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Putting in a solid concrete floor

Discussion in 'Building' started by Deleted member 286438, 14 Apr 2021.

  1. I've got a wooden floor with joists and am replacing it with concrete
    What is the correct materials to use and the order of materials that you need as I've been told different things from different people?
    It's dug out and ready to be started
    Thank you
     
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  3. sxturbo

    sxturbo

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    Hardcore, concrete, DPM, insulation, screed
     
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  4. How deep does the "hardcore" need to be?
    Should the "hardcore" be MOT and I thought you were supposed to have insulation before the concrete slab.
    Does the concrete get poured straight onto the DPM?
    Where do you input the sand?
     
    Last edited by a moderator: 14 Apr 2021
  5. sxturbo

    sxturbo

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    Mot type 1, compacted. 75-100mm

    If you want to pour concrete on top of DPM then you will want to put sand blinding ontop the mot type 1 , 50mm

    Concrete 100mm,

    Insulation

    Screed 50mm.


    Personally I wouldn't bother with the blinding sand, and just pour the concrete, then put the DPM under the insulation, it's saves imo an unecessary expense of sand.
     
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  6. 23vc

    23vc

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    Or do away with the screed and concrete it to finished floor level and finish with a float. Just another option and slightly easier to DIY than screed
     
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  7. sxturbo

    sxturbo

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    Would you put the insulation under the concrete then?

    To the op, are you going to install under floor heating?
     
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  8. 23vc

    23vc

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    I’ve done that before yeah. I’ve also screeded on concrete on insulation but never screeded on insulation. But then UFH wasn’t involved. And come to think of it you could also put the insulation on top of concrete and floating floor sheets of whatever on top, if you went the no screed route. Loads of options and have probably totally confused the OP but didn’t mean to
     
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  9. Ian H

    Ian H

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  11. ^woody^

    ^woody^

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    Minimum 100mm hardcore
    25mm blinding sand
    DPM
    80mm PIR insulation or 150 EPS
    100mm concrete
    Minimum 50mm screed
    1 building regs application

    Block up vents
    Ventilation to existing timber floors?
    Non radon area or other ground contaminants?

    Floor levels of timber floors are normally higher than the DPC in the walls
     
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  12. Does hardcore have to be MOT?
    Would I be right in thinking that 80mm PIR is what the brand known as KingSpan is? Is EPS (Expanded Polystyrene insulation) as good and is there much of a price difference?
    So I assume that because you need twice as much of the EPS then it's twice is good as KingSpan? Correct?
    Is 50mm screed plenty strong enough if it's a sand and cement screed? Is 100mm concrete also a minimum?
     
  13. I'm looking for a traditional sand and cement screed
     
  14. noseall

    noseall

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    Easier? :eek:
     
  15. 23vc

    23vc

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    Yep. Give me careful tamping then getting the odd blister sliding around troweling it out later in the day on a piece of celotex, than a screed job especially if it’s a big area. Then again I’ve only ever done screed a handful of times and mixed it myself and it was flippin hard work. If I was doing these every day then may have a different view ... and there’s always SLC ;)
     
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  16. SpecialK

    SpecialK

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    Kingspan (or a cheaper brand! ie quinn or ecotherm) is better than EPS. That's why you would need 150mm of EPS and only 75mm of PIR type...
    EPS is much cheaper but you will need to dig down deeper...

    Why are you converting to a concrete floor?
     
    Last edited by a moderator: 16 Apr 2021
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