Rendering smooth lightweight blocks

Discussion in 'Builders' Talk' started by 14th edition, Oct 12, 2017.

  1. 14th edition

    14th edition Well-Known Member

    We are building and extension and its lightweight ytong's on both leaves. Although they are not really smooth there is no scratching was you get on say Celcons or Thermalites. I am rendering it myself, done lots in the past but not sure whats the best preparation fro this block.
    I have a few choices as the surface is not rough enough and the bricky didn't rake the joints. Mesh, [no thanks], use a proprietary prep mix or scratch it up. I think the last one...? I was going to XXX lightly with and angle grinder or would there be a better solution. Using 4 :1 first coat and 6:1 second with waterproofer.
  2. dobbie

    dobbie Well-Known Member

    You could try scudding the walls to give the render a key.
  3. KIAB

    KIAB Well-Known Member

  4. 14th edition

    14th edition Well-Known Member

    Thanks for replies, going to rough/scratch up the surface!
  5. 14th edition

    14th edition Well-Known Member

    Update.... Tried the Weber rend aid and its the dogs danglies. Quite expensive at 20/25kg but it covers around 7m2 on smooth blocks and sticks like you know what to a blanket. 2-3 day wait before next coat goes on but didn't seem to have much suction when I put scratch coat on top.
    KIAB likes this.

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