UNDERFLOOR HEATING KEEP YOUR COOL David Wilson, UK Technical Services Manager at Building Adhesives Ltd, advises on what
to be aware of when tiling over heated floors, to ensure you don’t get hot under the collar when tasked with such a project.
With their popularity increasing year-on-year, heated floors are fast becoming the norm for tilers to be faced with when starting on a job.
All materials, when subjected to temperature fluctuations, will expand and contract to different degrees. In the case of heated floors, the coefficient of thermal expansion of the background substrate, the type and size of tile chosen, as well as the tile adhesive selected, should not be too dissimilar. If this is not the case, then excessive stresses may be generated within the tiling installation that are sufficient enough to result in either debonding or cracking of tiles and grout.
To counteract any potential for trouble within a tiling installation, adequate planning and preparation is crucial, as is the correct selection of materials and placement of movement joints.
Hot Water Pipe System (Underfloor
Heated Screeds) If tiling onto a Hot Water Pipe system (usually incorporated into a reinforced cement:sand screed), ensure the screed has fully cured. This ranges from one week, for screeds containing BAL Quickset Cement, to a minimum of three weeks for a screed containing OPC.
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Following this period of curing, the screed should be heated slowly at a maximum rate of 5°C per day, up to its maximum operating temperature as recommended by the heating manufacturer. It should be maintained at this level for a further three days, before allowing it to cool to room temperature.
Ensure that the heating system has been turned off, or kept on in cold temperatures, so that the screed is maintained at approximately 15°C before tiling commences.
For anhydrite, hemihydrate or calcium sulphate screeds, extra drying time and screed preparation is required,
www.tomorrowstileandstone.co.uk
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