The tolerance we are working to
British practice is a maximum deviation of 3mm under a 2-metre straightedge. That sounds strict until you lay a thin LVT plank over a 6mm dip and watch it flex, click and eventually crack at the joint. Wood is more forgiving than vinyl, and a floating floor more forgiving than a bonded one, but the tolerance exists because floors fail without it.
Latex levelling compound
A self-smoothing cementitious compound poured over a primed screed or concrete slab. Typical cost is £8–£15/m² depending on depth and whether the substrate needs priming or a moisture barrier first. It cures enough to walk on in a few hours and to lay over in 24, which is why it rarely adds a full day to a programme.
- Shallow skim to correct minor undulation: lower end of the range
- Deep fill over a badly worn screed: upper end, sometimes two pours
- Always primed first; unprimed latex bonds poorly and lifts later
Ply overlay on timber subfloors
Over floorboards or chipboard, the usual solution is 6mm or 9mm ply screwed at close centres — typically £12–£20/m² supplied and fitted. It flattens the surface, stops individual board movement telegraphing through, and gives a nailable deck for solid wood. It also raises floor height, so doors need trimming and thresholds need thinking about.
Screed repair and damp-proofing
Crumbling or dusting screed needs consolidating before anything else happens; high moisture readings need a liquid damp-proof membrane, usually two coats. Both are priced per m² and both are non-negotiable when the survey shows them. Laying a floor over a damp slab is how you end up relaying it eighteen months later.
What happens if you skip it
Floating floors develop bounce and their joints work loose. Bonded floors have hollow spots where adhesive never made contact, which sound drummy underfoot and eventually debond. Vinyl telegraphs every ridge and screw head as a visible line. None of these are warranty claims against the flooring — they are subfloor failures, and manufacturers exclude them.
How we price it
We survey with a straightedge and a moisture meter and put levelling on the quote as its own line with the area, method and rate. If your subfloor is genuinely flat, that line reads zero. We would rather show you the measurement than pad a per-square-metre rate.