Tiling to Underfloor heating is a guide to tiling onto floors.

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With their popularity increasing by the year, heated floors are becoming the norm for tilers when starting on a job.

During the heating and cooling cycles, movement stress can build up in a heated floor.It's important that the thermal expansion of the tiled finish doesn't vary too much from the sub-floor.The stresses on rigid tile finishes are caused by small changes in expansion and contraction.In addition, in order to reduce the risks of tiles cracking or de-bonding, adequate preparation, and where applicable the floor heating system is important.The essential preparation for each system is listed here.

If tiling onto a Hot Water Pipe system, make sure the screed is completely dried.In the case of reinforced cement;sand based screeds this can range from 6 days with BAL Quickset Cement to a minimum of 3 weeks for a screed containing OPC, before the underfloor heating begins.

Surface preparation is important for anhydrite or alpha hemihydrate.The drying time can be extended if the site conditions are right.Further guidance may be sought from the manufacturer.

The heating manufacturer recommends that the screed be heated slowly at a maximum rate of 5C per day up to the maximum operating temperature.The temperature of the floor should be kept at this level for a minimum of three days to allow it to cool.

If the heating system is turned off or on in cold temperatures, the screed will be 15C before tiling begins.

When using cable systems make sure the system is compatible with the intended application areas.Kitchen, bathroom, etc.

The cables should bebedded into a self-smoothing compound.The levelling compound should be encased within the heating cables when using the BAL Rapid Mat uncoupling system.

Make sure the chosen system is compatible with the environment it is being used in.

Before tiling, the surface of the mat needs to be primed with a contact adhesive, and then tiles should be installed using the correct glue.

The movement joints and control joints should be at all the perimeters of the screed.While the screed is being laid, movement joints are formed.The full depth of the insulation should be penetrated by the movement control joints.

When tiling begins, movement joints should be incorporated.Under floor heating, floor areas should be divided up by movement joints into bays of size not greater than 40m2 with and edge length not more than 8m.

If using BAL Rapid-Mat, the mat should be separated when the movement joints penetrate through the thickness of the tile and bed.

A suitable tile glue is required when tiling onto concrete or cement.

BAL Single Part Flexible, BAL Supercover Rapidset Flex and BAL Rapid Flex One are some of the suitable adhesives.

For single layers of timber, or where plywood is less than 15mm, consider the use of BAL Rapid Mat uncoupling mat and a flexible adhesive.

Your choice of grout should be flexible to allow for thermal movement.BAL Superflex Wide Joint Grout is one of the recommended BAL grouts.