We have a mid terraced Victorian (1860s) house in North London. The basement is a separate flat and we let it out. It is currently between tenants, after a four year tenancy, so we are getting some work done.
There are two issues:
1) There are a couple of damp of damp patches in the hall. A couple of years ago the moisture in the flat was quite bad and DH had a "damp specialist" put in a damp proof course (I assume this was what it was - DH said that someone injected something into the wall). We also had a dehumidifier running for a while and the problem disappeared. The damp patches have now returned. One is at the base of the hall next to the bathroom. The other is about a metre above the floor, in the same spot as previously.
2) There is a cupboard under the external stairs to the upper maisonette. This cupboard is a real disgrace - the render on the walls is buckling and it is black with mould. Our builder has recommended stripping the walls, and re-rendering with added waterproofer. I'm concerned that this would just trap the moisture in the brick walls leading to the same problem five years down the line.
I should be grateful for any thoughts you have on this, and if you can recommend any builders who are knowledgeable about period properties it would be great. Our builder does a reasonable job but I'm not sure how good he is about diagnosing issues like this.