DIY: How to tile onto underfloor heating
Here's a DIY tiling job that will make your home feel all warm inside and your toes toasty, and you the star of the family for acing heated floors.
Anyone who has experienced the shock of bare toes on icy cold tiles will appreciate the benefits of underfloor heating.
Traditionally the floor covering of choice for bathrooms and kitchens, primarily because they are hardy and easy to keep clean, tiles are gaining in popularity in other areas of the house too. Because they also have a high thermal conductivity and hold heat for a long time, tile and stone floorings can be heated over 28°C, making them the perfect partner for heated floors.
The Warmup mat system of electric underfloor heating is purpose-designed for tiles. It comprises ultrathin heating mats that fit into the adhesive layer under tiles, and therefore doesn’t affect the height of the floor.
Once, you’ve prepped the floor, and affixed Warmup insulation boards using a tile adhesive, the mats can be laid. For instructions on these steps, read our blog How to install electric under floor heating.
The electric underfloor heating system must be tested by a certified electrician before any preparation or tiling work is carried out.
Laying tiles onto underfloor heating
Choosing tile adhesive for heated floors
Tiles and adhesives expand and contract with changes in temperature. However, because they expand at different rates, tiles can crack or de-bond when there is too much pressure between the tiles and adhesive.
Use a flexible adhesive that suits the type and thickness of the tiles, and mix it according to the manufacturer’s instructions.
If you’ve installed an electric underfloor heating system such as Warmup StickyMat, apply a small amount of adhesive over the heating mat with a small trowel, to stop the wires from snagging during the tiling operation, and to smooth over any gaps.
Laying the tiles over electric heating mats
Laying tiles over underfloor heating is pretty much the same as any other tiling job, that starts with applying a thick layer of tile adhesive, using the notched side of the trowel.
You can use a leftover piece of insulation board to kneel on while you are tiling. This will prevent damage to the heating mats.
Avoid tiling yourself into a corner. You don’t want to be walking over your newly-laid tiles before the adhesive has set. If you can’t avoid using the room (a hallway, kitchen or bathroom) while the tiles are drying, consider tiling the room in two stages, so you can still use it. But still tread carefully so as not to damage the heating mats on the untiled parts.
Grouting tiles with heated floors
It’s best to use a grout that has the flexibility to cope with the tiles expanding and contracting as a result of the warming and cooling of heated flooring. Do not use a utility knife to clean the grouting, as it may pierce or damage the heating mat.
After tiling
Don’t use the underfloor heating to force-dry the adhesive before it is completely cured. It will become weak and crumbly, which could lead to the tiles lifting or cracking.
In fact, don’t turn on the underfloor heat at all until seven days after completing the tiling to give the adhesive and grout enough time to dry, and even then, build up the heat slowly over a week or two.
