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Should I break out the concrete slab in my flat? - help!

Discussion in 'Floors, Stairs and Lofts' started by George Hartshorn, 5 Jan 2021.

  1. George Hartshorn

    George Hartshorn

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    I'm at a loss as to what decision I should make. I'm just in the process of buying a new lower ground floor flat in London which is approx 50sqm. Its been unoccupied for a few years and we will be renovating before we move in.

    In the late 80s the wooden floor was ripped out and replaced with a concrete slab. I'm not sure if the concrete slab has an effective damp proof course, and the flat itself has an issue with damp. We have had an independent specialist in who has recommended an injected DPC in the walls, and that we install a membrane under any floor we plan on installing.

    The copper pipes for our central heating run through the concrete slab. I'm terrified that we'll have a leak at some point as it's over 30 years old and have to dig up the slab after we have moved in and laid any flooring on top.

    Now I feel like my choices are as follows... I have a few comments and questions about each potential route. If anyone can advise on them below it would be greatly appreciated.

    Worth noting that I will likely get professionals in to do any concrete work

    1) Do nothing with the slab. Install Oldroyd Xs, followed by UFH, and then engineered hardwood flooring on top

    - This definitely feels like it will be the cheapest and easiest option as it's non-intrusive, however the downside is our flat already has low ceilings, so we'd be loosing about 25mm of height.

    2) Dig up the slab, re-cast with a DPM which I know wont be defective, followed by layer of Insulation, UFH heating system, screed, engineered hardwood flooring

    - Is there any way I can tell if the DPM in the current floor might be effective/defective?
    - How long would it take for a tradesman to dig out the concrete slab and recast?
    - What should I budget for the digging up & recasting of the slab?
    - Would it be possible to lower the concrete slab, therefore giving myself some more height in the flat? The main issue I can see here is having a higher ground level outside which could bridge any DPM, could this be resolved by a french drain or similar outside?

    3) Dig up slab, reinstate hard wood floor

    - Is this possible / has anyone done it in the past?
    - There are air bricks on the outside of the flat which could be reinstated
    - What are the costs of putting in a new hardwood floor over 50sqm?
    - Would we still need to re-cast a concrete slab with a DMP underneath the floor? In which case would it need a DPM?

    Thank in advance
     
    Last edited by a moderator: 5 Jan 2021
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  3. sxturbo

    sxturbo

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    why did they lay concrete slab? its more expensive than replacing wooden floor, did they have a rat problem possibly caused by an old un recorded drain or something?

    the concrete floor should have been laid lower than the existing dpc, then a membrane installed and insulation and then a screed on the top.

    the cheapest option is as per your experts advise, inject a dpc intot he walls and lay a membrane under any flooring.

    regards the copper pipe work, i assume it would have been lagged before being buried in the concrete and should be fine.
     
  4. George Hartshorn

    George Hartshorn

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    Can't say why they did it, our surveyor reckoned it's due to decay / beetle infestation, but in doing so they have bridged the DPC.

    Such a shame as this flat would be perfect for us with the wooden floors
     
  5. sxturbo

    sxturbo

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    you can install hardwood flooring on top of concrete
     
  6. George Hartshorn

    George Hartshorn

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    I should have mentioned - as it's lower ground floor we're already seriously lacking in height. Taking any height off it will make it feel very cramped (and the height in our kitchen area is already under 2m)
     
  7. sxturbo

    sxturbo

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    hard wood flooring is 21mm, and you only need to put a plastic sheet underneath it to stop the damp coming through, though it will be cold.

    as i said the correct and proper way to deal with it is to remove the concrete, lay a cement slap below dpc, membrane and insulate then screed on top, then hardwood flooring of choice.
     
  8. Tigercubrider

    Tigercubrider

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    non expert here
    If it's a ground floor flat does digging up the slab impact on the neighbours? (I don't mean noise)
    if the ceiling is low, is it because the flat was once non habitable and they just bunged in a slab?
     
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