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Bitumen and Uneven Floors

Discussion in 'Floors, Stairs and Lofts' started by supapee, 26 Feb 2011.

  1. supapee

    supapee

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    Hi All

    I've been sitting here quietly building up sufficient knowledge to tackle the installation of some solid wood flooring to our hall and cloakroom.

    However, I'd like your collective opinions on my situation...

    The house was originally built in October 1964, so just pre-dates the required installation of a DPM as far as I'm aware, and the front of the hall was extended in 1976.

    The hallway floor seems to be two slabs on concrete - the original was covered in parquet flooring, which has been removed to leave a lovely black residue. It's not a 100% covering, and is no more than a couple of mm at it's thickest, so guess it was not used as a DPM? The floor also not flat - maxing out at 6mm low in several areas, and is not level - it runs 15mm out across the width of the hall - a span of 145cm.

    The other slab is approx 12mm higher, now that the parquet has gone, and is also not flat - lows topping out at 4mm and it slopes 15mm up over the 1.1m from the front door to the point at which it joins the original slab. The ceramic tiles in the cloakroom are another 5mm higher still.

    We were steered towards a local flooring contractor, who initially used some kind of damp meter to conclude the the concrete floor was damp. However, this was straight after lifting a floated laminate floor, and there were suggestions that the combination of underlay and laminate might have made the concrete "sweat", so we agreed that he would come back in a weeks time.

    A week on, the readings were "normal" - I don't know what they actually were, and I don't think that he recorded them..

    The contractor suggested using 12mm ply mechanically fixed to the bitumen covered area, sitting a sheet DPM over the entire area and floating the wood on some kind of adhesive underlay over what would be plywood, concrete and ceramic tiles. Quotes are awaited.....

    I've got a number of concerns - the method of raising the bitumen covered sub-floor, the moisture levels that were initially present (especially given the age of our home), the effects of a DPM over a plywood base and the fact that the contractor didn't even bother to check the various levels of the sub-floors or the relative "flatness" of them. He didn't ask in which direction I wanted the boards laying, (they will be running along the length of the hall) and I guess that having a 15mm slope over 1.1m and then a "flat" surface might make installation a bit difficult!! Also - all these measurements are mine, not his!!

    As a bit of an aside, there is a blast of air coming under the wall where the original slab meets the extension!!

    Although we're not putting any really expensive flooring down, I want the sub-floor to be right.

    I'm leaning towards removing what bitumen I can (probably using some kind of grit blaster) and then testing the RH of the two slabs to ensure that no additional DPM is needed, before taking up the tiles in the cloakroom and leveling the whole lot.

    However, that's a bit of work, inconvenience for the better half and a bit of additional cash. Is there a better way??

    Supa
     
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