Prep Advice required.

Discussion in 'Subfloor Preparation' started by rikaka85, Mar 26, 2021.

  1. rikaka85

    rikaka85 Member

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    Hello everyone,

    I've been reading through the forum and have picked up bits and pieces of great advice, some of you are very knowledgeable and must be great tradesman.

    I am looking for some advice specific to my project if possible.

    We are getting to the stage in our extension where the flooring is becoming my attention.

    The current dining room has 28mm floorboards over joists. The new extension has a concrete floor.

    We are looking at laying engineering wooden floor, with electric underfloor heating for comfort rather than primary heating source.

    What's the best way to prep the two different subfloors? I have around 30mm build up to achieve to tie into an existing tiled hallway off the dining room.

    The current front running for flooring is 20mm thick but this can change if more room is required for proper sub base prep.

    The floors tie in ok, definitely not the worst you'd have seen.

    I'll get a couple of pics up today.

    Thanks for any advice
     
  2. rikaka85

    rikaka85 Member

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    Pics attached [​IMG][​IMG][​IMG][​IMG]

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  3. merit

    merit Well-Known Member

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    First thing you need to do is make sure it’s all dry enough. Moisture test the subfloors.

    Are you using the heating over both wood and screed bases?


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  4. merit

    merit Well-Known Member

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    There are hundreds of electric ufh manufacturers and they all seem to have a different way of doing things. I would ask them for the required prep. Usually you will need to put down some type of insulation board first to force the heat upwards. Then the matting and then either a 10mm coat of levelling compound or some type of overlay board


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  5. rikaka85

    rikaka85 Member

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    Hi, yes over both bases.

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  6. rikaka85

    rikaka85 Member

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    The ones I am looking at site directly underneath the floor with no screed. They recommended an XPS type board underneath the mat, both the subfloors are insulated so I am not sure they would be required? Also I have read that XPS boards are not great as an underlay?

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  7. mjfl

    mjfl Well-Known Member

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    Is that a Gypsum floor in the extension?
     
  8. rikaka85

    rikaka85 Member

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    No, just a standard insulated concrete floor. The patch between the concrete and timber is where a ground beam was installed to support the steelwork, the patching is concrete but done at a different time to the slab.

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  9. AngryAndy

    AngryAndy Well-Known Member

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    14 or 15mm flooring will be better over UFH. Less thermal resistance.
     
  10. rikaka85

    rikaka85 Member

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    Thanks, yes that makes sense and changing isn't an issue. Anyone get any advice on best practice for preping the 2 substrates?

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