Dismiss Notice

This website uses cookies

We use cookies to personalise content and ads, to provide social media features and to analyse our traffic.
You consent to our cookies if you continue to use this website.
Dismiss Notice

Thanks for visiting us!

Tilers Forum is a free community for Tilers, Tiling Suppliers, Tiling Manufacturers and anyone who likes tiling!
If you find anything useful here please consider registering and getting involved with our community.

Click here to join!

Question Underfloor heating. On or off when tiling?

Discussion in 'Underfloor Heating Forum' started by TLL Tiling, Dec 27, 2014.

  1. TLL Tiling

    TLL Tiling Guest



    The Tile Association state: "The heating system should be commissioned following the manufacturer’s
    instructions before and after tiling. It is important to ensure that the underfloor heating system is turned off and cooled down to ambient temperature during the tile adhesive and grouting curing periods.


    What some adhesive manufacturers state in their fixing instructions:

    BAL (owned by Ardex) - "After drying, the screed should be heated gradually. The temperature should be raised, increased by no more than 5º C each day, to a temperature of 25º C and maintained at that level for three days before being allowed to cool naturally to room temperature. The heating system must have been turned off or, in cold weather, turned down to below 15º C. Tiling can then begin."


    - Weber (owned by Saint-Gobain) - "The heating system should be turned on and raised by a maximum of 5°C/day until the maximum recommended operating temperature is achieved. This temperature should be maintained for 3 days and then the system turned off and the screed allowed to cool to 15°C before tiling commences. Cement-based adhesives (and grouts) set hydraulically i.e. water is involved in the hardening reaction. If the adhesive is allowed to dry out before it has properly hardened it will tend to be weak and crumbly. It is important that the heating system is off when tiles are fixed and remains off until the adhesive and grout have fully cured."


    - Larsen - "You must ensure that the heating is turned off at least 48 hours before any tiling work is carried out"


    - Norcross: "The screed must be at least 3 weeks old to enable movement caused by drying shrinkage to have taken place. After 3 weeks, the heating should be switched on to heat gradually to its intended
    temperature, a rate of 5oC every 24 hours is recommended. After 3 days allow the heating to cool
    to room temperature. The heating should either be switched off or, in cold weather, turned down to below 15C before tile fixing commences.

    http://www.coloursupplies.com/How To Tile to Screed Floors with Underfloor Heating.pdf

    - Tilemaster
    : "Underfloor Heating Systems: When tiling onto existing underfloor heating you must
    switch the heating off 48 hours prior to tiling
    to allow the substrate to cool sufficiently.
    Underfloor Heated Screeds should be commissioned prior to tiling. Turn on the heating system at a low temperature and heat the screed gradually by no more than 5°C per day until a maximum temperature of 25°C is achieved. Maintain this temperature for 3 days and then switch the heating off 48 hours prior to tiling to allow the substrate to cool sufficiently. Alternatively in cold conditions, reduce the temperature of the screed to below 15°C prior to tiling".

    http://www.tiletown.co.uk/published/39/resources/documents/Standard Set Setaflex_TDS.pdf

    - EcoScreed: "Underfloor Heating: Ensure the screed is sufficiently dry and down to a 75% relative humidity. The under-floor heating system should be commissioned before tiling commences. Gradually heat the screed, starting at the minimum temperature and increase the temperature by no more than 5C per day. Heat the screed to a maximum of 25C and maintain this temperature for 3 days or until the screed has reached 75% RH before allowing the screed to cool down to room temperature. Turn off the heating 24 hours prior to tiling, or in cold conditions, the screed can be reduced to below 15C."


    I personally have always tiled with the UFH off.

    But there is no British Standard (that I can find) governing how to tile onto heated floors (electric or wet in screed), or that states that it must be off, or can be on, and if on, what procedure and temperature should be followed.

    Therefore, over to you!

    I will not post a single response to this thread, even if I vehemently disagree with something someone posts (a forum first, and will require a lot of willpower on my part! :speechless: :laugh:).

    YOU decide if, how and why UFH should be on or off when YOU tile onto it.
  3. EssexTiler

    EssexTiler Well-Known Member

    Always been off for me, except the one I am on at the moment.
    The plumber and builder want a little bit of heat in the room over the Xmas shut down so has turned the wet ufh on.
    I was working or did a site visit to check temp was not above the 15C, I bought one of these.
  4. garythetiler

    garythetiler Well-Known Member

    I have seen so much conflicting information over the years when working with under floor heating , I think the recommendations for commissioning under tile heating prior to tiling is more to do with allowing the substrate to crack and settle I can't see why working with a floor that has been commissioned and the heating is on but kept at a constant low temperature eg 18 degrees c which is only room temperature would adversely,effect the setting of the adhesive
  5. EssexTiler

    EssexTiler Well-Known Member

    Totally agree Gary.
    Saying that though if an uncoupling membrane is fixed after 2 or 3 days of the screed being laid this will dramatically improve the quality of the finished screed. Not recommended for heated screeds.
    Screeds should be covered with plastic when laid to help the curing process and to help stop screed curl. I have never seen this done in all my time as a tiler.
  6. EssexTiler

    EssexTiler Well-Known Member

    Been reading up on the net.
    Found this on maximum 'Comfortable' under foot floor temperature.

    Anyone tell me what is meant by 'Comfortable ' ?
    Is there a British Standard for 'Uncomfortable' under foot temperature?

    "British & European standards

    Several standards cover the different areas of underfloor heating, and are detailed below:
    •Wet systems fall under the British standard BS.EN 1264, Parts 1 to 4. Part 2 of the legislation states that the maximum comfortable temperature underfoot is 29°C; while part 4 specifies the allowance in wet rooms of a maximum floor temperature of 33°C, and 35°C for a one metre perimeter zone. The standard also sets out a limit of 1.5 TOGs for any floor coverings.
    •Most types of flooring are comfortable within this temperature range; basic vinyl flooring and lino can withstand a surface temperature of 27°C, while heavy duty plastic sheeting can tolerate a 29°C surface temperature.
    •Wood floors are not normally designed to cope with temperatures in excess of 27°C, but carpet and carpet tiles are able to withstand any temperatures within the range."
    garythetiler likes this.
  7. EssexTiler

    EssexTiler Well-Known Member

    Sent Weber an email this morning, got a reply straight away. Good service. :)

    Question was
    "Could you also tell me the max air and substrate temp which you would recommend for your adhesives? "
    "Hi Julian,
    Yes the maximum would be approximately 30°C, as the product would dry too quickly at higher temperatures, particularly the rapid setting product. Once cured, after approximately 7-10 days the product can cope with higher temperatures up to 100°C, so if fine for under floor heating installations and fire places etc"

    This throws up more question about wet ufh floor temp when tiling... :)
  8. EssexTiler

    EssexTiler Well-Known Member

    BAL response : Tiles will not be fixed if the temperature of the background/base is in excess of 65°C.

    If both BAL and Weber adhesives (and probably most if not all other manufacturers) are happy for you to fix on substrates with higher temperatures.
    Can anyone tell me the logic behind why wet ufh needs to be, or it is recommended to be off or at a very low temperature when fixing tiles?