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Condensation and Mould


Condensation occurs mainly in the winter, when a buildings structure is cold and when properties are not properly ventilated; windows are not left open and moist air cannot escape. Condensation occurs when warm, moist air meets a cold surface. The risk of condensation depends on how moist the air and how cold the surfaces are within a property. Both of these factors depend, to some extent, on how a building is used.

While condensation can have horrid consequences if left untreated, this build-up of moisture is usually the easiest damp problem to fix, especially if dealt with at the first signs. The solution to this problem can be quick and easy to fix if both landlords and tenants work together to cover all bases before the problem arises. In fact, it can almost always be prevented from occurring all together.

Bathrooms and kitchens are particularly common with condensation as a result of a steamy atmosphere; it is also common in unheated rooms, mainly bedrooms. It can be found in cupboards or corners of rooms where ventilation and movement of air are restricted. If you find your property is suffering from condensation, be sure to check out of sight areas; behind furniture, in wardrobes and cupboard spaces. If left it will cause damage to your belongings.

The following steps should prevent condensation;
1. Provide ventilation to rooms
2. Limit the spread of moist air to additional areas
3. Keep heating to a constant low setting during the colder months

Good ventilation in a property, especially in kitchens and bathrooms is essential. If you can install an extractor fan to both rooms and make sure both are used when cooking, washing and drying clothes, bathing and showering, this should help to minimise condensation. The extractor fans should be left on until all misting has cleared and it is advisable to shut doors long enough to dry off the rooms. If there is no extractor fan, the windows should be opened during these times and all doors kept closed as much as possible. This will ensure the moist air does not spread to other rooms where it may cause trouble.

It is not only kitchens and bathrooms that need ventilation. Windows or vents should be opened for a reasonable time each day. Too much ventilation in cold weather can be uncomfortable and can waste heat, however, all that is needed is a very slightly opened window or vent for it to sufficiently work.

Partially heating rooms continually through the colder months can prevent condensation. Providing heat should be a priority and heating should be kept on a constant low setting, even if the property is vacant. Houses and flats left unoccupied and unheated during the day get very cold. The heat provided has to keep the room surfaces reasonably warm and it takes a long time to warm a cold building. It is much better to have a small amount of heat over a long period of time rather than to provide a lot of heat for just a short time.

Any sign of mould growth is an indication of the presence of moisture and if caused by condensation gives a warning that heating, structural insulation or ventilation may require improvement. Any signs of mould growth should be investigated as soon as possible so that an investigation into the cause of the issue can be carried out.

Mould is an unsightly and occasionally health-concerning issue that affects both tenants and landlords up and down the country. Not only does it make a rental property unattractive to current or prospective tenants, but it can also be costly to fix. As a result, it is important for landlords to not only understand what their responsibilities are when it comes to damp and mould but to also ensure that all parties are doing everything they can to prevent it from occurring in the first place.


Mould is a fungus that can have a negative effect on both a persons health and the property value and can grow on almost any surface in a property where there is an excess of moisture. This moisture can be the result of a number of factors; therefore, it is imperative for landlords to be as knowledgeable on the subject as possible.

Rising damp is the result of water rising from below a building. The water enters a property through porous materials such as bricks and mortar and is often because the property damp course (a layer of waterproof material in the building’s wall near the floor) has failed.

Penetrating damp is another common cause of mould. This occurs when a building has structural issues, such as leaking gutters, which allows water to seep through.

Quite possibly one of the biggest causes of damp and mould is condensation, a fact that many people, including both tenant and landlord are not aware of. When a building is not properly ventilated, excess moisture can form in the air. This forms water droplets inside a property and can lead to condensation and surface mould.

There is a lot of confusion around the topic of who is responsible for damp and mould in a rental property; is it the duty of the tenant or the landlord to treat the issue? A lot of the uncertainty comes from the fact that both parties are not always clear on the multiple causes of damp and without liaising with an expert to recognise the moulds origin, it is a tricky problem to fix.

The Fitness for Human Habitation Act, which was introduced in March 2019, now holds landlords accountable if a rental property does not meet certain standards. This means that it is now a landlords responsibility to fix problems such as damp caused by design defects, and if they do not, the tenant will have the right to pursue legal action. This does not mean that landlords are responsible for tenant neglect and it is therefore important for tenants to raise any concerns to their landlord/managing agent as soon as the issue arises.

The best approach to a mould free property is prevention and there are a few basic things landlords can do in an attempt to control moisture in a building:
1. Identify any possible problems and fix them as quickly as possible
2. Fit extractor fans to kitchens and bathrooms
3. Decorate properties with mould-resistant products such as anti-mildew paint
4. Regularly clean and repair gutters

Tenants can also play their part in reducing the risk of condensation and mould:
1. Drying wet areas as soon as possible
2. Opening windows frequently to allow ventilation, especially when cooking, having a shower/bath, washing up and washing and drying clothes
3. Improving airflow in the property; opening doors between rooms and positioning furniture slightly away from walls
4. Cleaning damp rooms such as bathrooms with mould-killing products

If mould is already present and appears to be on a small scale, it can be cleaned with detergent and water or an anti-mould spray. The person doing the cleaning should wear gloves, protective goggles and a dust mask. A property should be well ventilated after cleaning to ensure the mould does not return.

If the mould is a larger issue or if it continues to return, then the problem is best passed onto a professional.