Under Tile Heating: Solution to Common Problems

Under tile heating is a type of floor heating system where electric in floor heaters get installed just below the tiles. The heater consists of a thin continuous cable made from a heating element and woven into a mat-like mesh. Under tile heating is a common means of heating the tiled floors of various rooms of the house such as the bathrooms and kitchens during the winter season. However, like any other under floor heating method, under tile heating has some issues that arise from various installation factors. Below are elaborations of these problems and how to solve them.

Tile movement

As a result of the expansion and contraction of the adhesive that connects the tiles caused by turning on and of the under tile heating system, the tiles often become uneven or sometimes break off from the adhesive. The issue arises from the adhesive agent expanding and contracting at different rates than the tiles it holds, thus at times the adhesive yields and lets lose the tiles. A solution to this problem is to use highly modified polymer adhesives and grouts which have a substantial flexibility that can facilitate thermally induced movement.

Wire damage

During the installation of the under tile heating system, quite often the wiring gets damaged during the adhesive fitting process where a contractor may accidentally damage the wiring using a trowel. Unfortunately, wire damage is usually detected after the tiling already gets completed and thus to repair the damage, the entire floor or parts of it have to get undone. Signs of wire damage include cold sections on the tile floor when the heating system gets turned on because the wiring under the section got damaged. Thus, it cannot provide sufficient heat.

Once again, the solution lies in utilising a polymer modified adhesive. In addition to stabilising thermally induced movements, the adhesive also protects the heating elements prior to the tiling process. However, it is only effective if the adhesive gets applied to a minimum thickness of 10 mm from the tiles. Additionally, after the tiles get laid, the floor should not get stepped on for up to three hours to allow the adhesive to stabilise and solidify.

Weakening the grout and adhesive

Irrespective of the adhesive (cement-based or polymer) used to install the tiles; if it is not allowed to stabilise there will be issues with the floor. For instance, cement-based adhesives require water for the hardening process. Thus, if the under tile heating system gets turned on before the hardening process completes, the water evaporates. Without water, the adhesive dries up and cracks as opposed to stabilising. Thus, when laying the tiles above the under tile heating system, it is vital to refrain from turning the system on until the hardening is complete.