Special Who has levelling products which dry rapidly?

EVENNESS AND PROTECTION

THE HOW AND WHAT OF USING (FAST-DRYING) LEVELLING AGENTS

Luc Wouters (business developer in floor technology for Belgium at Bostik)

‘You always have to see high-speed drying in its context.’

Bostik specialises in adhesive systems and its products are used worldwide in several applications, from production and industrial assembly to hygienic disposables. The wide range also has solutions for the building industry, from new work to renovation, in both residential and commercial settings.

Bostik’s construction solutions also include an extensive range of levelling compounds. Luc Wouters, business developer in floor technology for Belgium, is the ideal person to tell us about this range. Luc has over 34 years of experience at Bostik and spends his working days giving and offering advice for substrate preparation and training courses. Luc explains: ‘Floor technology includes all products for repairs to covering floors, damp screens, levelling agents, and wall and floor adhesives. Bostik has products for all phases of a project and suitably adapted materials.’

Ultra-high-speed is not always necessary

‘Analyse the base and the floor,’ is Luc’s first piece of advice. ‘The levelling compound used depends on the type of floor. Whether you fit ceramics, carpet, PVC, linoleum, or parquet, each floor has specific requirements which you have to consider.’ Features such as drying time, required layer thickness, strength, and flexibility have to be taken into account. And so, ultra-high-speed drying levelling compounds are not necessarily the ideal solution.

‘A completely flat base is a necessity with a flexible floor covering such as PVC or linoleum in order to achieve a tight result. Adhesives cannot level out any unevenness. With parquet, it’s a different story. A higher adhesive consumption, and therefore a thicker layer of adhesive, means you can eradicate unevenness. Moreover, with solid parquet, great compressive and tensile strength are essential because the wood continues to work into the base. And so, each installation needs the right leveller.’

As we’ve already said, the layer thickness is another requirement. Each levelling compound has its own maximum applicable layer thickness. Luc comments: ‘In practice, not every base is uniformly flat, so it can happen that in one corner you have to absorb 4mm, whilst you have a much greater difference in another corner. The Bostik levelling compound SL C940 XL (SL = Self-Levelling and C stands for cement-bound) even goes up to 5cm thick. The SL C780 FLEX is ideal for levelling a wooden base. This is a fibre-reinforced leveller with greater bend strength.’

The next piece of advice for professionals is always to respect the stated dose with water: ‘The last thing you want is a powdery end result. And so, you stick strictly to the prescribed quantity of water. Bostik always indicates these recommendations clearly on the pack.’

Look at the use

Originally, high-speed-drying levelling compounds were developed for application in retail and public areas where renovations have to be carried out quickly and efficiently. The closing time has to be kept to a minimum. Opting for a high-speed-drying levelling compound means that you can fit a new carpet or tile floor within two to four hours. The fastest-drying levelling compound from Bostik is the SL C990 SPRINTER. ‘Under perfect atmospheric conditions you can fit stone or carpet after barely two hours and a PVC floor such as LVT strips, for instance, after four hours.’

However, linoleum or parquet require a perfectly dry base. Both products are simply too sensitive to moisture. And so, it is recommended to wait 24 hours before you fit the floor, so there’s little point in using a high-speed-drying levelling agent.’

Developments and the environment

Finally, we consider innovations in the field of levellers. ‘On the market generally, but also especially at Bostik, lots of effort is made to offer ecological solutions. For instance, all our levelling compounds have at least one emission certificate, either EC1 or even EC1+. And so, they are absolutely ideal for use with green projects (BREEAM and LEED).’

Photo – Bostik

The attached testimony clearly defines the difference between fast-drying levelling agents and ‘ordinary’ levelling agents. To make things clear, it’s necessary first to have a good grasp of what a levelling agent actually is. Amongst other things, we’re going to verify how you apply a levelling floor, why you fit it, how thick it has to be, and which substrates are suitable.

A levelling floor is a floor which levels itself and comprises mainly cement and synthetic resin. These raw materials make the floor extremely strong and flexible, so it won’t easily crack or burst. Levelling floors are often used to level out existing substrates and to prepare them ideally for the finish.

Levelling and protecting

As you know, there are diverse sorts of levelling agents on the market. Some of them will be particularly suitable in combination with concrete floors, whilst other products do particularly well with wooden substrates. You should remember that levelling floors are often used as preparation for a different type of floor, such as a cast floor.

What you shouldn’t forget is that a levelling floor is not only fitted to level the subfloor completely, but also that it serves to protect the floor finish. It’s important that the substrate is perfectly level, especially with thin floor coverings such as Marmoleum and vinyl. After all, any unevenness will show clearly through the floor covering. Moreover, sharp stones in the subfloor can damage the floor covering. Think also of thin ceramic tiles which can crack as a result of concentrated loads.

Preparation

Good preparation is half the work and that applies no less to levelling agents. Therefore, never forget to start with a carefully cleaned and grease-free subfloor. Dust, dirt, and unevenness must be avoided at all costs and, in addition, the floor has to be completely dry. If there are still any cracks and joints, don’t forget to seal them. You can use a kit or PUR for the latter job.

As for the application, you apply a special primer first. This makes the adhesion of the levelling agent even more efficient. The latter is essential with tiles, for instance, to get a good end result. Then, you stir thoroughly the levelling grout, which is made in line with the instructions, before the application because you want to avoid lumps at all costs. The levelling agent is then spread evenly over the tiles.

Limited thickness

Levelling agents are not cheap and since they are designed specially for levelling substrates, you keep the thickness of a levelling floor to a minimum. That’s why, in practice, you won’t find many levelling floors thicker than 2-3cm, and usually they are only 1 or 2mm thick. The precise layer thickness also depends on the subfloor and type of levelling agent. One more point: Since a traditional cement covering floor takes longer to dry than a levelling floor, people often add a drying time accelerator to the cement mix. This can reduce the drying time considerably, so that the works can start sooner.

Suitable substrates

In a previous edition we considered the types of substrates on which levelling agents are used, but let’s repeat ourselves briefly. Remember that basically a levelling agent can be applied to any sort of substrate, provided that it is stable enough and watertight. Tile floors or concrete floors are good examples. Wooden floors, too, may be suitable, but remember that floorboards must be secure with no joints between planks. Moreover, joints and cracks between wall joints must be sealed carefully with a kit or PUR foam. Thankfully, a levelling agent is slightly elastic and bridges cracks.

Sources: gepolierdebeton.be and gepolierdebetonvloer.be

Bona

All suitable for floor heating:

Bona H600 is a cement-bound, acrylic polymer-reinforced, selflevelling, and rapid drying levelling agent for use under mosaic parquet, engineered parquet, multilayer parquet, and solid parquet. It is also suitable for use under elastic floors, textile floors, and solid cork tiles. Bona H600 can be applied in 1 treatment up to 20mm. Floor ready for use*: after about 1.5 - 2 hours; For fitting*: with 1-10mm after about 12 hours / with 10 - 20mm after about 24 hours, for elastic and textile floors. For wooden floors 24 hours (*at +20°C and max. 65% residual damp). Bona H605 is a calcium sulphate levelling agent based on Alpha hemihydrate. It yields flat and absorbent substrates for the subsequent fitting of elastic and textile floor coverings and also for parquet which is glued using Bona silane parquet adhesives. Bona H605 can be applied in 1 treatment up to 20mm. Bona H660 is a cement-bound, acrylic polymer-reinforced, selflevelling levelling agent for use under elastic floors, textile floors, and solid cork tiles. It can also be used under wooden floors. Bona H660 can be applied in 1 treatment up to 10mm. For thicker layers you should mix Bona H660 with dry quartz sand.

Chimiver

RASOCHIM FAST Fast drying cementitious self-levelling for interior works of industrial, commercial and public floorings up to 30 mm thicknesses RASOCHIM FAST is a thixotropic cement smoothing for floors and walls with thicknesses up to 30 mm. It is a quickdrying cement grey powder composed of special cement bind, it can be used only indoor. RASOCHIM FAST mixed with water becomes a thixotropic creamy paste, easy to work with high adhesion to supports. The product hardens without shrinking, without forming slits or cracks, with rapid development of mechanical resistance. RASOCHIM FAST has a high resistance to compression, abrasion and to the action of wheelchairs. It can apply on cement screed,old plaster, not-absorbent shiny surfaces, concrete, etc. In accordance with european EN 13813 it is classified CT-C35-F7A22-B2,0. Also suitable for heated subfloors, requiring a fast hardening and drying.

Tover

In its range for the preparation of indoor substrates, Tover offers a levelling compound full of advantages: Rockfloor F10. Its main characteristics are a long self-levelling time, the possibility of applying 10 mm thickness per coat and the possibility to lay the parquet only after 24 hours. Reinforced with fibres, it is particularly strong and its final rough surface improves the adhesion of glues. It is perfectly suitable for underfloor heating. In order to increase the adhesion of the levelling compound to the screeds, we recommend to use the water-based promoter Primer C4.