On 18/07/2019 21:38, Tim Lamb wrote:
I am planning a single pitch roof fitted between two existing cavity
walls (house/old garage) and am contemplating fixing to the walls rather
than using vertical supports from foundation pads.
The outer skin brick is sound but uses wirecut extruded brick with lots
of internal holes. Any drilled fixing hole has a 50% chance of finding a
cavity!

Any suggestions. Concrete screws with the holes pre-filled with resin? or?

If you have a loose brick you might be able to see where the frogs or
holes are and avoid drilling bricks at those locations on each brick.

You could use anchor bolts long enough to go right through the bricks,
and anchor on the far side. But if you do that drill carefully after
your bit has passed through the hole so you don't blow the far side of
the brick.

Since the load will not be 'pull-out' I would have thought 10mm holes,
blue plugs, and No 10 or 12 woodscrews, fixing to the masonry between
the hole in the brick and the surface, would be fine.

Much depends on the hardness of the bricks.

Bill