Dear Sir or Madam

The tenant would be responsible. When you rent a property you are renting it as it is. Any apparent flaws, i.e. damp patches, are expressly accepted by you on letting the property and the landlord cannot be held liable for them. In other words, you rent it as it stands with apparent flaws and all.

Properties below ground level or facing north are always prone to attract dampness in my experience specially in developments with lush gardens that need to be watered regularly. Which is yet another reason why tenants and would-be-buyers choose, if possible, south facing properties flooded with sunlight and warmth.

A different matter would be if you had rented this property and after a few months for example of heavy rainfall the roof water seeped through or huge growth moulds appeared in which case the landlord would be responsible forh to mending them.

Yours sincerely,
Raymundo LarraĆ*n Nesbitt