Hello
I am a qualified Home inspector I carry out surveys on properties and will gladly help you find out where the damp is coming from, if you would like to send some photos of the affected areas inside an out and a description of where it is and the height up the wall of the damp and so on.
The Damp problem is usually something that is easily discovered and can be rectified without any large costs being involved.
So if your interested I will look for free
Kind Regards Adam
www.inspekto.co.uk