I am repointing a bungalow, circa 1960's. I have chased along each side of the dpc, (which looks like bitumen), but most of it has been pointed over solid and the remainder is in pretty bad shape - either very brittle with a raggedy edge, or already crumbled away. My question is what is the best course of action for repointing, considering most of the outside edge of the dpc is between 5 to 25mm back from the face of the bricks? I was planning on using a 3:1:1 or 4:1:1, but now wondering about using waterproofer in there also? It is going to be difficult to joint each side of the dpc as it is now.