Tiling with under-floor heating or under-tile warming

One of the most common reasons for problems with the installation of an under-tile warming system is damage made during fitting. When covering the wires with adhesive it is quite easy to accidentally cut a wire with the trowel.



Cement-based adhesives (and grouts) set hydraulically i.e. water is involved in the hardening reaction. If the adhesive is allowed to dry out before it has properly hardened it will tend to be weak and crumbly. It is important that the heating system is off when tiles are fixed and remains off until the adhesive and grout have fully cured.

8.1 SOLUTIONS: Tiling onto electrical under-tile warming mats
Highly polymer-modified adhesives and grouts such as weber.set rapid SPF and weber.joint wide flex have enough flexibility when set to accommodate the thermally induced movements. When applying an electrical under-tile warming system, weber.niv floor can be used to cover/protect the wires that otherwise could get damaged during application of the adhesive. Electrical systems that are powerful enough to heat the room are normally buried under a 65 mm screed, which acts as a thermal reservoir. With these systems the adhesive is applied directly to the screed.



8.2 SOLUTIONS: Tiling onto electrical under-tile warming mats
Highly polymer-modified adhesives and grouts, such as weber.set rapid SPF and weber.joint wide flex have enough flexibility when set to accommodate the thermally-induced movements associated with under-tile warming on timber substrates. weber.niv dur can be used to protect the warming elements prior to tiling and also helps stabilise movement in the floor.



8.3 SOLUTIONS: Tiling onto under-floor heating pipes
Normally, piped heating systems are installed on top of insulation and buried in a reinforced cement/sand floating screed of not less than 65 mm thick. If a polymermodified levelling screed is used it must cover the pipes by a minimum of 10 mm. Highly polymer-modified adhesives and grouts such as weber.set rapid SPF and weber.joint wide flex have enough flexibility when set to accommodate the thermally-induced movements associated with under-floor heating pipes.