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Best LVT floor prep when half concrete half chipboard

Discussion in 'Subfloor Preparation' started by Catflap, Nov 23, 2019.

  1. Catflap

    Catflap Member

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    Quick question.

    we have a room with the floor that is half concrete and half chipboard (previously extended into the garage).

    looking to have Karndean laid and different fitters are approaching it in different ways. One would ply the chipboard and scree / latex the concrete the other said they wouldn’t do that but use a flexible scree across the whole thing as over time they think a line would appear where the ply and scree meets and that would become visible in the LVT.

    Is there a correct or best way in this situation?

    TIA
     
    Catflap, Nov 23, 2019
    #1
  2. Spacey

    Spacey Super Moderator Staff Member

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    Amateurs

    The ply must be spanned over the edge concrete then glued down Then screed up to the level of the ply
    A flex screed may not be needed if everything is flat Feather finish all seams is normally sufficient
     
    Spacey, Nov 23, 2019
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  3. merit

    merit Well-Known Member

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    Or jumpax over the lot that way it doesn’t matter about the join between the rooms


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    merit, Nov 23, 2019
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  4. Spacey

    Spacey Super Moderator Staff Member

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    Jumpax should always be a last resort and avoided in kitchens and bathrooms
     
    Spacey, Nov 23, 2019
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  5. merit

    merit Well-Known Member

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    No way, it’s treated and gives you a perfect floor. Plus your not bonding to the subfloor.


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    merit, Nov 23, 2019
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  6. merit

    merit Well-Known Member

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    Personally I think LVT should be installed using some sort of decoupling mat like all decent tilers do now.


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    merit, Nov 23, 2019
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  7. Spacey

    Spacey Super Moderator Staff Member

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    It sucks up water like a sponge if it gets wet
     
    Spacey, Nov 23, 2019
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  8. merit

    merit Well-Known Member

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    Don’t put it round a swimming pool then. Water based screed also fails when it gets wet


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    merit, Nov 23, 2019
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  9. Neilydun

    Neilydun Well-Known Member

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    You two should get a room
     
    Neilydun, Nov 23, 2019
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  10. Rugmunching

    Rugmunching Well-Known Member

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    Haha
     
    Rugmunching, Nov 23, 2019
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  11. merit

    merit Well-Known Member

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    Lol


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    merit, Nov 23, 2019
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  12. Catflap

    Catflap Member

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    So flexible screed directly over everything is not a good plan then? Or it’s ok but might give issues later?

    these are quotes from two established Karndean retailers (one an Inspire dealer). One quote had a bit of info on what they are using

    “install P131 neoprene flooring primer and cover with StopGap 1200 professional, two-part, moisture resistant, latex smoothing underlayment 3-4mm thick“
    No mention of the ply on the quote though we discussed it during the visit and that was what they said they would be doing.

    the other quote just mentions Karndean accredited prep materials.
     
    Catflap, Nov 23, 2019
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  13. Spacey

    Spacey Super Moderator Staff Member

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    What is an inspire dealer :confused:

    A flex screed over the lot is fine but if the ply isn't spanned over the edge of the concrete the screed and possibly the Karndean will crack at the transition

    It fries my brain when I think about the lack of knowledge and common sense these established retailers have
     
    Spacey, Nov 23, 2019
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  14. tarkett85

    tarkett85 Well-Known Member

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    1200 isn’t a flexible screed, personally I would check for moisture in the concrete side, minimum 6mm ply on the chipboard and fibre reinforced over the lot.


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    tarkett85, Nov 23, 2019
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  15. Spacey

    Spacey Super Moderator Staff Member

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    Water based screeds aren't flexible either Fibres just hold them together when they do crack I think it's crazy
    Fibers can be added to any compound
    I think a soft latex with fibres is the way to go when going over ply
    I tend to use Tile master superflow 30 unless it's a large area as it dries super quick Or on decent sizes I use uzin 630 primer then 196
     
    Spacey, Nov 23, 2019
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  16. tarkett85

    tarkett85 Well-Known Member

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    I agree but when people are penny pinching to get the cheaper quote FA20 will do the job better than a latex without fibres.


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    tarkett85, Nov 23, 2019
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  17. Catflap

    Catflap Member

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    The quote that wasn’t using Stopgap was just using flexible (not sure what brand) over both the concrete and the chipboard.

    the stop gap quote I believe are plying the chipboard and the stop gap just on the concrete up to the same level.
     
    Catflap, Nov 23, 2019
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  18. Catflap

    Catflap Member

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    Think an inspire dealer is one who’s paid a load of money to get a big flash Karndean showroom, there are just a handle full of them at the moment. Still a nice place to see Karndean if you can’t get to Evesham, and they give out full size samples!
     
    Catflap, Nov 23, 2019
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  19. Scf

    Scf Well-Known Member

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    I used some tile master pro flow this week, found it brilliant. Flows great, nice finish. Is superflow 30 just the the rapid version of that spacey?
     
    Scf, Nov 23, 2019
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  20. Spacey

    Spacey Super Moderator Staff Member

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    Not really Its a Rapid drying fibre reinforced low compression moisture tolerant latex mix and sticks like s#!¥¥ to a blanket and can be laid upto 15mm thick

    It's great for UFH matts
     
    Spacey, Nov 24, 2019
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