Dampening the Myth: Debunking the Truth About Rising Damp

Image showing damage caused by a retrofitted injected damp-proof course in a sandstone building.

The notion of “rising damp” as a distinct phenomenon has been widely challenged in recent years, with many experts arguing that it is a myth. While it is true that moisture can be drawn up through porous materials like masonry and brick, this has never been found to rise above 100mm and certainly not to 1.5 meters as most damp companies state as the height that ‘rising damp’ reaches in walls. In reality, moisture problems are typically caused by a combination of factors, including poor ventilation, lack of maintenance, leaks, and construction defects.

The most common source of moisture in buildings is water infiltration from the exterior. This can occur in many ways, including:

• Rainwater penetration: Rainwater can enter a building through gaps in the roof, walls, windows, and doors. This can cause water damage to the building materials and lead to mould growth.

• Groundwater infiltration: When the soil around a building is built up against the external walls and is above the internal floor level, this can become saturated with water; it can then bridge the masonry units and cause dampness internally.

• Plumbing leaks: Leaking pipes or fixtures can cause moisture to accumulate within walls, floors, or ceilings. This can lead to mould growth and deterioration of the building materials.

• Condensation: Moisture can form on cold surfaces when warm, humid air comes into contact with them. This can occur in poorly ventilated areas, such as bathrooms and kitchens, as well as in attics and basements.

• Human activities: Everyday activities like cooking, showering, and even breathing can release moisture into the air, which can then condense on cold surfaces.
  

When it comes to traditional buildings which are often referred to as buildings built pre-1919 and more recently described as solid walls (i.e. not cavity walls) or solid timber frame construction using moisture-open materials, traditional construction differs significantly from modern construction, having different materials, construction methods and designs. Traditional buildings make up about 25% of the UK’s total building stock. The reasons for dampness become more complex in traditional buildings, and these buildings are subjected to damp remedial work that, in many cases, hides the issue rather than solves the problem. The issues listed above are often the source of moisture in traditional buildings though there is one factor that is often never discussed in a 'Rot and Damp' survey and is always part of a contractor's remedial works. The missing link is modern moisture-closed materials.

• Moisture closed materials: Many modern materials, such as cement, gypsum plaster, plastic, and non-porous paints, are non-breathable. This means that they do not allow moisture to escape from the building fabric, which can lead to condensation and dampness.

• Lack of ventilation: Traditional buildings were often designed with natural ventilation in mind, allowing for air to circulate and moisture to escape. Modern materials such as double glazing, plastic window frames, and air-tight insulation, along with bricked-up fireplaces and blocked air vents, can reduce ventilation and exacerbate dampness issues.

• Inappropriate repairs: When traditional buildings are repaired or renovated, it is important to use materials that are sympathetic to the original fabric. However, inappropriate repairs using modern materials can trap moisture and lead to dampness.

• Changes in building use: Traditional buildings were often designed for a specific use, such as a home or a small business. Modern use of these buildings can lead to changes in ventilation and moisture levels, which can cause dampness issues. When most traditional buildings were built, our habits were completely different; we wouldn't have showers/ baths every day, we didn't boil the kettle as much, and we didn't have gas cookers. All of these activities create excessive amounts of moisture and can cause serious issues in a building if they are not understood and dealt with. We also used open fires to heat each room which promoted ventilation and drying of the wall.

• Chemical treatments: Modern chemical treatments used to treat dampness can sometimes cause more harm than good. For example, some modern waterproofing treatments can trap moisture in the building fabric, leading to dampness issues.

While “rising damp” may be a term commonly used to describe moisture problems in buildings, it is an oversimplification of a complex issue; a combination of factors, such as poor ventilation and high groundwater levels, usually causes it. Unqualified or inexperienced contractors often misdiagnose the cause of dampness as ‘rising damp’. Always remember that a damp-proofing company has a vested interest in selling a damp-proofing product; their free survey is a quote.

If you have moisture issues in your building, please don’t hesitate to contact us at 01412379491 or drop us an email info@hisurv.co.uk. We look forward to helping you.