Screeding over block and beam

Discussion in 'Subfloor Preparation' started by Northers, Aug 15, 2019 at 7:03 PM.

  1. Northers

    Northers Member

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    Hi all
    I’ve got a job with a badly warped 18mm chipboard floor over polythene and 25mm polystyrene laid directly over block and beam.
    I’m thinking of replacing it with 4:1 sand cement screed.
    Does this sound sensible? Any other solutions? It’s in a kitchen that gets quite a lot of moisture thrown around so don’t really want to go down the batten and ply route and marine ply is cost prohibitive.
    Any advice gratefully received
    Thanks
    Andy
     
  2. Neilydun

    Neilydun Well-Known Member

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    Any height restrictions ?
    Whats the situation, domestic ?
    Would you not insulate first ?
    What thickness screed are you thinking ?
     
  3. Northers

    Northers Member

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    It’s a domestic and I was thinking of 40mm screed straight on top of blocks maintaining current floor height could go thicker but can’t go more than 70mm total above block surface.
     
  4. Neilydun

    Neilydun Well-Known Member

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    I would want some insulation in there myself. How big is the area ?
     
  5. Northers

    Northers Member

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    It’s 3m x 5m
    I’m rethinking my view on 40mm battens, celotex between and ply on top....
    what ply do you think would be ok?
    Maybe go over with 6mm marine?
     
  6. merit

    merit Well-Known Member

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    Defo put some insulation in if you can then screed


    Sent from my iPhone using Tapatalk
     
  7. Neilydun

    Neilydun Well-Known Member

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    Agree with Merit, insulation & screed is the best option.
     
  8. Northers

    Northers Member

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    Thanks guys
    So given I’ve got 70mm to play with what combination of insulation thickness to screed thickness would you recommend?
    25 & 45?
    Ta!
    Andy
     
  9. Neilydun

    Neilydun Well-Known Member

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    If thats the max depth then, yes I would say so. Fibre added to mix will help with strength in the screed.
     
  10. pf flooring

    pf flooring Well-Known Member

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    6mm no good as that is a top coat at that thickness, I'd say 24mm minimum you may get away with 18mm but thicker the better to get a stable solid floor
     
  11. Northers

    Northers Member

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    I’m going to go with 40mm Celotex 18mm ply overboarded with Sp101 at 6mm, anyone have experience of using Sprucefloor panels?
    They do a 22mm T&G ply that looks interesting. Google Wisaplywood Sprucefloor pdf
     

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