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What's best to use to fill these external cracks?

Discussion in 'Plastering and Rendering' started by bertles01, 4 Nov 2020.

  1. bertles01

    bertles01

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    Hi folks,

    I have quite a few small historic cracks in the external render on the front of the house (built c. 1880). Pic attached.

    I was going to do the usual rake out into a v, pva, fill, sand, paint job, but not sure what's the best filler to use. I normally use Easifill inside but don't know if that's up to the job externally?

    Grateful for any thoughts.
    Cheers,
    Bertles
     

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  3. tel765

    tel765

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    Sand and cement plinths are often previous attempts to deal with damp - they dont work instead they can cause further damp problems.
    Render should be cut back 50mm from ground contact or you will get capillary action.
    Render should not bridge any mechanical DPC.

    The Planter is a bad idea and should go.
    Its possible that the ground level has been raised since the air bricks were installed?

    About 5 independent cracks can be seen on your bay render, & one behind the planter.
    Polyurethane is often used to fill raked out render cracks.
    Do the cracks or damp signs show inside?
     
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  4. lostinthelight

    lostinthelight

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    Pva externally ?? Sbr is better
     
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  5. tel765

    tel765

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    What do you mean Pva?
     
  6. bertles01

    bertles01

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    Thanks for the replies.

    Previously when I've filled cracks inside I've put a coating of pva on after raking out but noted on the SBR.

    tel765 - The planter is already on the list to go before winter... the previous owner had a lot of strange ideas. The ground level has probably come up to match the height of the newish paving stones, so maybe 50mm or so but I don't think much more than that. There are 8 houses on the street and all have the same render and similar ground levels. There's no obvious signs of damp on the internal walls and no cracking. I'll take a look at polyurethane fillers.

    And don't get me started on the airbricks - the two big ones don't actually go into the house so not sure what the point of them is (I can see under the floor from the cellar) and there's one in the middle which has been filled over at some point so there's no ventilation at all to the crawl space/cellar. Another job for the list!
     
  7. Grantx

    Grantx

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    You can see under the floor. Then the airbricks are doing precisely what they were designed to do: introduce airflow under the floor, albeit in the cellar.

    You need to establish the extent of the cracks; not just the actual what-you-can-see, but what you can't. Tap the rendering near the cracks with your knuckles (or something harder) and if it sounds hollow, then the rendering has become detached from its surface. It needs to be broken off and re-rendered.

    To stop rising damp on the render, as noted above, the render has to be removed all round from the ground to about 9 inches or 225mmm above. Further, you have to fix a drip bead along the bottom edge of the rendering, and render over this. This will keep surface water from dripping onto the face of the brickwork below.

    Out of interest, is yours a London house?
     
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