Have just moved into a house that s 150 years old, the hallway was sloping (not subsidence) on taking up the tiles the whole floor practically came away with the tiles, Im now left with a hallway that s down to the ground literally (earth) which is about 2" lower than the level of the skirting board, I was going to attempt to concrete this myself but am unsure if I should use dust or sand to bring the floor up first. Any help would be appreciated.