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Internal Rendering mix

Discussion in 'Plastering and Rendering' started by alexbetts, 2 Jan 2009.

  1. alexbetts

    alexbetts

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    Can anyone tell me what a standard render mix is using

    hydrated lime, Cemnet, sand
     
  2. roughcaster

    roughcaster

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    Standard render mix:
    4 plastering sand - 1 cement -1 lime = scratch coat.
    5 plastering sand - 1 cement -1 lime = top coat.

    Use a plasticiser/waterproofer in the batch (mix). This will help to aerate the mix, make it easier to use/spread, and the w/proofer will reduce the suction when you come to the top coat. Always "measure" any admix correctly, especially waterproofer!! ....... Lime in a batch is optional, but it allows flexibility in the finished render coats, and reduces the risk of cracking..... I prefer lime in a mix.

    Roughcaster.
     
  3. diydad888

    diydad888

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    Hi, down here in Edinburgh nearly ready to render/harl my single storey block block extension, can you tell me the best procedure and mix, is it 5 sand 1 cement 1 lime? PVA applied to blockwork?


    Regards
     
  4. Ker-plunk

    Ker-plunk

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    No pva! dampen down the blockwork and follow roughcasters advice on above post.
     
  5. northernwarrior

    northernwarrior

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    I personally would not use lime in a scratch coat , as it can affect the performance of some water proofing additives, but that's my personal opinion
    but the volumes that roughcaster has suggested are ok, but then again i would use a 6:1:1 sand/cement/lime mix in my top coat and no additives, nothing wrong with casters suggestion, this is just my preference
     
  6. diydad888

    diydad888

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    My builder guys have fitted wood to support the verge tiles and it is exposed on the external block work, the wood is 150X50 and is where the verge meets the eaves so is triangle shaped, It is too low down to be covered by verge plastics etc.
    I will try get them to remove as I want only block/brick on external walls, I wish I had noticed this earlier !!
    Is it ok to harl/render onto this ? will it stay on over the seasons? or will the winters swell the wood too much ?


    Thanks
     
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