Window mould

Andrew asks:
(updated on Tuesday, September 30th 2014)

We own a small two bedroom flat (circa 1980s). It is well maintained, has a heat pump and is fully insulated apart from the aluminium, single glazed windows. In winter this does result in some condensation on the windows which to our mind is easily taken care of by wiping windows in the morning and letting a bit of air through during the day. However our tenants are not doing this and the result is mould on the window ledges. They are demanding that we clean up the mould and upgrade the windows. Previous tenants have not had a problem so we are keen to understand the limits of our responsibility on this one as replacing all the windows with double glazing is not an option at this stage.

Our Experts Answer:

Under the Residential Tenancies Act 1986 (the Act), landlords have an obligation to ensure that the premises are maintained in a reasonable state of repair having regard to the age and character of the premises and the period during which the premises are likely to remain habitable. Furthermore a landlord must ensure that the premises complies with all the relevant health, safety and building regulations that apply to the premises. Where these obligations are met, the landlord may not be required to make additional upgrades to the property. Tenants have an obligation under the Act to ensure the premises are kept in a reasonably clean and tidy condition. It can sometimes be difficult to determine who is at fault when mould appears in a property. This is largely due to the fact that there are many reasons why mould and dampness may be present in a property. For example, tenants may cause excess moisture in the property by using un-flued gas heaters, drying clothes inside and not ventilating the property. Landlords may be responsible where the problem has arisen due to a maintenance issue which could include, for example, leaking pipes, or blocked guttering etc. Where it is unclear what is causing the dampness, or where it is not through any fault of either the landlord or tenant (e.g. due to the location of the property or if the property does not get much sunlight) then the responsibility becomes a lot less certain. In these situations, landlords and tenants should try and negotiate an outcome they are both happy with (e.g. whether a dehumidifier will remedy the problem and who will be responsible for cleaning costs). I suggest you discuss the issue with your tenants in the first instance and attempt to reach an agreement as to how the problem may be remedied. If an agreement cannot be reached, then either party may apply to the Tenancy Tribunal to have the matter resolved. To discuss your situation further, or for information about landlord and tenant responsibilities, you can visit the Ministry of Business, Innovation, and Employment’s website (, or call 0800 TENANCY (0800 836 262).

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