Most commonly builders lay the hardcore sand dpm and concrete slab finishing well below finished floor level.
How to lay a concrete floor in an extension.
We cover every stage from lifting the flags to troweling up the concrete including hardcore sand blin.
Once the house extension is built floor insulation and a screed layer of around 75mm with ufh pipes if required is then laid above the concrete slab.
Generally speaking there are two optio.
Tiles or floor finish of choice is then laid on the screed.
Concrete joists with lips on either side about halfway up are placed on the floor.
Beam and block floors.