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Preparation for Thermalite blockwork?

Discussion in 'Plastering and Rendering' started by Rhothgar, 8 Dec 2018.

  1. Rhothgar

    Rhothgar

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    I was chatting with a mate who retired from plastering 20 years ago, he reckons a really weak mix of PVA is required to limit suction.

    Trouble is he didn't say how weak or how many coats? He did say hit it with a 2nd stronger mix but didn't say how strong! Read horror stories on the forum about PVA peeling off! I would like to avoid any plaster ending up on the floor ideally!

    Also, how soon do you put the undercoat on after PVA'ing?

    This is probably a can of worms questions but would you use Dricoat or Hardwall for thermalite.

    I did think of lathing the whole wall with expamet but it's a big area, in a kitchen and I suppose liable to rusting eventually if I don't use stainless steel lath.

    By the way, it definitely Thermalite and I'm not just bandying the term about generically. It's as soft as baby's sh............. and as horrible as. :)
     
    Last edited: 8 Dec 2018
  2. 23vc

    23vc

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    If it was me I’d pva it as it’s going to be a pig of a job, but strictly speaking you’re meant to just soak them.
    I’d use hardwall = high suction backgrounds.
    Doubt there’s any need to wait for pva to dry, it’ll be dry before you’ve finished coating it.
    Thank god for dot and dab...
     
  3. foxhole

    foxhole

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    Mines all covered with insulated plasterboard glued straight to block work and skimmed .
     
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