In article ,
T i m writes:
spalled yellow stock bricks) but then came to the (damaged / missing)
pointing over the slate dpc.

Now, am I supposed to add a waterproofer to the mortar mix for that
area or will plain motar be ok? (this is a single 4 1/2" brick wall,
rendered on the inside and the dpc is only about 1 brick course above
the surrounding hard standing).

Just make sure the slate edge is exposed and not bridged by mortar.
If the slate is missing at that point, put a piece of modern damp
course in instead.

--
Andrew Gabriel