advice on concrete floor prep

Discussion in 'Subfloor Preparation' started by choffer74, May 23, 2021.

  1. choffer74

    choffer74 Member

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    hi all,

    keen DIY'er here. Just about to start laying down some solid wood parquet in the lounge and kitchen. The house was built in the mid 90's.

    I've taken up the existing (horrible!) laminate floor to inspect the concrete. Its really level and seems in pretty good condition. But there are a couple of cracks, and would also like some advice on whether I need to put down some DPM.

    1) Cracks - I've attached pictures of the 2 cracks. One is in the doorway between the kitchen/lounge - approx 3mm at its widest. The other is in the lounge entrance - maybe 1mm wide. Will I need to fill these in before laying the flooring? B&Q have some cheap concrete repair, but worried that I need a specific type that wont react with DPM or the wood.

    2) DPM - I've got a basic moisture meter and the readings range from 0.2% - 0.6%. Manufacturers guidelines indicate you only need to use a DPM if readings are > 2%. Do I still need to lay down a liquid DPM? If I do need to lay it, would I need to prime it after? (or are there products out there that are DPM and primers?)

    Thanks in advance for any advice
    G
     

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  2. tarkett85

    tarkett85 Well-Known Member

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    You always need either a surface dpm or moisture suppressant for bonding solid wood, you need to take correct Rh% readings with a hygrometer to discern which to use, other than that Ardex A46 to repair the cracks, K301, DPM 1 C or MVS 95 (depending on Rh reading), P4 on DPM 1 C or don’t prime MVS then K11 before bonding the wood down as a general rule without seeing it.


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  3. merit

    merit Well-Known Member

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    Murexin MSX-3 silane dpm then bond direct to that. Only need a primer if it’s been left more than 2 days.
    Or bona have a silane dpm and adhesive system. 90s built shouldn’t have moisture issues unless you’ve had some work done like taking out walls.
    Make sure you don’t have any shallow central heating pipes in the screed or your floor will shrink


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  4. choffer74

    choffer74 Member

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    thanks for the advice guys. All the pipework is in the walls, nothing in the floor. We've removed a stud wall between the dinning room/kitchen, but that's it for 'structural' work.

    If the Bona quantum is suitable as an all-in-one DPM and adhesive - that's a massive difference in terms of cost and time. (We've got kids and a dog that we have to work around. So having the lounge and kitchen out of action for a number of days to DPM/screed/prime etc is not really an option). It almost seems too good to be true. Anything I should be aware of before I go down this route???

    And one more thing I started taking up the last few tiles in the kitchen and there's some old lino underneath the laminate. - I've attached photo. Do I need to remove the adhesive that's still on the concrete? and if so whats the easiest method.

    Having done a lot of research over the last few days, I hadn't realised how much technical knowledge is required to ensure a good final product that is going to last. Take my hat off to you pro's!

    And once again, really appreciate the time you take to answer questions from us DIY'ers!
     

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  5. dazlight

    dazlight Super Moderator

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    Get yourself a decent blade scraper mate to get that adhesive up
     
  6. merit

    merit Well-Known Member

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    Yeah you need to remove all the old adhesive and if you use the bona quantum you need a special trowel and need to make sure the subfloor is completely covered with the adhesive
    I’ve not used it yet so not sure how practical it is but it sounds like a great idea


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