Condensation in the home

Condensation damage bathroom ceiling

One of the most common defects, found in almost every home in the country to a varying degree, is condensation.

Condensation is the term for droplets of water that bead on cold surfaces, particularly of windows and walls. It is clearly visible on cold car windscreens, and inside the home is most often seen on windows after running a bath or shower, or using cooker or tumble dryer. It occurs when humid air is cooled to its saturation limit, resulting in a transformation from gaseous to liquid form.

Winter is the worst time for this, when there are cool walls and windows, and freezing external temperatures, in stark contrast to the warm and moist environment within the building. In such circumstances, the process of condensation forming usually follows these steps:

  1. Cold air enters the building
  2. The air is warmed for the comfort of the occupants
  3. The warm air takes up moisture
  4. The warm, moist air comes into contact with cold surfaces, such as walls and windows, and is cooled below its ‘Dew Point’
  5. Condensation occurs as the excess moisture is released

The problem comes when condensation forms on elements of the internal structure, with moisture acting to speed deterioration and directly cause myriad issues – from fungal decay in floor timbers, to black spot mould on windows, paintwork, fabrics, walls and ceilings.

Modern homes are typically built to be extremely air tight, in accordance with Building Regulations. At the same time, they are also typically built with trickle and purge ventilation systems, which help to moderate the internal humidity and avoid condensation issues.

However, older properties and buildings with solid, uninsulated walls are particularly susceptible to issues with condensation. A certain level of condensation in such buildings is almost inevitable, but it is possible to manage this and avoid the defects that stem from it.

Serious condensation should be assessed by a specialist surveyor, but various tactics can be employed to help address both the moisture content in the air and the presence of cold surfaces.

  • Try to maintain a modest increase in background heat, as opposed to intermittent heating, as this will increase the ambient temperature of the building’s fabric.
  • Install purge ventilation in areas which produce the most airborne moisture, such as bathrooms and kitchens. This might take the form of a small mechanical extractor fan, some of which are fitted with a humidistat that will activate the fan based on real time humidity readings.
  • You might consider external, internal or cavity wall insulation to help improve the thermal dynamics of the building.
  • Consider investing in a dehumidifier. This device draws in warm air, then cools it to create condensation which is then captured in a reservoir for disposal.

If the problem persists, consider installing a positive pressure ventilation system (PPV). PPV systems gently pressurise the property which increases the flow of fresh, clean air throughout the home, removing humidity and stagnant air. This helps to remove condensation and reduce mould growth, as well as improving general air quality.

Chartered Surveyors meet condensation issues almost every week. If you’re concerned about mould, damp patches or other damp symptoms, speak to your local professional. They can guide you through the sensible steps to take and give advice tailored to your particular issue.