Floor Levelling Compound Coverage, Bags & Cost Estimator – Updated 2026 Prices
Enter your room dimensions and screed depth to calculate the number of bags, volume, weight, and cost of self-levelling screed or floor levelling compound for your project. Results include a 10% wastage allowance and 2026 UK price estimates for all main screed types.
Self-levelling screed (also called self-levelling compound, floor levelling compound, or flowing screed) is a specially formulated cementitious or calcium sulphate (anhydrite) product that, when mixed with water and poured onto a prepared floor surface, flows under its own weight to form a perfectly level surface. Unlike traditional sand and cement screed (which must be tamped and floated to achieve level), self-levelling products seek their own level by gravity, making them significantly faster to install and capable of achieving much thinner minimum depths. They are used in both residential renovation (levelling uneven existing floors before laying new floor coverings) and new build / extension construction (providing a flat, level base for floor finishes over insulation or underfloor heating).
The UK floor levelling market in 2026 is dominated by two main product categories: bagged self-levelling floor compounds (mixed on site in a bucket or forced-action mixer and poured from a bucket or pump) and pumped liquid screeds (either anhydrite/calcium sulphate or cementitious, mixed at a specialist truck and pumped directly into the building). Bagged products are used for renovation projects and smaller areas (typically up to 50–100 m²), while pumped liquid screeds are the standard for new build and extension floor construction where larger areas (50 m²+) need to be screeded efficiently.
Choosing the correct product for your application requires careful consideration of: the required depth (most bagged self-levelling compounds are limited to maximum depths of 15–50mm per application; pumped screeds can achieve 25–150mm); the substrate type (all self-levelling products require priming with a compatible primer; some products are not suitable for timber subfloors without specialist preparation); the underfloor heating system (anhydrite screeds have excellent thermal conductivity for UFH but cannot be used in wet rooms); and the required drying time (rapid-set products allow foot traffic in 1–4 hours; standard products typically require 24 hours for foot traffic and 28 days for full moisture drying before impermeable floor finishes).
Self-levelling screed resources UK 2026: Ardex UK | Weber Building Solutions | Mapei UK | Checkatrade – Find a Screeder | NHBC Standards
Coverage is based on a typical bagged self-levelling cementitious compound with a mixed density of approximately 1.6 kg/litre. Coverage varies slightly between products — always check the manufacturer's datasheet.
| Depth (mm) | Coverage per 25kg Bag (m²) | Bags per 10 m² | Bags per 25 m² | Bags per 50 m² | Typical Application |
|---|---|---|---|---|---|
| 3mm | 5.2 m²/bag | 2 bags | 5 bags | 10 bags | Ultra-thin skim / micro-levelling |
| 5mm | 3.1 m²/bag | 4 bags | 9 bags | 17 bags | Standard thin levelling skim |
| 10mm | 1.6 m²/bag | 7 bags | 17 bags | 33 bags | Medium renovation levelling |
| 15mm | 1.0 m²/bag | 10 bags | 25 bags | 50 bags | Thicker renovation levelling |
| 20mm | 0.78 m²/bag | 13 bags | 33 bags | 65 bags | Heavy levelling / deep fill |
| 25mm | 0.63 m²/bag | 16 bags | 40 bags | 80 bags | Minimum over UFH; new build thin screed |
| 40mm | 0.39 m²/bag | 26 bags | 64 bags | 128 bags | Standard domestic UFH screed |
| 50mm | 0.31 m²/bag | 32 bags | 80 bags | 161 bags | Standard new build floor screed depth |
| Screed Type | Min–Max Depth | Foot Traffic | Floor Finish | UFH Compatible? | Wet Room? | Installed Price (m²) | Notes |
|---|---|---|---|---|---|---|---|
| Bagged SL compound (standard) | 3–50mm | 2–4 hrs | 24–48 hrs | Limited (check) | Yes (with waterproofing) | £15–£30/m² | Ardex K10, Weber 4310, Mapei Ultraplan |
| Rapid-set bagged SL compound | 3–30mm | 1–2 hrs | 3–24 hrs | Limited | Yes (with WP) | £25–£50/m² | Ardex K14, Bal Fastfix; premium pricing |
| Anhydrite liquid screed (pumped) | 25–150mm | 24–48 hrs | 4–6 weeks (dry) | Yes – excellent | No | £20–£35/m² | Gyvlon, Gyproc, Cemfloor; dominant new build product |
| Cementitious liquid screed (pumped) | 30–100mm | 24–48 hrs | 3–4 weeks (dry) | Yes – good | Yes | £22–£38/m² | Suitable where anhydrite not appropriate |
| Traditional sand & cement screed | 25–75mm | 24–48 hrs | 4–6 weeks (dry) | Yes (bonded) | Yes | £12–£22/m² | Lowest material cost but slower and more labour-intensive |
| Fibre-reinforced bagged screed | 5–50mm | 2–6 hrs | 24–48 hrs | Limited | Yes (with WP) | £18–£38/m² | Better crack resistance; ideal for commercial renovation |
| Lightweight pumped screed | 25–100mm | 24 hrs | 2–4 weeks | Yes | Limited | £18–£30/m² | Reduced dead load; useful on timber decks and mezzanines |
| Product Type | Bag Size | Price per Bag (2026) | Coverage at 5mm | Coverage at 10mm | Approx. Price per m² at 5mm | Notes |
|---|---|---|---|---|---|---|
| Standard SL compound (economy) | 25kg | £8–£12 | 3.0–3.2 m² | 1.5–1.6 m² | £2.80–£4.00/m² | Own-brand / economy brands from builders merchants |
| Standard SL compound (premium) | 25kg | £12–£18 | 3.0–3.5 m² | 1.5–1.75 m² | £3.50–£6.00/m² | Ardex K10, Weber 4310, Mapei Ultraplan |
| Rapid-set SL compound | 25kg | £18–£35 | 3.0–3.2 m² | 1.5–1.6 m² | £6.00–£12.00/m² | Ardex K14, Bal Fastfix |
| Fibre-reinforced compound | 25kg | £14–£22 | 3.0–3.2 m² | 1.5–1.6 m² | £4.50–£7.50/m² | Better crack resistance |
| Self-levelling underlayment (feather finish) | 25kg | £12–£20 | 4.5–6.0 m² at 3mm | n/a | £2.50–£4.50/m² at 3mm | Ultra-thin finishing skim; very smooth surface |
| Acoustic self-levelling compound | 25kg | £18–£30 | 2.5–3.0 m² | 1.2–1.5 m² | £6.00–£12.00/m² | With integral resilient layer for sound insulation |
| Anhydrite liquid screed (pumped) | Per m³ pumped | £60–£120/m³ material | Installed at £20–£35/m² (includes pump, labour, material) | Minimum areas apply – typically 50–100 m² | ||
All prices are indicative 2026 South East England supply-only estimates excluding VAT and delivery. Deduct 8–12% for North England, Scotland, and Northern Ireland. Add 10–18% for Greater London. Prices vary significantly between suppliers and product quality levels — always compare at least two quotes and confirm with manufacturer datasheets for coverage rates.
Priming is the most critical preparatory step before applying any self-levelling compound. The primer: seals porous substrates to prevent the substrate absorbing water too quickly from the compound (which causes premature setting, surface dusting, and adhesion failure); improves bond between the compound and the substrate; and consolidates dusty or weak surfaces. Use the primer specified by the compound manufacturer — mixing brands of primer and compound is risky. Apply primer evenly and allow to dry until just tacky (typically 30–60 minutes) before pouring.
Anhydrite (calcium sulphate) liquid screed dominates the UK new build market in 2026 because of its excellent flow, minimal shrinkage cracking, and outstanding thermal conductivity for UFH (approximately 1.8–2.0 W/mK vs 1.2–1.5 for cementitious). However, anhydrite cannot be used in wet rooms (bathrooms, kitchens) as it is not water resistant — it will soften and delaminate if permanently wet. In wet room locations, use cementitious liquid screed or traditional sand and cement screed.
Self-levelling screeds have two distinct time stages that are often confused. Curing is the chemical hardening process — most screeds achieve sufficient structural strength for foot traffic in 1–48 hours and full compressive strength in 7–28 days. Drying is the evaporation of surplus mix water to a level acceptable for floor finishes — typically 75% RH or less. Drying takes far longer than curing: a 40mm screed typically takes 4–6 weeks to dry sufficiently for impermeable floor finishes in normal conditions (20°C, 50–60% RH).
A widely used rule of thumb for screed drying time is 1mm depth = 1 day drying time for the first 50mm, then 2 days per mm above 50mm, at standard conditions (20°C, 50–60% RH). This gives: 5mm = 5 days; 25mm = 25 days; 50mm = 50 days; 75mm = 100 days. In practice this is a guide only — cold, damp conditions significantly extend drying; good ventilation, dehumidifiers, and heating can accelerate it. Always test with a calibrated hygrometer before laying impermeable floor finishes.
Before laying any floor finish (particularly tiles with impermeable adhesive, LVT, sheet vinyl, or engineered wood), the screed moisture content must be tested with a calibrated hygrometer. The standard UK threshold is 75% RH (some floor finish manufacturers specify 65% RH for engineered wood or 80% RH for certain tile adhesives — always check). A surface hygrometer reading above the threshold means the screed is not dry enough — laying the floor finish will trap moisture, causing adhesive failure, tile lifting, buckling of wood floors, or mould growth beneath impermeable coverings.
All floor screeds must be isolated from the surrounding walls and structural elements using a perimeter edge strip — typically 5–8mm closed-cell polyethylene foam strip stuck to the wall before screeding. This allows the screed to expand and contract thermally without cracking at the perimeter and prevents sound transmission through the screed to the walls. Edge strip is also required around any fixed elements penetrating the screed (column bases, pipe ducts). Without edge strip, screed regularly cracks at the perimeter within the first year.
When screeding over underfloor heating pipes, the minimum cover (from the top of the pipe to the finished screed surface) is critical. Anhydrite screed: minimum 25mm cover above the top of the pipe (so if pipes are 16mm diameter on a 25mm clip system, the total depth is approximately 50–55mm). Cementitious screed: minimum 30–40mm cover above the pipe. Traditional sand and cement: minimum 40mm cover. Insufficient cover causes cracking along the pipe lines and uneven surface temperatures. Always commission UFH system before laying the floor finish to check for air locks.
Any screed area larger than approximately 40–50 m² or with a dimension exceeding 8m in any direction should be divided into bays using movement joints. Anhydrite liquid screeds have very low shrinkage and rarely need intermediate movement joints in areas up to 300 m²; however, they must still be isolated from walls and fixed structures. Cementitious screeds and sand and cement screeds are more prone to shrinkage cracking and require movement joints at approximately 6–8m centres in each direction. Movement joints in the screed must be carried through to the floor finish above.
The water-to-powder ratio is critical for bagged self-levelling compounds — too much water weakens the set compound and causes dusting and reduced bond; too little water prevents adequate flow and levelling. Always use the exact water quantity specified in the manufacturer's datasheet. Mix with a drill and paddle or forced-action mixer — never hand mix. Mix for the full recommended time (typically 2–3 minutes). Pour promptly and work quickly — most compounds begin to stiffen within 15–20 minutes of mixing. Work in sections from the furthest point to the door to avoid stepping on fresh compound.
One of the key advantages of self-levelling compounds over sand and cement screed is their ability to feather down to zero at edges — allowing seamless transitions between rooms of different floor levels and tapering out level differences without creating a step. Most cementitious self-levelling compounds can be applied as thin as 3mm and feathered to approximately 1–2mm at the edges. Sand and cement screed has a minimum practical depth of approximately 25mm and cannot be feathered. This makes self-levelling compounds uniquely suitable for renovation and retrofit levelling applications.
Self-levelling compound can be applied over timber subfloors (floorboards, plywood, OSB, chipboard) but requires careful preparation. The timber must be: structurally sound with no flex or movement (any deflection will crack the screed); fully secured with screws at 150mm centres (punched 3mm below surface); all gaps and knotholes filled; and sealed with a specialist flexible floor primer (not standard SBR latex primer). Using a flexible self-levelling compound (fibre-reinforced or elasticised) is recommended over timber to accommodate minor movement. Maximum depth over timber is typically 10–15mm.
Before the floor finish can be laid over a screeded UFH system, the UFH must be commissioned — a controlled warm-up and cool-down cycle that cures the screed fully, removes residual moisture, and checks for any air locks or leaks. For anhydrite screed, commissioning typically involves: waiting 7 days after laying; then raising the UFH temperature gradually to 25°C for 3 days, then to the maximum design temperature for 4 days, then lowering gradually back to ambient over 2 days. Only after this commissioning process and subsequent moisture testing can the floor finish be installed. Failure to commission before laying the finish is a common cause of screed failure.
The quantity of self-levelling compound needed per m² depends on the application depth. For a standard cementitious self-levelling compound at a mixed density of approximately 1.6 kg/litre: at 5mm depth, approximately 8 kg (0.32 bags) per m²; at 10mm, approximately 16 kg (0.64 bags) per m²; at 25mm, approximately 40 kg (1.6 bags) per m². One standard 25kg bag covers approximately: 3.1 m² at 5mm; 1.6 m² at 10mm; 0.63 m² at 25mm. Always add a 10% wastage allowance. Use the self-levelling screed calculator above for exact quantities based on your floor dimensions and required depth.
Drying time depends on screed type, depth, temperature, and ventilation. As a guide for bagged cementitious self-levelling compounds: foot traffic typically possible after 2–4 hours (rapid-set products in 1–2 hours); laying of breathable floor finishes (carpet, wood over battens): typically 24–48 hours; laying of impermeable floor finishes (tiles, LVT, sheet vinyl, directly adhered engineered wood): typically 1mm per day drying time rule applies — 5mm screed takes approximately 5 days; 25mm takes approximately 25 days; 50mm takes approximately 50 days — all at standard conditions of 20°C and 50–60% RH. Always test with a calibrated hygrometer before laying impermeable finishes — the screed must read ≤75% RH (or the floor finish manufacturer's specified maximum). Never rely solely on elapsed time.
The key differences are in binder type, application method, depth range, and suitable applications. Bagged self-levelling compounds are cementitious (Portland cement based), mixed on-site in small batches, and are primarily designed for renovation levelling at depths of 3–50mm. They are water resistant, compatible with most substrates and floor finishes, and can be used in wet rooms. Anhydrite liquid screed (also called calcium sulphate screed or flowing screed) uses calcium sulphate (gypsum-based) binder, is pumped directly from a specialist truck into the building, and is applied at depths of 25–150mm. Anhydrite has superior thermal conductivity (excellent for UFH), flows better than cementitious products, and has minimal shrinkage — but it is not water resistant and cannot be used in wet rooms. Anhydrite is the dominant choice for new build and extension floor screeds over UFH in the UK in 2026.
Yes — priming is absolutely essential before applying any self-levelling floor compound. Without primer, the substrate absorbs water rapidly from the freshly poured compound, causing premature setting, surface dusting, pin-holing, and catastrophically poor adhesion — the screed may lift or delaminate within days. The primer: (1) seals the substrate to control water absorption; (2) bonds the fresh compound to the substrate; (3) consolidates any weak or dusty surface. Always use the primer recommended by the compound manufacturer — compatibility between primer and compound is product-specific. Apply the primer evenly, allow it to dry until tacky (typically 20–60 minutes), and then pour the compound promptly. On very absorbent substrates (bare concrete, existing sand and cement screed), a second primer coat may be needed.
Yes — self-levelling compound can be applied over existing tiles, but preparation is important. The tiles must be: firmly adhered (any loose, hollow, or cracked tiles must be removed or secured — test by tapping each tile with a hard object; a hollow sound indicates debonding); free of grease, wax, and contaminants (degrease thoroughly); and mechanically keyed (lightly sand or use a diamond disc grinder to key the surface — polished tiles need aggressive keying). Apply a specialist tile bonding primer (such as Ardex P 82, Weber Primer D, or Laticrete 254 Platinum primer) rather than standard SBR latex. The self-levelling compound will bridge the grout lines if applied at 3mm or more. If tiles are significantly raised above the surrounding floor, a thick-section compound (10–15mm minimum) is more appropriate than an ultra-thin skim.
Anhydrite screed (also called calcium sulphate or flowing screed) is a floor screed made with a calcium sulphate (gypsum-derived) binder rather than Portland cement. It is supplied as a pumpable liquid from a specialist mixing truck and flows under gravity to produce an exceptionally flat, level surface with minimal manual finishing. Anhydrite is the preferred screed for underfloor heating in the UK because its thermal conductivity (approximately 1.8–2.0 W/mK) is significantly higher than cementitious screed (1.2–1.5 W/mK), meaning heat transfers from the UFH pipes to the floor surface more efficiently, reducing running costs. Additionally, anhydrite has very low shrinkage (less than 0.05%), so cracking along pipe lines is very rare — a significant advantage over sand and cement screed. The critical limitation is that anhydrite is not water resistant and must not be used in bathrooms, wet rooms, or kitchens. The anhydrite surface must also be sanded and vacuumed before applying floor finishes to remove the surface laitance layer.
The minimum and maximum depth of self-levelling screed depends entirely on the product type and application: Bagged thin-bed levelling compounds: minimum 3mm (some feather to near zero at edges); maximum per application typically 10–25mm (build up in multiple coats for deeper applications). Standard bagged self-levelling compounds: minimum 5mm; maximum typically 30–50mm in a single application (check datasheet). Anhydrite liquid screed: minimum 25mm (35mm recommended over UFH pipes); maximum typically 150mm. Cementitious liquid screed: minimum 30mm; maximum 100mm typical. Traditional sand and cement: minimum 25mm bonded; 50mm unbonded. For renovation levelling applications (thin coats over existing floors), 3–10mm is typically used. For new build floor screeds over insulation and UFH, 40–75mm is standard.
Self-levelling screed costs vary considerably by product type and application method. For bagged self-levelling compound at 5mm depth: material cost approximately £3–£6/m² (economy brands) or £4.50–£9/m² (premium brands). Installed (supply and labour): approximately £15–£30/m² depending on floor condition, primer requirements, and contractor mobilisation costs. For pumped anhydrite liquid screed at 50mm depth: installed cost (materials, pump, and labour) approximately £20–£35/m², with a typical minimum charge of £600–£1,200 for small areas below 50 m². Pumped cementitious liquid screed at 50mm: approximately £22–£38/m² installed. Traditional sand and cement screed: approximately £12–£22/m² installed. Always request at least two quotes — prices vary significantly between contractors and between regions.
It depends on the screed type. Cementitious self-levelling compounds (Portland cement based) are inherently water resistant once cured and can be used in wet areas, provided a compatible waterproof membrane (tanking system) is applied to the screed surface before tiling. Most standard bagged levelling compounds used in renovation and tiling preparation are cementitious and suitable for wet areas. Anhydrite (calcium sulphate) liquid screed is not suitable for wet rooms under any circumstances — it will absorb water, soften, and delaminate. Always confirm the binder type with your supplier if there is any doubt. For wet rooms receiving tiles, the standard UK specification is: cementitious screed or sand and cement screed → waterproof tanking membrane → wall and floor tiles.
The waiting time between screeding and tiling depends on the screed type and depth. For bagged cementitious self-levelling compounds: tiles can generally be laid 24–48 hours after application for most compounds, using a cement-based tile adhesive that can accommodate some residual moisture. However, for large-format tiles (over 600 × 600mm), impermeable adhesives, or where rapid-setting adhesives are specified, the screed should be allowed to dry to ≤75% RH — which for a 10mm compound takes approximately 10 days at standard conditions. For anhydrite liquid screed: standard curing takes 24–48 hours; the surface laitance must be removed by sanding; drying to ≤75% RH takes approximately 1mm per day (50mm screed = approximately 50 days). UFH commissioning must also be completed before tiling. Always test with a hygrometer before tiling over any screed — premature tiling over wet screed is one of the most common causes of tile adhesion failure in UK construction.
For pumped liquid screeds (anhydrite or cementitious), you need a specialist liquid screed contractor who operates a pumped screed vehicle. These contractors are distinct from general builders and tilers — search specifically for "liquid screed contractor" or "anhydrite screed" in your area. Most pumped screed contractors have minimum area requirements (typically 50–100 m²) and serve a regional catchment area. For bagged self-levelling compound work in renovation projects, general floor preparation contractors, tiling contractors, or experienced DIYers can typically carry out the work. Check reviews on Checkatrade or TrustATrader, ask for references from similar projects, and confirm that the contractor is familiar with the specific product being used and its primer and curing requirements. Request the manufacturer's product datasheets and confirm the installation method before work begins.
Additional screed resources UK 2026: Ardex UK – Self-Levelling Compounds | Mapei UK | Checkatrade – Screed Contractors | NHBC Standards | TrustATrader