If mould, damp or vermin appears in a rental property during the tenancy, the tenant should notify the property manager/owner as soon as they are aware of the issue.
If the issue is caused by problems with the structure of the property, the property manager/owner is responsible for fixing it and making any necessary repairs. Examples could include mould caused by a leaking roof or a termite infestation in the walls. The property manager/owner is also responsible for fixing any issues that are caused by reasonable use of the property. Examples would include a leaking shower which cannot be turned off or a stove top that does not work.
If the issue is caused by the actions of the tenant, the tenant is responsible for any necessary repairs. Examples could include mould caused by the tenant allowing steam to build up in a bathroom and not properly ventilating or cleaning the area, or a vermin problem which may have been caused because the actions of the tenant attracted the animals to the property.