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Self levelling and smoothing compounds from Ardex, Mapei, Sika, Roberts, MJS and Lanko that create a flat base before tiles, vinyl, carpet or timber go down.
Thickness
Compounds range from 1mm skims to Ardex K900BF, which fills up to 90mm in one application.
Timber
Ardex K65 and Roberts FlexiFlo are fibre reinforced for levelling timber subfloors before new flooring.
Speed
Mapei Ultraplan Fast Track takes light foot traffic after about 1 hour and resilient flooring after 2 hours.
Outdoors
Ardex K301 resurfaces internal and external concrete and is formulated to resist sun, rain, heat and cold.
A self leveller is a cement based compound, mixed with water or with a latex liquid in some kits, then poured or pumped so it flows out into a smooth, flat surface. It corrects hollows and rough slabs before floor coverings go down, and most are a preparation layer, not a finished floor.
The biggest difference between products is how thick each can go in one application. Mapei Novoplan 21 and Mapei Ultraplan Fast Track run from 1 to 10mm and Mapei Ultraplan from 1 to 15mm. Ardex CL30 goes from 3 to 30mm and Roberts UltraFlo and EcoFlo from 1 to 30mm. Mapei Ultraplan Trade reaches 40mm, and Ultraplan Renovation starts at 3mm. Sikafloor Level Ultra goes to 50mm and Ardex K80 from 5 to 50mm, with Ardex aggregate above 10mm. For deeper work, Mapei UC Leveller reaches 70mm and Ardex K900BF Pumpable Bulk Fill Leveller 90mm.
The substrate matters too. Ardex K65, Roberts FlexiFlo and Mapei Ultraplan Renovation are made for use over timber, and Ardex K60 Arditex bonds without priming in most applications, including over existing tiles. Ardex K301 resurfaces internal and external concrete, while Mapei Nivorapid and Max Prep Ramp-It handle repairs and patching. Drying times differ from product to product, so plan the job around the data sheet.
| Product | Goes over | Depth in one pour | Walk on | Ready for flooring |
|---|---|---|---|---|
| Ardex CL30 | Concrete | 3 to 30mm (40mm with Ardex aggregate) | About 3 to 4 hours | Tiles once walkable; carpet 24 hours; vinyl 48 hours |
| Ardex K12 | Concrete | 1.5 to 35mm | 2 to 3 hours | Tiles once walkable; others 18 hours |
| Ardex K125 | Concrete | 2.5 to 15mm (25mm with Ardex aggregate) | From 4 hours | Tiles 4 hours; others 18 hours |
| Ardex K15 | Concrete | Feather edge to any depth | 2 to 3 hours | Tiles once walkable; others 16 hours |
| Ardex K275 | Concrete | 2 to 25mm (40mm with aggregate) | From 4 hours | Tiles 4 hours; others 16 hours; glued-down timber 72 hours |
| Ardex K60 Arditex | Concrete, timber, existing tiles | Feather edge to 12mm (30mm with Ardex aggregate) | From 2 hours | Tiles 4 to 5 hours; vinyl 24 hours |
| Ardex K65 | Concrete and timber | 3 to 20mm (50mm with aggregate on concrete) | 2 to 3 hours | Carpet 24 hours; vinyl 48 hours; timber 72 hours |
| Ardex K80 | Concrete | 5 to 50mm | About 2 hours | Can be left as the floor surface; coat after 24 hours |
| Ardex K301 | Concrete, inside and outside | 2 to 20mm | 2 to 3 hours | Carpet 24 hours; vinyl 48 hours |
| Ardex K900BF | Concrete | 3 to 90mm | About 4 hours | Base layer only; smoothing coat from 16 hours |
| Mapei Novoplan 21 | Concrete only | 1 to 10mm | 3 to 4 hours | 24 to 48 hours, by thickness |
| Mapei Ultraplan | Concrete, existing tiles | 1 to 15mm (at least 3mm under timber) | About 3 hours | Tiles 3 hours; others 12 hours |
| Mapei Ultraplan Fast Track | See data sheet | 1 to 10mm | About 1 hour | About 2 hours (tiles, stone, vinyl, timber) |
| Mapei Ultraplan ECO | Concrete, existing tiles | 1 to 10mm (at least 3mm under timber) | About 3 hours | Tiles and vinyl 12 hours; timber 24 hours |
| Mapei Ultraplan Trade | Concrete only | 3 to 40mm | 3 to 12 hours | See data sheet |
| Mapei Ultraplan Renovation | Concrete and timber (prime timber with Eco Prim Grip) | 3 to 50mm | 4 to 6 hours | 1 to 3 days, by thickness |
| Mapei Planex HR Maxi | Concrete inside and outside, even damp | 3 to 40mm | See data sheet | Tiles 3 hours; stone 24 hours; others 24 to 72 hours |
| Mapei UC Leveller | Concrete only | 3 to 70mm (aggregate over 40mm) | About 12 hours | Tiles, carpet, floating floors 24 hours; vinyl needs 3mm Ultraplan on top |
| Mapei Nivorapid | Concrete; timber with Latex Plus added | 1 to 20mm | 60 to 90 minutes | 4 to 6 hours |
| Roberts UltraFlo | Concrete, existing tiles; not particle board or strip timber | 1 to 30mm | 2 to 3 hours | 12 hours for glued-down coverings |
| Roberts FlexiFlo | Concrete, timber, particle board | 1 to 20mm | About 3 hours | Glued-down coverings 12 to 24 hours; timber 48 hours |
| Sikafloor Level Top | Concrete | 1 to 30mm (50mm with aggregate) | See data sheet | Sealed coverings such as vinyl 18 hours |
| Sikafloor Level Ultra | Concrete inside; outside only under a roof or over a waterproofing membrane | 1 to 50mm | See data sheet | Tiles 5 to 6 hours; moisture-sensitive floors 7 to 8 hours |
| Sikafloor 4020 FiberLevel | Concrete, timber, existing tiles | 3 to 20mm | About 2 hours | Tiles 5 to 6 hours; moisture-sensitive floors 6 to 7 hours |
| Max Prep Level-It L25 | Concrete | 2.5 to 25mm (40mm with aggregate) | About 3 hours | Tiles once walkable; carpet and vinyl 24 hours |
All of these come in 20kg bags, except Ardex K60 Arditex, a 24.8kg kit of powder and latex liquid, and Mapei Nivorapid, which also comes in 5kg. For Roberts EcoFlo, check the data sheet for depth and drying times.
Start with what is underneath. Most levellers are made for concrete. For a timber subfloor, choose one made for timber, such as Ardex K65 or Ardex K60 Arditex, which also goes over existing tiles. Roberts FlexiFlo, Mapei Ultraplan Renovation and Sikafloor 4020 FiberLevel also suit timber. For concrete outside, Ardex K301 and Mapei Planex HR Maxi are made for external use, and Sikafloor Level Ultra can go outside under a roof or over a waterproofing membrane.
Then measure how deep the worst hollow is. For a skim of a few millimetres, a smoothing compound such as Ardex K12 or K15 gives a fine finish. For deep fills, Ardex K900BF goes up to 90mm in one pour as a base layer, topped with a smoothing compound. Times to walk on and to lay flooring change with temperature, depth and the floor covering, so check the data sheet for your product before you book the next trade.
Common Questions
It depends on the product. Single-application limits in this range start at 10mm for Mapei Novoplan 21 and Ultraplan ECO. Mapei Ultraplan Trade reaches 40mm, Sikafloor Level Ultra and Ardex K80 50mm, Mapei UC Leveller 70mm and Ardex K900BF 90mm. Some products allow aggregate for deeper pours, as Mapei does for UC Leveller above 40mm, so check the data sheet.
Almost always. Roberts specifies a diluted coat of Roberts R48 Universal Primer on porous substrates under EcoFlo, and Mapei names Eco Prim Grip for timber under Ultraplan Renovation. Ardex K60 Arditex is an exception, as it bonds without priming in most applications. Whatever leveller you choose, use the primer and dilution its data sheet specifies for your substrate.
Yes, with a product made for it. Ardex K65 is fibre reinforced for strip timber, particleboard and plywood from 3 to 20mm. Roberts FlexiFlo is a flexible, fibre reinforced leveller from 1 to 20mm, and Mapei Ultraplan Renovation suits old or new timber floors from 3 to 40mm. Timber must be clean and firmly fixed. An unreinforced cement topping can crack when timber moves.
Times differ widely. Sikafloor Level Ultra takes tiles or stone after 5 to 6 hours at 23°C, and Mapei Ultraplan takes ceramic tiles after 3 hours and other coverings after 12 hours. Ardex K15 Microtec is ready for floorcoverings after 16 hours, with Ardex aggregate mixed in above 10mm, and Mapei UC Leveller needs 24 hours. Timber can need longer, as with the 24 hour wait Roberts gives for timber over UltraFlo.
Several manufacturers set a minimum. Roberts UltraFlo, Roberts FlexiFlo and Mapei Ultraplan ECO each call for at least 3mm of leveller before timber flooring over concrete, as a thinner skim may not give a stable base. Also confirm the slab is dry enough before you start, because a leveller is a smoothing layer, not a moisture barrier.
Our team can help you match a levelling compound and primer to your substrate, the depth you need and your floor covering. Get in touch for expert advice and product data sheets.
Get in touch for expert advice, samples and trade pricing.
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