What to fill the cavity with

[plugy]

We've just replaced a small extension back of our house. The brickwork comes up around 2.6ft before the inside floor level, obviously needing steps outside.
Should you still fill the cavity just below DPC?.
Should the inside brickwork be lower to allow us to bring up the underfloor insulation in the cavity and under the proposed screed floor?

 

[jks7492]

Yes fill the cavity with concrete to 225mm below DPC.
Especially if you have a ground-bearing slab as your external wall will also now be acting as a retaining wall.