Cracked 20mm Grano screed

Discussion in 'Subfloor Preparation' started by DM Flooring, Apr 1, 2014.

  1. DM Flooring

    DM Flooring Well-Known Member

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    Evening chaps. I've been to look at a floor today to measure up for Karndean. The floor has a concrete base then a 20mm/25mm grano screed. The grano screed has cracked terribly and theres movement in a couple of places. Any thoughts on this. I have mine but I want to see what you guys think.
    The customer will be viewing this so be good and the builder who did the grano screed is a very good friend of his. I was told he's done quite a few before of the screeds and he can't understand what's uploadfromtaptalk1396372881916.jpg uploadfromtaptalk1396372912161.jpg uploadfromtaptalk1396372932483.jpg uploadfromtaptalk1396372962192.jpg happened to this one.
    All decent input will be appreciated.
     
  2. Spacey

    Spacey Super Moderator Staff Member

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    Could be not bonded or dried to quick or the compression strength it to high or not mixed correctly or all of it ?
     
    Last edited: Apr 1, 2014
  3. DM Flooring

    DM Flooring Well-Known Member

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    From what was said I think the concrete underneath sucked all the moisture out. He said the builder unibonded it but to my reckoning it was too weak a mixture.
     
  4. merit

    merit Well-Known Member

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    Is it hollow? If its blown its gotta all come up
     
  5. DM Flooring

    DM Flooring Well-Known Member

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    Yep its hollow.
     
  6. Spacey

    Spacey Super Moderator Staff Member

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  7. DM Flooring

    DM Flooring Well-Known Member

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  8. DM Flooring

    DM Flooring Well-Known Member

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    Matt what do you think? Any feedback mate?
     
  9. Rugmunching

    Rugmunching Well-Known Member

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    Weak mix by far off!
     
  10. Spacey

    Spacey Super Moderator Staff Member

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  11. Trimmer

    Trimmer Well-Known Member

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    Priming problem, unibond isn't the best for flooring.
     
  12. pf flooring

    pf flooring Well-Known Member

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    Not used proper primer and used to much water in his mix id of said, seen a fitter who used to work for the same firm I do and he used to water his bag and bottle so much it went white like that.
     
  13. dazlight

    dazlight Super Moderator

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    Maybe go with a coat of stopgap 600 base then a top coat of stopgap 1200 pro
     
  14. DM Flooring

    DM Flooring Well-Known Member

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    Has anyone got a ratio equation I can use. I want to level 26sqms at 20mm. First mix I want to put granno to bulk out then next screed to make smooth and level.
    How much granno to use on first mix per bag.
    Only granno'd smaller areas before and that was yonks ago.
     
  15. pf flooring

    pf flooring Well-Known Member

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    mapei reonovation has it already in with it and is actually quite a good screed or k15 by ardex.
     
  16. dazlight

    dazlight Super Moderator

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    Renovation has fibres in it mate.
    I do half a bag granno to one unit screed. Not sure on the size of the granno bag though. It's the one I use from Jedens.
     
  17. DM Flooring

    DM Flooring Well-Known Member

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    Is that a builder's merchants pal?
     
  18. merit

    merit Well-Known Member

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    So your gonna need 32 bags of screed and 16 bags of chips then 6 bags of screed to finish? That sound about right?
     
  19. DM Flooring

    DM Flooring Well-Known Member

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    Yeah thats what I figured. Gonna be expensive. Hes been quoted just over £1000 for pump screed. Working on say £25 per bag including profit then labour its going to be cheaper.
     
  20. dazlight

    dazlight Super Moderator

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    No its a flooring place I use. West derby rd
     

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