Help joining extension floor to existing

Discussion in 'Builders' Talk' started by apritcha, Jul 8, 2019.

  1. apritcha

    apritcha Member

    Hopefully someone can offer me advice, I've tried searching and haven't been able to find what I'm looking for so thought I'd ask...

    How do you join a new extension floor to the existing room floor? I have three openings where the new floor needs to join the existing floor and I would like to know whether to remove bricks and screed through the gap (presumably blocking the cavity at the ends of the gap ) or should the cavity be maintained? I want to make sure I create a stable surface as I don't want tiles to crack due to lack of support.

    The external doors I'm planning or removing the inner block work and screeding up to the doors (low cill)

    We're thinking of having free-flowing screed installed and are wanting to keep the existing laminate flooring, any advice if the liquid is likely to cause an issue with the existing flooring? We've previously had a flood and are all too aware how laminate flooring behaves once water gets underneath.

    Cheers in advance,

  2. jonathanc

    jonathanc Screwfix Select

    first of all check your existing floor is perfectly level, if not then forget the freeflowing screed as it will not level up with the existing floor.

    As to joining - take bricks down to the bottom of the insulation later and run your insulation (which I presume is celotex type) into the opening, screed over insulation level with existing floor
    apritcha likes this.
  3. apritcha

    apritcha Member

    Thanks, that's what I thought. I assume DPM goes under the insulation and up between the two floors, hopfuly meeting up with DPM in the existing floor if I can identify one? The house is late 40s and I'm not sure if has much of a DPM, the floors certainly behave differently between the seasons.
  4. jonathanc

    jonathanc Screwfix Select

    or over insulation if you prefer but yes lap it over the existing floor to prevent any bridging and bring it over the DPC in new walls.

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