Why the subfloor matters
A new floor sits on what is below it. Fitters test the subfloor first and either level it or repair it, and that work is a separate line on the quote. The sources below cover how moisture is measured, what levelling and preparation cost, and how long fitting takes.
What you are paying for
When a quote says "preparation", you should ask what it covers: removing the old floor, cleaning the base, testing moisture, levelling, or all four. Each is priced separately in the guides.
When the quote changes
Citizens Advice says a trader can charge more than the quote if the trader tells you extra work is needed and you agree. Subfloor problems are the usual reason, so agree the price of repairs before the old floor comes up.
Measuring moisture in a screed
The 75% figure
The Contract Flooring Association (CFA) quotes Annex A of BS 8201: when the relative humidity falls to 80%, the water has left the coarse pores and the screed is dry enough for resilient coverings. Allowing for measurement error, the screed is considered dry when relative humidity falls to 75% or less.
Two ways to measure
A surface hygrometer box tests the surface of the slab or screed. An in-situ probe, or sleeve, tests inside the slab. The CFA note says the two methods test different sections of the slab, so two different readings are expected in the same place. The note says that when 75% is achieved at the surface, 85% is expected within the slab.
What the CFA recommends
The CFA note recommends changes to the guidance: an upper limit of 85% for the in-situ method, an equilibrium time of 24 hours instead of 72, and a minimum screed thickness of 10cm for the probe test. The note says that if the depth of the slab or screed is unknown, the in-situ method should not be used and the surface hygrometer box should be used instead. The changes are recommendations from a trade body, so ask your fitter which method and which limit apply to your product.
Wood floors
Bona's guidelines, written around BS 8201:2011, give 75% RH for a screed, or 65% RH for wood floors bonded directly to the screed. Where heating is installed, the heating must be commissioned before the boards go down. The guide to engineered wood over underfloor heating covers the warm-up.
Levelling and preparation lines
Laminate and vinyl
MyJobQuote's laminate guide gives screed levelling at around £15 per square metre and a levelling compound at £10 to £20. A seriously uneven floor is priced at £800 to £2,500. Removal of an old carpet is around £7 per square metre, and removal of tile or a glued-down floor is around £10 to £15.
Tiling
MyJobQuote's tiling guide gives floor screeding at £18 to £25 per square metre, self-levelling compound at £10 to £20, backer board supplied and fitted at £30 to £55, and tanking for wet areas at £100 to £250. Subfloor preparation has no separate price in that guide.
Carpet
Checkatrade gives floor levelling for carpet at £10 to £15 per square metre, which the costs guide lists beside the other carpet extras.
A rough levelling cost for a 12m² room
At £10 to £20 per square metre, a levelling compound for 12m² costs £120 to £240, by arithmetic from the laminate guide. A seriously uneven floor is priced at £800 to £2,500 in the same guide, so ask the fitter to say which of the two your floor needs.
Screed types and timber subfloors
Sand and cement or anhydrite
The Solid Wood Flooring Company says sand and cement screeds must be sealed with a damp-proof membrane, while anhydrite screeds must not be sealed with one because moisture harms their gypsum structure. The supplier says general cement and anhydrite screeds dry at about 1mm a day, and that a 75mm screed takes at least 75 days to reach a moisture content below 1.8% in normal conditions.
Timber subfloors
For wood on a timber subfloor the same supplier sets a timber moisture limit of 10% and joists at no more than 350mm centres. The supplier gives an evenness limit of 3mm under a 3m straight edge. You can ask the fitter to show you the reading and the straight-edge check before the boards go down.
Removing the old floor
Lifting the old floor is often priced as its own line. The figures below come from three MyJobQuote guides.
| Removal | Price |
|---|---|
| Old carpet | Around £7 per m² |
| Tile or glued-down floor | Around £10 to £15 per m² |
| Floor tiles (large or stubborn adhesive) | £8 to £15 per m²; £20 to £30 per m² |
| Laminate | £3 to £8 per m² plus £50 to £150 disposal |
| Wood floor | £40 to £180 labour plus £50 to £150 waste |
| Skip hire | £150 to £400 (tiling guide); about £220 (LVT guide) |
Why this matters to your quote
Some fitters include removal and some do not, so ask which applies. If you plan to lift the old floor yourself, tell the fitter, because the base underneath may need cleaning or levelling before the new floor goes down.
How long fitting takes
MyJobQuote's LVT guide gives labour times by room: a small bathroom of 5m² takes one day, a 12m² kitchen takes one to two days, a 13m² double bedroom takes one to two days and a 17m² living room takes two days. Its kitchen guide puts an average kitchen floor at around two days. Its tiling guide bases labour on a tiler laying 8m² to 12m² a day.
What the times assume
The times assume a prepared, level, dry subfloor. Levelling, drying a screed or lifting an old floor adds to them.
What to put in writing
Ask the fitter for a start date, a finish date and a written note of what happens if the subfloor delays the job. You will need the dates to plan furniture and access.
Before the fitter arrives
Clear the room, tell the fitter about underfloor heating, pipes or damp patches you know of, and keep the removal line on the quote if you want the old floor lifted. A fitter who knows about a problem beforehand can price it, and you avoid an argument on the day.
Questions to ask the fitter
- How will the subfloor be tested, and what is the limit for my product?
- Who levels it, with what material, and what does that cost per square metre?
- What happens to the quote if damp or damage is found once the old floor is up?
- Is removal of the old floor and disposal in the price?
The directory lists 86 carpet fitters, 74 vinyl, LVT and laminate fitters, 63 wood and parquet floor fitters and 91 floor tilers. The hire-a-fitter checklist gives the checks to run on the answers.
What this page does not cover
The page quotes BS 8201 only as quoted by the CFA and Bona, because the standard is paid. The page does not cover BS 8203 or BS 8204 text, damp-proof membranes, or timber subfloors beyond what the sources say. The CFA changes are recommendations, not a new standard, and the product maker's instructions override any general figure. Prices are UK price-guide ranges with no Wales row.