Condensation

Condensation occurs when warm air meets with cold surfaces and/or when there is too much humidity in your home. The amount of water that the air will hold in vapour form depends on temperature. As the temperature reduces, the air will hold less moisture and any excess will begin to condense on the nearest cold surface.

Normal everyday activities such as cooking, showering, and drying clothes on maidens or on radiators increase the amount of moisture in the air inside the property. When this moisture-laden warm air comes into contact with a cold surface such as an outside wall or a window pane, it cools down quickly and releases the water, which turns into liquid droplets.

In the cold winter months, the humidity inside properties is higher than in the warm summer months. This is because we tend to have the heating turned up high and the windows closed. Hence, condensation is more likely to occur during this season.

If condensation isn’t dealt with promptly, it can go on to provide the right conditions for black spot mould to start growing on walls, ceilings, and around windows. Black spot mould is unsightly and can lead to health issues for occupiers including sinus problems, skin rashes, and bronchitis.

All properties have potential for condensation to occur but flats and bungalows are especially at risk because they are on one level and a lot of water vapour is generated on that one level.

What are the signs of condensation?

• One of the most common signs of condensation is black mould which can occur on any walls of the property. This compared to rising damp where if mould is present it will only occur on the ground floor of the property.

• Water will collect on windows is a common symptom of condensation in homes.

• Plaster will start to deteriorate if the condensation problem is not treated quickly. The walls will also appear wet.

“Raining” in the loft

This may be less familiar but is worthy of mention. With houses being fitted with 300mm of loft insulation, the loft areas are becoming very cold and any cold surfaces will reach dew point very easily. Hence we can see water droplets on the underfelt.

There is no mould, can I tell condensation is present by using my damp meter?

The damp meter will give a reasonably good indication. You are likely to find high readings to the plaster close to the skirting boards which fall very quickly as you go up the wall. The skirtings are likely to have low readings.

There may or may not be a salt band. If the problem is just condensation, then there will be no salt band. If there has been a previous rising damp problem and chemical treatment and replastering, there may be a salt band.

What remedies are there?

These fall into three categories depending on the primary cause. More than one cause may apply.

1. If the house is too cold:

• The heating system may be old and inefficient

• The owner may not be using the heating

• Insulation may be poor.

The remedies here are to improve the heating and insulation where reasonably possible.

2. If ventilation is poor (or if there is too much):

• Windows and doors may be draughty (too much ventilation)

• Window vents may not be used (too little ventilation)

• Extractor fans may be missing or not used

• Airbricks may be blocked up.

The remedies here are to reduce draughts from windows and doors, ensure that trickle vents are fitted, and to fit and use extractor fans in kitchens and bathrooms.

3. If the house is too wet

• Owners may be drying clothes on maidens

• There may be flueless gas heaters venting combustion gases into rooms (old style gas fires and portable gas heaters)

• Tumble dryers may not be vented

• Owners may be cooking without opening windows

Some assistance may be gained from running dehumidifiers but the main remedy is to reduce and control moisture.