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External render blown/damp/issues, best solution?

Discussion in 'Plastering and Rendering' started by robodelfy, 29 Jun 2020.

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  1. robodelfy

    robodelfy

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    Hi, the back of my house is a bit of a mess. I started chipping off a patch of blown render and more and more came off. I've taken it back as far as I can and it feels very solidly adhered in the places that are left, almost impossible to get any off with a claw hammer or chisel etc.

    The bottom left section was extremely thin render, almost like a tiny layer of sand then paint. And I was able to just scrape back that patch with a scraper, and its very damp underneath. I also had some damp issues in this corner internally. Could this just be that the render/paint had worn so thin that water got in to the wall? If so, how would I remedy this now considering its been left for many years this way. I feel stupid for not doing anything but I was renting it for years and out of the country.

    I spoke to some renderers, one said you could just scrape back to whats solid and then patch it up and paint, cheapest solution. Others said the render is too old, you need to get it all off. But it's nearly impossible to get the solid bits off! Also, these guys didn't know about the damp bottom left corner.

    One of them said the best possible thing would be to get External Wall Insulation (EWI), but this is very costly. They said this could be done over the current wall once the hollow/blown bits are chipped off.

    The only other thing, is that in the second picture if I knock on that area the wall sounds a hollow. This worries me, what can you do about that?

    Sorry for all the questions, but I'm already on borrowed money and time! Any advice would be great, what would be some of my best options.

    Also, is it really bad to leave the wall exposed as it is? Should I be looking to cover the areas I chipped the render away somehow, if so how!?
    thanks

    20200629_151705.jpg 20200629_135311.jpg
     
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  3. KenGMac

    KenGMac

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    robodelfy, good evening.

    If it were me? I would have all of the old Roughcast render Off, why because if some has failed then a lot more is liable to fail???

    Do not worry about leaving the substrate exposed it may assist in allowing it to dry of a bit [not in this weather]

    At one time that elevation had a lot of ivy?? attached to it.

    OK best [most expensive] will be the external insulation method.

    There seems to be some sort of cement wash?? or external masonry paint then the roughcast on top of a form of block I do not recognise?

    As for removal of the remaining roughcast?? try using a block of wood and a heavy hammer, place the wood on to the roughcast and hit the wood with a heave hammer, the shock can assist in loosening the render??

    Or? borrow or hire an SBD Drill with a spade but that can / will scrape the surface of the blocks.

    Off the wall suggestion??? [sorry about that] how about clearing off the old roughcast and re-decorating the blocks??

    Ken.
     
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  4. robodelfy

    robodelfy

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    Thanks for the detailed response. The majority of the pebble dash does seem very well stuck on, I think the areas where it came off was due to a bad patched in bit that then let water in. But its impossible to say.

    Yes I thought possibly it would allow it to dry once taken off, but its only that bottom left section that is wet. It is south facing but we have no sun right now!!

    It had a grape vine growing up it which I recently removed.

    The block you don't recognise...someone I sent the photo to said that some time ago they rendered houses and then scratched lines in to mimic blockwork. If you look closely in the photo it looks like this could be that. I didnt notice today, but then none of it came off, only the rough cast came off. I will be able to look closer tomorrow. If that is the case, then I guess its best to just chip off the few hollow sounding bits of that too, and re render.

    I'll try the block of wood, but as I said in 70% of the wall, its really hard to get off!
     
  5. KenGMac

    KenGMac

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    Agree totally, but??? [generally] when such work is undertaken there is only one line scratched on to the surface of the cement render??

    Ken.
     
  6. robodelfy

    robodelfy

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    On my second photo you can see how the cracks run straight through the assumed 'scratched' lines, this makes it seem very likely it is just render. I will have to check tomorrow


    I'm still just unsure how to approach sorting this mess out! :)
     
  7. Alastairreid

    Alastairreid

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    Why have you started another thread asking the same question?...you will get the same answers.
     
  8. robodelfy

    robodelfy

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    Sorry I didnt use forums much before this job. I thought I'd post again because I uncovered new stuff and had new questions, but in the future I'll just add to the old post. I thought nobody would see it

    And I didnt get some quite helpful different answers :)
     
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  9. robodelfy

    robodelfy

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    Yeah so it is just render with scratches in!
     
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  11. Alastairreid

    Alastairreid

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    You will need to make sure the surface you are scratch coating has a good key.
    No loose material, paint with an sbr slurry and let dry.
     
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  12. bennymultifinish

    bennymultifinish

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    theyve pebble dashed over old smooth render .
    no mechanical key and probably no waterproof adhesive. doomed to eventual failure. you will have to remove the pebble dash and go from there.
    personally , the last thing i’d do in your situation is hit it directly with a hammer , block of wood or no block of wood. you may find yourself loosening the original stuff also.
     
  13. robodelfy

    robodelfy

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    Thanks, I've been told that on these victorian houses, that a lime render should be used, and therefore it would be best to get the render off underneath the pebble dash, but that feels quite impossible with the tools I have. Of course I'm worried about damaging bricks underneath too.

    I've got someone coming over later to have a look and give their opinion, so we'll see what they say
     
  14. Harry Bloomfield

    Harry Bloomfield

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    That is a thin coat of render, on top of earlier render. The early render has numerous cracks in it and explains why a thin second coat was put on, to disguise those cracks. There seems to have been no attempt to roughen the surface of the earlier render, so the second coat has failed. I would suggest to deal with it properly, both coats of render need to be removed, to allow it to be done properly.
     
  15. robodelfy

    robodelfy

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    Yeah it does look that way. There was subsidence a long time ago which could explain the cracks possibly. The more I read too, if you have a solid wall victorian house, you should be using lime renders which these don't seem to be.

    I'm looking into external wall insulation but its expensive. I just want to do it properly so it lasts. Originally I hoped I could just patch it up so it was ok for a year until I had more money to do the EWI
     
  16. bennymultifinish

    bennymultifinish

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    it’ll be fine for a year or even 2 years. why bother.
     
  17. robodelfy

    robodelfy

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    Fine as it is?
     
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