The world's largest supplier of underfloor heating

Most common issues can be answered by the questions below.

Our technical staff are fully qualified electricians and plumbers and can offer expert advice on any additional issues you may have.

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Tile Adhesive & Levelling

Levelling compound is designed for making an existing floor flat and level, where it may be otherwise undulated, bumpy, uneven or unlevel. It is essential in flooring preparation and makes life a whole lot easier if fixing tiles or vinyl floor finishes.

When used with underfloor heating it encapsulates and covers the heating cables or pipes providing a smooth flat base, which makes installing the floor finish far simpler. It also provides mechanical protection for the heating products when installing the floor finish, so there is no chance of damaging the heating products when tiling or laying the floor covering.

Nearly all flooring adhesives are installed using a notched trowel. The size of the notching is important because it ensures you have adequate suction/adhesion between the products and the floor. We recommend when fixing insulation boards to a floor you use a trowel with a notch between 6-10mm (depending on roughness of floor). A 6-10mm notch will produce a bed of adhesive between 3-5mm thick once compressed. It is essential that all floors are primed suitably before applying any tile adhesive.

Working time is the amount of time you will have to apply the tile adhesive to the floor and fix the tiles or insulation boards before the mix becomes too dry to work with or begins to set. Working time is affected by temperature, humidity, and porosity of the subfloor. Please consult a tiler or our technical team if unsure.

There can be several reasons as to why this can happen. 90% of the time it relates to site conditions, such as room and product temperature, lack of air flow, dew point etc. These conditions will influence ALL types of levelling compounds overall.

It is imperative that you prime the substrate prior to installing levelling compound or tile adhesive. We strongly recommend that you prime all subfloors with a suitable primer. If unsure which primer to use please call us.

Due to the nature of underfloor heating, the tile adhesive and levelling compound around the underfloor heating cables will be continually expanding and contracting. Over time this would cause a standard adhesive or leveller to crack, and the tiles may move or crack. A flexible grout is also required when grouting over underfloor heating systems.

Self levelling compound products will always specify the thickness guidelines that they are best suited to on the bag. These thickness recommendations highlight how thick the levelling can be poured in one go.

For example Ultra’s ‘ProLevel Two’ is suitable for a single pour in thicknesses between 2mm-15mm, whereas Ultra's 'Pro Level One' can be installed between 3mm-60mm.

For covering electric underfloor heating cables or pipes prior to tiling, it is recommended that the levelling compound should be applied at 6mm. If using a softer floor finish such as vinyl we recommend a minimum thickness of 10mm.

A 20kg thickness of levelling compound can cover between 1.2m2 to 5m2 depending on the thickness it is installed at. For a 6mm thickness it will cover 2.5m2, for a 3mm thickness it will cover 5m2. At 10mm thick it will cover 1.2m2. Please use our levelling compound calculator to work out how much you will need for your project.

Yes, you can install multiple layers of levelling compound. It is always best to do this with the same type of levelling compound, as using a stronger type over a weaker type can have detrimental effects causing the weaker layer to be loosened and potentially cause cracking. Each time you pour some levelling compound you must always ensure that you prime each base before hand.

Depending on the bed thickness used, tile adhesive will cover 5m2 at 3mm bed. Or cover 2.5m2 with a 6mm bed. A 3mm bed is produced by using a 6mm notch trowel as the material is pressed onto the tile adhesive it will squash into a 3mm bed.

Tile adhesive is most commonly cement based, however you cannot use cement with sand

We recommend using a minimum 6mm notched trowel when fixing the insulation boards, meaning a 3mm bed should be calculated. A 20kg bag of tile adhesive with a 3mm bed will cover approximately 4.5m2.

Please find our tile adhesive calculator on the following link: Tile adhesive calculator

We recommend when covering underfloor heating using a minimum of 6mm levelling compound prior to tiling or a minimum of 10mm levelling compound for any other floor finish.
Please find our levelling compound calculator on the following link:

Levelling calculator