I have had a new patio installed but the contractor left the DPM away from the wall in some areas and did not fix holes in other areas of DPM. Is there a way to patch up a DPM. Possibly Visqueen tape. I patched up an area in the wall/floor with ucan waterproof repair mortar where an old decomissioned pipe was exiting the building which was sodden and clearly letting moisture into the basement. I can't go down below what looks like a retrofit DPC because of a slab where I can see RSJ's. I am also thinking there is benefit in leaving the trench open but the fall of the quarry tiled area is pretty flat but goes slightly away from the area I want to direct the water to. Is there some way of screeding a grade away from the building that would adhere well to old quarry tiles? It is a Victorian building.
Fitting a French drain with gravel around it below the cellar floor level is the best solution. This will remove most of the ground water and allow the present damp proofing to work.