JK wrote:

This doesn't sound like a diy job. Not if you mean the application
of one of those terrifying massive grinders that pavement operatives
use in busy shopping centres to cut curbstones! How wide does such a
trench need to be anyway?

More of a spring job than a winter one but not too arduous. You'd be
surprised how thin the concrete turns out to be, maybe only 1" over rubble,
especially if it is an old house. Like Niel says a 6" from the wall is good,
the depth is dependant on your own circumstances. An angle grinder won't go
through the whole thickness but will provide a score line which will
encourage the concrete to crack along it. USe a variety of hammers, drills,
chisels, picks, levers etc to create the channel.

New houses with paving around them often have a deep fill of pea shingle or
gravel around the walls.

--
Toby.

'One day son, all this will be finished'