The sitting room floor was a tricky customer – if it were any less of a level playing field, it’d be the US healthcare system. Levelling this involved digging up old concrete where possible, filling with insulation and damp proof membrane, then concreting over. The levelling phase mostly happened at the end of June but for some reason (probably complete denial) I neglected to write about the carnage at the time:
We went with laminate flooring over extruded polystyrene underlay: