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Private liability
Household contents

What to do when you find mould in your apartment

Mould can have many different causes, including water leaks, excessively high levels of humidity, and building defects. Finding mould damage in your apartment raises a number of questions.

7 May 2019, author: Manuela Locher, photo: Helvetia

Two people sit in an apartment and deal with documents.
Mould in your apartment is not only annoying and dangerous – it often also leads to a dispute between the landlord and the tenant.

Who has to foot the bill when mould is discovered in an apartment?

Mould in a rental property not only poses a health hazard for the residents – the cost of eradicating it can spoil your enjoyment of living there. Merely obtaining an expert opinion on the contamination can cost thousands of francs. As far as paying for the eradication of mould is concerned, the polluter-pays principle applies: whoever caused the damage ultimately has to foot the bill for it.

But, in practice, it is often impossible to determine the true culprit with any certainty. Determining who is at fault is often not possible without commissioning costly expert opinions, which is why many such cases lead to disputes between tenants and their landlords that quite often end up in court. Once the legal situation has been clarified, there are various options.

Mould due to building defects – landlord responsible

If the mould is attributable to a building defect, the landlord is liable for the damage. As the tenant, you are entitled to apply for a rental reduction for the period during which you are unable to use your apartment in line with the conditions of your rental agreement. The amount of the reduction corresponds to the extent to which you are unable to use your apartment.

Mould from incorrect ventilation – tenant responsible

If it can be clearly proven that you, the tenant, caused the mould by failing to ventilate the apartment properly, you are responsible for repairing the damage. But eradicating mould is often very costly. This is where the right insurance cover can save you money. 

The right insurance to cover mould

Private liability insurance:

If your landlord is responsible for the mould, he is liable for the damage. Apart from the trouble and inconvenience involved, you will incur no additional costs. If it can be clearly proven, however, that you are responsible, damage to the rental property will be covered, at most, by your liability insurance. However, liability insurance does not cover damage to your own personal belongings.

Household contents insurance: 

As a rule, household contents insurance does not cover damage due to mould. But, if the mould is the result of water damage that is covered under the household contents insurance policy, any affected furnishings will be covered. If your landlord is responsible for mould damage to your household contents, his liability insurance will cover it.

Tips and tricks for preventing mould

There are a few rules of thumb you should observe to stop mould from forming and spreading in your apartment in the first place:

1.    Ventilate properly

Proper ventilation is the key to preventing mould, which is why experts advise you to air your apartment once a day:

  • Open the windows wide for three to five minutes every day 
  • The colder it is outside, the shorter the time needed for airing 
  • If you can get flow-through ventilation occasionally, all the better
  • Air the rooms even if it is foggy or raining outside
  • Don’t forget to air rooms located in the cellar

2.    Heat properly

The temperature inside the apartment is also a key factor for the formation of mould because cold rooms are more likely to be affected by mould than heated ones. Never turn the heating off altogether and make sure the temperature never drops below the recommended minimum of around 16° Celsius.

3.    Keep a check on humidity

Water vapour forms easily in kitchens and bathrooms. Where there is a lot of steam, open the windows so as to ensure it cannot settle on the walls.

Should I report mould to my landlord?

Preventing mould is better than trying to eradicate it. But what should you do if you detect signs of mould in your apartment?

In such cases it is advisable to inform your landlord immediately. That way you can not only avoid possible damage to your health, but also prevent the spread of mould to other areas and objects. Photos documenting the extent of the mould can be very useful in cases like this.