Mould and how to avoid it

Remember, it is a condition of your tenancy to keep your property maintained, and this includes managing condensation. In some cases, we have had to charge students for damage caused by mould where it was avoidable.

If you feel you have taken all the reasonable steps to fight problems with mould but it is still winning, please let us know and we will assess if there is a maintenance issue.

How do properties get mouldy?

Damp

Mould grows in properties under damp conditions. Property damp can sometimes be cause by penetrating damp (rain water coming from outside), rising damp (groundwater seeping in) or plumbing leaks. By far the most common cause of damp, however, is condensation.

Condensation

Condensation is water that gathers on cool surfaces from moisture in the air. It occurs when the air in your property is warmer than the walls.

Student properties are particularly susceptible to condensation damp as they are densely occupied and often older constructions. A recent NUS survey reported 61% of students experience problems with condensation and mould in their housing.

Household condensation can make your property feel cold and reduce heating efficiency.

Worse, it provides the perfect habitat for MOULD to thrive. The problems with mould are:

  • It produces allergens. These can worsen asthma, give skin rashes, sneezing fits, and cause you to suffer cold-like symptoms.

  • It will make your clothes and property smell.

  • It damages surfaces, clothes, books, curtains, etc.

  • You might be charged for damage if you haven’t tried to manage it.

  • Once it grows, it’s very hard to get rid of completely.

Avoiding condensation

1 Ventilate well by opening windows as often as is possible/safe. If you can’t avoid drying clothes indoors, make sure you open all the windows you can. Ensure any trickle vents on windows are always open, and make use of windows that are designed to lock slightly open.

2 Heating evenly throughout the property will prevent cold spots. Keeping the heating off, then turning it up high when you need it does not give walls time to warm up to prevent condensation from warmed air; it’s better to keep the property slightly warm at all times (more on this below).

3 Minimise moist air by thinking about the activities you do. Drying clothes on radiators is the biggest contributor to condensation damp, cooking (especially without lids on pans), showers and even breathing all add up. Make sure doors are closed on areas containing damp air, such as bathrooms, to prevent it spreading through the property before it is ventilated away.

4 Allow airflow behind furniture. Behind wardrobes is a favourite place for mould to lurk. Moving furniture a little away from the walls will prevent this.

5 Wipe away condensation from windows in the morning, and any mould you see. Sometimes mould will appear no matter how well you ventilate and heat your property. You need to wipe this away as soon as possible to prevent it breeding or staining. Bleach will not get at the mould’s roots – use a proper mould cleaning fluid, or check online for other methods.

Heating and ventilating consistently stops condensation

Keeping your heating at low levels consistently will prevent walls getting so cold that moisture condenses on them.

Damp air comes from showers, drying clothes, cooking and even breathing. This damp air needs to be let out by opening windows.

The diagrams below demonstrate how to stop condensation damp occurring without paying for high bills. The arrows represent what happens to the moisture in the house.

What not to do: blast heat in short bursts

1) The house is unheated overnight. It's a cold night and by morning, both the air and walls inside are cold.

2) The household wakes up. They’re freezing, so the heating is turned up high and the boiler works hard, warming the air up. Air sucks up moisture as it warms, but walls are dense and need hours to warm up, so they remain cold. The windows are kept closed- it’s already freezing! Condensation is carried by the warmed up air and deposited on the cold walls as it drops to its dew point.

3) Everyone goes out, so the heating is turned off. The air cools down further losing it's capacity to contain moisture, which is dumped on the still cold walls. Mould growth becomes a problem.

What to do: heat moderately, consistently

1) Before bed, the thermostat is set low: 15°c. If the temperature inside drops to below that level, the heating will turn on maintaining that cool temperature.

2) In the morning, it’s a bit chilly, so the heating is turned up. Some windows are opened to let fresh air in and the moist air out. Condensation will deposit if the walls are colder than about 10-12°c, but as they were kept warm by the thermostat set to 15°c, condensation is minimal.

3) When everyone leaves, the heating is reset to 15°c to ensure the walls don’t get too cold, but use of heating is minimised. The worst of the damp air has been ventilated. Mould shouldn't be a big issue.

It is a matter of debate whether using short bursts of heating actually costs less than consistent heating. If you are worried about cost, we would suggest keeping heating consistently fairly low and just wearing a jumper. It’s likely cheaper to use heating consistently than to deal with the damage caused by mould.