Installing Underfloor Heating
17th November 2020

A tiling installation that can take the heat

When laying tiles over underfloor heating systems, there are a few rules of thumb that should not be neglected.  Firstly, ensure that the wiring in electrical systems is fully encased in either levelling compound or adhesive.  Always use flooring compounds and adhesives with sufficient flexibility to cope with the expansion and shrinkage caused by the heat, and ensure that in-screed heating systems have been commissioned, allowed to cool and that any weaknesses in the screed have been repaired prior to tiling.  It is important to ensure that the tiles are laid on a solid bed of adhesive with no voids.  Lastly once tiling has been completed, allow the adhesive and flooring compound ample time to set before turning the heating system back on and do so gradually, so that they do not dry out before fully curing, which will cause the installation to fail.

Luckily Tilemaster Adhesives has a range of products that make all of this very easy.  Tilemaster Rapid Level 30 is a water-based, ultra-rapid setting, flexible self-levelling compound that is ready for tiling after 45 minutes and laying impervious flooring after 90 minutes.  Tilemaster LevelFlex allows tile installation after 3 hours under normal conditions.  It is a fibre-reinforced, flexible self-levelling compound which can be used at depths of 2mm to 50mm.

Where the underfloor heating system has been encased in a calcium sulphate screed, Tilemaster Anhylevel is an excellent choice as it is gypsum-based and has been specially developed for use over this type of screed.  It is a flexible self-levelling and smoothing compound that can be tiled after 24 hours. 

For the tiling, Tilemaster Adhesives has a choice of standard, semi-rapid and rapid setting products in the Setaflex range, a polymer modified, flexible cement-based wall and floor tile adhesive. Both Setaflex Standard Set and Semi-Rapid Setaflex have been specially developed to give an extended pot life, making them ideal for working with larger, difficult to manoeuvre tiles.  Tilemaster Standard Set Setaflex has a pot life of 3 - 4 hours and can be grouted after 24 hours.  The Semi-Rapid version offers a great compromise between extended workability, with a pot life of 90 - 120 minutes, and a fast setting time, as it will accept light foot traffic and grouting after 6 hours.  Where time is a priority, Rapid Setaflex is ready for grouting after 3 hours with a 30 minute pot life.  Another excellent adhesive for use with underfloor heating systems is Tilemaster Ultimate.  This is a high specification, polymer modified, highly flexible rapid setting floor and wall tile adhesive with increased adhesion properties which is also ready for grouting after 3 hours.

For tiling onto calcium sulphate screeds, following the needs for compatibility, Tilemaster also offer AnhyFix, a calcium sulphate based tile adhesive that is 100% compatible with both calcium sulphate screeds, and Tilemaster AnhyLevel, allowing a fully compatible system. 

After fixing, tiles should be grouted with Tilemaster Grout 3000, a flexible, fast setting wall and floor grout which can be used for joints between 1mm and 20mm, available in a range of 18 colours allowing you to colour match to the tile, or to use a contrasting colour as desired.