We live in a Victorian (1896) house with cavity walls. The damp proof course is not particularly evident and is apparently a bitumen layer (I have not been able to ascertain this despite trying).
There was a dodgy french drain that was filled by our builder that was cleared, filled up slightly and a channel put in (higher than the original floor of the french drain). Now there appears to be damp rising on the outside wall as evidenced by moss and green stuff appearing on the wall. What can be done to reinstate the integrity of the DPC? Should I go for injection of silicone?
On the other side of the house there is an intermittent render at the bottom of the wall (similar to that seen on terraced houses on the street side). This was disturbed when doors etc were shunted around. How can we make this continuous again? How deep does it need to go?