Can I tile over electric underfloor heating mats?
Electric underfloor heating mats can be laid on almost any surface, provided the surface is clean and relatively flat. They are conventionally covered with a flexible tile adhesive or a self-levelling compound, both of which can be tiled directly onto. Whether this will be enough to heat your extension depends primarily on how well insulated it will be. Ideally, you should carry out a heat-loss calculation for the new extension, from which you would be able to calculate the heating demand. If, for instance, you determine that it will require 3kW to keep the extension warm on a cold night, then you can calculate how much electric underfloor heating to fit. For instance, one of the leading manufacturers, Devi (devi.co.uk), produces two suitable heating mats — one rated at 100W/m², the other at 150W/m². However you do it, you would be well advised to fit a good thickness (say at least 100mm) of underfloor insulation. This will ensure that virtually all the heat from the electric mats stay
