The picture shows the extent of the steel work now that the scaffolding has been removed. Toward the base of the new steel column, you can just make out the thermal break. The new insulated floor level is approximately 30mm above this break, and so the existing needs to come out.
Concerned that a breaker drill will cause too much vibration (and noise), it is decided that a concrete saw would be best. This will cut the slab into chunks of manageable size for the digger to ‘scoop out’.
The photo above shows the saw in use. It takes best part of the day to cut the slab, but it is a success and the slab is removed. Beneath the slab is solid, rocky, undisturbed ground. The digger scoops out around 650mm of earth beneath the slab. This reveals the base of the back and side walls, ready for the under pinning. See next update