I am interested in a house which needs renovating and has been derelict for some time (squatters). There has been a blockage in the drains at the rear of the house. This has caused water to seep in and flood the interior utility floor this causing the walls to grow mould to a point where it has turned black and smells like someone died.

Can these walls be saved? I'm not aware of the damaging effects that mould and flooding can have on a property. Once I have unblocked the drain and removed the cause can the walls be dried out and treated?

Any help would be appreciated as I'm totally in the dark on this subject.

Also there is an external vertical crack (not stepped or very wide) running from the base of the wall to the top where the kitchen would start at the back (not a new extension). There are no signs of it showing inside but is this reason enough to run as fast as I can away from the house?