finishes and other appropriate techniques, you can help ensure the long-term health and preservation of your old building.
Here at Muddy Mortars, we have extensive experience working with lime and can provide expert advice on how to best address damp and other issues in your historic property.
