Floating screed, cracks and movement

Discussion in 'Subfloor Preparation' started by JamesGibs0, Sep 22, 2020.

  1. JamesGibs0

    JamesGibs0 Member

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    We have had an extension and wet UFH installed across the whole ground floor (new and old).

    UFH in the new extension is clipped on top of celotex. UFH in the existing is embedded in an insulation board. - about 45m2 in total

    We've had a floating screed installed (Longfloor CT-25/F5) and 3 cracks have appeared in areas you would expect to commonly see a hairline crack (doorway and entrance to hallway).

    2 of the cracks are 1mm wide, the 3rd is about 3mm wide. ALL of these cracks have movement on one side of the crack of about 2 - 3mm.

    We're going to be laying a smoothing compound (Mapei latexplan trade) then Karndean LVT.

    Question. WHAT DO I DO ABOUT THESE CRACKS? :(

    The screed company told me it wouldn't be an issue, and he seemed convincing while on the phone, but after thinking about it I'm really not so sure. I don't want the cracks to ruin the LVT floor or get worse over time.

    Thanks in advanced.

    p.s. family of 4 living with in-laws, desperate to get this house finished so we can live again in "happiness". please help
     
  2. Distinctive Adam

    Distinctive Adam Well-Known Member

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    How deep is the screed ?
     
  3. JamesGibs0

    JamesGibs0 Member

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    New has a depth of 70-80 depth easily. Existing has a depth of about 30.
     
  4. merit

    merit Well-Known Member

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    And it’s got movement?


    Sent from my iPhone using Tapatalk
     
  5. JamesGibs0

    JamesGibs0 Member

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    Yep, when you step on one side it gives by a few mm
     
  6. Rugmunching

    Rugmunching Well-Known Member

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    Needs doing again!
     
  7. JamesGibs0

    JamesGibs0 Member

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    Thanks for your opinion.

    What's your reason for it having to be replaced? What's failed?
    Is it not repairable?
     
  8. Rugmunching

    Rugmunching Well-Known Member

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    If the slab is loose then whatever you put over it will be loose and that goes for the screed you put over it.
     
  9. Rugmunching

    Rugmunching Well-Known Member

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    You could try a crack repair with the right system but if its moving a few mm then I wouldnt want to risk it myself.
     
  10. merit

    merit Well-Known Member

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    Sounds very dodgey. Not sure a 2mm vinyl tile is going to last long over that type of subfloor. Maybe look at using floorfix or jumpax system do your not bonding to the slab.


    Sent from my iPhone using Tapatalk
     
  11. Spacey

    Spacey Super Moderator Staff Member

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    I doubt it'll be getting redone

    One option would be Resin crack repair and metal switches then prime and lay reinforcement mesh over the whole floor and screed with uzin 110

    Its an expensive prep but I've used the mesh and 110 over pretty much rubble and it held together
     
  12. JamesGibs0

    JamesGibs0 Member

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    Thanks all for you advice, really appreciated

    I'm planning on attempting a resin crack repair (ardex or Uzin with the metal clips) and then the Uzin mesh over the top.

    Sourcing Uzin product seems difficult, any recommendations at all? Hoping for next day delivery
     
  13. Spacey

    Spacey Super Moderator Staff Member

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    What wholesalers do you normally use ?
     
  14. Paul webb

    Paul webb Well-Known Member

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    IMG-20180910-WA0000.jpg i came across a similar problem a couple of years ago, the manufacturer managed to fix it with this
     
  15. Paul webb

    Paul webb Well-Known Member

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    Just doing localised repairs may not solve the long term problem, you may just have more cracks appear elsewhere
     
  16. Paul webb

    Paul webb Well-Known Member

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    Sorry, missed the mesh part of your last post
     

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