The floor you are standing on in Rugby is usually one of two things, and they are not interchangeable. The terraces near the town centre have suspended timber ground floors over a ventilated void, so the questions are the condition of the joists, the airflow under them, and whether the existing boards are worth keeping.
The post-war housing out towards Bilton, Hillmorton and Overslade is generally solid concrete, where the questions are level and moisture instead. A floor that is 20mm out across a room is common on both, and it is the single thing that decides whether a new covering sits right.
The two also fail differently. A suspended floor that has lost its airflow goes soft at the edges and around the hearth; a solid floor that has lost its damp proof membrane shows at the perimeter and under anything impermeable laid over it. Neither is fixed by the covering that goes on top, so we establish which one we are dealing with first.
We survey and level before we lay. The build-ups we use are on our flooring page.