Apply floor screed to underfloor heating

There are a number of things to consider when applying an underfloor heating screed, but it’s not as complicated as you might think.

Step-by-step guide

  1. Before applying your screed, the surface needs to be dry and free from contamination and 
    other impurities. All dust and debris should be vacuumed from the surface. Some surfaces may contain small holes or feature other irregularities, such as prefabricated elements and differences in height, so be sure to pre-level it before installation of the screed.

    Check that all heating pipes are firmly clipped down and make sure there are stress relief joints in place around all walls, pillars and other uprights.

  2. Working backwards from the wall furthest away, pump the screed directly onto the floor and heating pipes.

    weberfloor fibre 4310 and weberfloor fibre rapid 4320 can be applied to depths from 5-50mm dependent on the substrate, and the underfloor heating pipes will need to be covered with a minimum thickness of 15mm floor screed.

    If the thickness of the floor needs to be greater, weberfloor base rapid 4360 can be applied from 20-80mm –again, this dependant on the substrate. This will need to fully cover the pipes with at least 25mm of screed from the top of the pipes.

    Once fully pumped, finish the surface with a wobbling tool.

  3. Allow an average drying time of 2-4 hours before any foot traffic can be permitted on the floor screed. As a general rule the underfloor heating shouldn’t be switched on for at least 14 days after application. After this time, it should be turned on to a maximum of 15°C, and then gradually turn it up by no more than 5°C each day to reach desired temperature. This is to avoid thermal shock to the screed.

    If the final floor covering is going to be PVC or linoleum, a finishing layer of weberfloor smooth 4150 or weberfloor smooth rapid 4160 is required prior to application of the floor covering.

    If the plan is to tile over the floor, read our guide on tiling with underfloor heating.

Please note:

  • Small hairline cracks may occur due to the building shape or the substrate. These are purely visual flaws and have no influence on the integrity of the floor screed.
  • Pure Portland cement-based screeds or concrete are not suitable to use for this process, due to the aluminium reacting (vaporising) with the high pH of the humid concrete.

Contact us

If you have any questions about laying a floor screed on underfloor heating, or need more clarification about the process, please contact our technical team:

Available Monday to Friday, 8:30am until 5.00pm.

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