Subscriber OnlyResidential

The apartment I’m renting is mouldy and damp. What can I do?

Property Clinic: The issue of mould in apartments in Ireland is commonplace

I have been a tenant in my apartment for two years. Last year there was a leak from the apartment above which left the walls in my bedroom and bathroom damp. The bathroom walls were painted over but the paint has cracked again as the damp issue wasn’t resolved. Black mould has appeared in the bedroom, which I have removed a number of times. However, the room smells damp in the winter months and I have found mould on a number of items in my wardrobe. I brought it up with my estate agent in January, sending photos of my clothing with mould and the cracked paint on the walls. I was given a dehumidifier for a week to resolve the issue. It’s now coming into winter again and the issue is getting worse. I’ve purchased my own dehumidifier but it’s not going to resolve the underlying issue. How do I get this resolved?

What you have described in your query may very well be two separate issues and it is important to establish the position with regard to both issues, writes Aisling Keenan. The first issue concerns the water leak. Normally when a leak occurs the remedy is to find the leak and fix it. Firstly, the question that needs to be answered here is, was the leak found and fixed? If it was found, then what was the cause? If the leak was fixed, then how was it fixed and are there details available on the scope of works for fixing the leak?

If there is a report that describes what the cause of the leak was, and states how it was fixed and confirms that the leak was fixed, then what you are experiencing with damp and mould in the apartment is a separate matter to a water leak and must be addressed differently than a water leak would be addressed.

The issue of mould in apartments in Ireland is commonplace and has two main causes. (a) The construction type of the building and (b) the living conditions inside the apartment. Damp and mould inside an apartment are caused by an incorrect balance between temperature and ventilation. The temperature inside the apartment will very often be determined by how well insulated the apartment is. For example, the vast majority of apartments that were built up to five years ago will have windows and walls that do not have a high U-value. The U-value is the rate of heat transfer or heat loss, the lower the U-value, the less heat loss.


When the temperature inside the apartment is higher inside than the temperature outside the apartment, what happens when the apartment is occupied is that moisture is created inside the apartment, which will condense. Air contains invisible water vapour. The amount it can hold depends on its temperature. Warm air holds more water vapour than cold air. When warm moist air meets a cold surface, it will cool and become saturated. If it cools further, some water vapour will condense on the cold surface such as water droplets inside a window. This is what causes mould and damp.

Adequate ventilation will offset this problem and so it is important to keep your apartment well-ventilated to reduce damp or mould. The problem with this in Ireland is that with cold weather it is not a preferable solution to have the windows open in the apartment. A heat recovery ventilation unit can be installed which will ventilate the apartment without circulating cold air; it simply recovers the heat in the apartment while ventilating.

The Society of Chartered Surveyors of Ireland have further information on this topic on its website at

Finally, one thing to consider is that if the water leak was not resolved properly, the ingress of water could be a contributory factor to the mould and so the problem will have to be addressed with a holistic approach taking all factors into consideration.

Aisling Keenan is a property managing agent and consultant and an associate member of the Society of Chartered Surveyors Ireland

Do you have a query? Email

This column is a readers’ service. The content of the Property Clinic is provided for general information only. It is not intended as advice on which readers should rely. Professional or specialist advice should be obtained before persons take or refrain from any action on the basis of the content. The Irish Times and it contributors will not be liable for any loss or damage arising from reliance on any content