We have recently discovered that the neighbours paved path is a few cm above our DPC. There is a gully between their path and our wall, filled with gravel - presumably to act as a French drain. However, the top of the gravel is around 8cm above our DPC rather than the often-quoted 150mm below it. I have uploaded a photo showing this.
Our neighbour is lovely and it was the previous owners who must have installed the path, so we're keen to explore the simplest and most cost effective solution. I had wondered whether I could install chemical DPC rods on the next level up, but then I thought that this may be too high and the damp would continue to come through the wall below it.
So today I drilled an exploratory hole through the mortar in the brick course above the existing DPC and found that the DPC is around 7cm above the internal floor. This was never a problem until the path was laid bridging the DPC, but I don't think creating another higher DPC would achieve anything as damp isn't rising far up the wall anyway and it's mostly the bottom and skirting that are the most damp.
I would very much welcome any suggestions that would avoid lowering the path or perhaps even digging a much deeper gully - which the neighbour isn't keen on as she feels it might be a hazard, as well as being a big job. I've read that one possible solution might be to dig down to a couple of courses below the DPC, clear the soil from the wall and then install a membrane against the wall (perhaps flashing or a roll of DPC standing up as a baffle) and then backfill with gravel. Does this sound like a good idea or a terrible one?
Obviously, any better suggestions would be greatly appreciated!
Many thanks