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Housing - New Build: Hairline grid cracks in 3 year old EWI

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  1.  
    So, good friends of mine here in sunny semi-rural Italy bought a new build with EWI. We think it is 100mm EPS. It is covered in a brittle, thin feeling concrete coloured render and then has been painted. Friend complained about several small patches of flaking paint on not their most exposed wall. On closer inspection I found a grid pattern of hairline cracks pretty much everywhere I looked - not 100% coverage by any stretch but even in a covered portico well away from the weather (but still outside) there are these cracks.

    I assume it is movement from the EPS boards coming through the render. The flaking paint does not appear to propagate from the cracks and anyway is confined to some very small areas - I think the paint is a red herring from, what I am guessing, is a more serious problem. But is it? What is the prognosis for EWI with such cracks? Is it a common problem? Is it serious/so what? Most worrying for my friend (assuming this is a significant problem) is that the EWI was fitted by the builder - a builder with known cash flow problems and who has fought for every penny through every aspect of this build.

    Anyone have any experience of this sort of problem? Ta
    •  
      CommentAuthordjh
    • CommentTimeApr 2nd 2017
     
    I think we're going to need more information, ideally some photos, to have much of an idea. I'd think it is more likely the result of thermal movement, plus a fairly brittle render with low tensile strength. But are the cracks regular? What is the spacing? How old is the render, is it simply cracks as the render sets? What type of render is it? Does the render contain something to increase its tensile strength, such as fibres or a mesh?
  3.  
    Yes regular cracks, perhaps 1m square but only looked quickly and didn't have a tape measure with me - I'll confirm later today.

    Render is not more than 4 years old.

    Render is 'thin' ie def less than 10mm thick - I have never experienced Thin Render but from tapping the render on this house there is no doubt that it is only a few mm thick.

    As to the type of render, the render feels brittle, ie is not a flexible silicony type thing - more than that we will not get.

    No idea as to whether the render contains a mesh but I thought it was impossible for suck a system not to contain render.
    • CommentAuthorHollyBush
    • CommentTimeApr 3rd 2017
     
    Is there any equivalent to the UK's 10 year NHBC scheme?
  5.  
    The EWI adhesive that I have used as part of the thin render system finishes up about 3-4 mm thick with glass mesh embedded in to it. the adhesive/render is flexible and where it is thin and without the mesh then you can depress the surface and so depress the underlying EPS without cracking the render. The thin film acrylic toip coat is also flexible. The addition of the glass mesh acts like rebar in concrete and stiffens and strengthens up the whole system.

    IMO the thin film render and acrylic top coat should not crack as there should be enough flexibility and strength within the components to be stable. After all the industry has spent a lot of research over the years to get the components working together in an acceptable manner. (a German study of 30years old EWI showed no deterioration).

    Some investigation should be undertaken to see what materials were used, what thicknesses and is the mesh included. The look at the specifications and or the bills to see what was charged for. And go from there.

    If the adhesive was not used for the render I wonder what was used to stick the EPS sheets to the wall???
  6.  
    OK but what I am asking is: so what?

    This is Italy so even if there were some sort of 10 year guarantee you can guarantee it wouldn't help!

    I know thin coat should be flexible and shouldn't crack - this stuff just feels really brittle and inflexible.

    Almost by definition (in that there are cracks) an authorised system wasn't used.

    What I really need (he really needs) is to know what happens if they do nothing, except maybe a repaint.
  7.  
    If it was repainted then you have new paint on a bad base - IMO not so good.

    If the faulty render is just cracking then maybe putting a suitable (correct) thin coat render with mesh over may solve the problem.

    If the cracking render is also flaking off then nothing put on top will adhere any better than the flaking off base.

    If it is flaking off perhaps a solution could be to put another layer of EWI over the whole lot, say between 2 to 5 cm thick and mechanically fix through to the wall - especially if you are not sure of the adhesive or adhesion of the original EWI

    Any chance of getting the builder to do something (under the watchful eye of someone who knows what should be done) perhaps via the trade licensing authority or what have you in Italy. There must be some method of controlling building practices but I suppose there is the chance that the time it takes may not be worth the hassel.
    • CommentAuthorgyrogear
    • CommentTimeApr 3rd 2017
     
    maybe this might help ?

    https://failures.wikispaces.com/EIFS+Failures+Overview

    gg
    •  
      CommentAuthordjh
    • CommentTimeApr 3rd 2017 edited
     
    You said the cracks were regular and at approximately 1 m intervals. That's a strange size; what size are the EWI insulation blocks? If you or your friend are serious about finding a cure then I think you'll need to find the least conspicuous, least exposed corner and break a small piece of render off, with a witness. Then it will be obvious how rigid or flexible the render is and whether it contains a mesh or fibres.

    I'd suggest that the only real cure is probably another coat of a flexible render with a mesh or fibre. But until you've determined what the cause of the cracks is, that's probably premature.

    edit: and as PiH says, if the existing render is not well-attached then there's no point adding another layer.
  10.  
    I am awaiting the correct measure of the cracks. The house has not been repainted...yet The assumption is that the builder will suggest that as a solution.
  11.  
    Posted By: djhYou said the cracks were regular and at approximately 1 m intervals. That's a strange size; what size are the EWI insulation blocks?

    Over here EPS comes in one size - 100cm x 50cm. they are typically (should be) put on "stretcher bond" so cracks at 1m intervals would make some sense.
    • CommentAuthorringi
    • CommentTimeApr 3rd 2017
     
    Were the mesh sheets not overlapped with each other? Or no mesh sheets used.
  13.  
    Unfortunately, we do not know what products were used let alone how they were used. I'll post a couple of photos in the next 48 hours. Also there are some much bigger cracks where the render joins the hit and miss brickwork windows surrounds.

    What I really, really want is some sort of answer to my question - my reason for posting: so what? By that I mean is this issue just unsightly and aesthetic or more serious? These cracks must be through the render but is it likely the cracks go all the way through to the EPS. Is a hairline crack going to allow water in? Will the water delaminate the render in time through freeze thaw? etc.

    The cracks must have been caused by thermal expansion, perhaps exacerbated by new EPS, who knows, but it doesn't seem likely to me that this issue would arise in such a widespread manner on different walls of the house through incorrectly attached EPS. Also from my knowledge of local building skills I would expect that the least likely part of the entire EWI process for them to get wrong would be attaching the EPS blocks. With that in mind, would simply another render coating (ie full acrylic system) be a solution. Extra thickness of even very thin EWI is not an option given the flush windows and doors!
  14.  
    So, Full details are:

    1. On the large, west facing, external wall most cracks are along the lines of the insulation blocks; all are exactly 100 cm long and 50 high. It is also possible to 'see' the edges of the insulation blocks even when there is no cracking. On this wall it is also possible to see a few round (4 cm diameter) fittings through the rendering.

    2. On most of our walls there is also continuous wider vertical-ish cracks to the sides of where bricks frame a doorway.

    3. Finally, there are hairline cracks on the two uninsulated walls that abut the house. These walls appear to be rendered and painted in the same way as the house. These cracks are all lower down on the walls and irregular.

    So, I assume this will cause failing of the render, but how long might this take or rather how long can this be left before the repair becomes bigger? There's no chance the builder will sort this out and no regulatory option that would end up in a solution. A full re-render with a professional flexible render system is I assume the only solution if the blocks are attached correctly.

    So, how to be sure the blocks are attached correctly?
    What does correctly look like?

    Perhaps drilling a very shallow hole and applying extra HQ fixings would be sensible anyway given the expense of re-rendering the whole house.

    Interestingly, the builder built 2 houses on the same plot at the same time and both are affected.
    • CommentAuthorgravelld
    • CommentTimeApr 4th 2017
     
    "So what?" Personally I don't think it's acceptable from an aesthetic point of view, let alone from a structural one.

    I'm very worried about this for my own project, hence my annoying posts about using trusses and cladding, or whatever other way of avoiding render.

    Anyone know somewhere (UK) that I can actually "feel" how flexible these modern renders really are?
    •  
      CommentAuthordjh
    • CommentTimeApr 4th 2017
     
    Posted By: GotanewlifeSo, I assume this will cause failing of the render, but how long might this take or rather how long can this be left before the repair becomes bigger? There's no chance the builder will sort this out and no regulatory option that would end up in a solution. A full re-render with a professional flexible render system is I assume the only solution if the blocks are attached correctly.

    The cracks will allow water in, even if they are hairline. If it's subject to freezing then that will widen the cracks. Even if not there might be an accumulation of water behind the render. Depending on how well the render is attached or the EPS is attached, something may eventually fall off.

    I think your friend needs to find somebody who knows what he's looking at - maybe a surveyor, or a good builder - to assess the situation. And I still think a destructive investigation will be necessary before he can decide on what repair is necessary. It really comes down to your friend's approach to problems like this, and to his finances.
    •  
      CommentAuthorfostertom
    • CommentTimeApr 4th 2017
     
    Posted By: djhThe cracks will allow water in, even if they are hairline
    Not just 'allow' - hairline cracks actively suck or pump water in, by capillary attraction - but don't correspondibngly conduct it out again 'when the sun shines'. So capillary cracks are a one-way (inward) pump.
  18.  
    Posted By: djhAnd I still think a destructive investigation will be necessary before he can decide on what repair is necessary.

    +1
    To me it is beginning to sound like the render was put on too thinly and without mesh. It also may not be the EPS adhesive used as the render or the acrylic thin film render used as the top coat.

    It also begs the question as to what was used to stick the EPS to the wall. Destructive investigation is the only way to find out.

    Another issue that may arrise is that if the EPS was attached to the wall with 6 or 8 blobs of adhesive per sheet then there can (will) be a gap between the insulation and the wall. if there is also any gap at the top and bottom of the insulation then a convection air flow will occur between the insulation and the wall nullifying the effect of the insulation.

    I don't think a surveyor, or a good builder would put their name to anything other than a complete re-render with the correct specification materials, - they just wouldn't want the risk of recommending a cheap(er) fix.

    Options (IMO)
    1 do nothing and see what falls off over time
    2 put on a coat of the acrylic top coat render and wait to see if the cracks reappear, if so do 3
    3 re-render the EWI with the correct specification render, mesh and top coat.

    If option 3 is chosen it would be as well to put in mechanical fixings as well (if they were not put in in the first place) to help support the unknown quality/quantity of adhesive.

    In any event it is probably worth making sure that there are no gaps at the top and bottom of the wall / EPS interface (cans of squirty foam) because I would bet that the EPS was stuck on with blobs of adhesive (or mortar) as this is the quickest and cheapest way of doing it - but it does rather muck up the insulating effect.

    Over here the labour costs roughly get divided in to 3, 1/3 to put on the insulation, 1/3 to put on the render coat and 1/3 to apply the thin film acrylic coat.
  19.  
    OK guys. Thanks everso. Pretty much accords with my views on it all but I really wanted that clarification that this issue is not just aesthetic. For the sake of completeness I will post a couple of pics idc.
    • CommentAuthorGotanewlife
    • CommentTimeApr 4th 2017 edited
     
    Posted By: Peter_in_HungaryAnother issue that may arrise is that if the EPS was attached to the wall with 6 or 8 blobs of adhesive per sheet then there can (will) be a gap between the insulation and the wall.

    As I mentioned it is possible to see lots of 4cm ish diameter raised areas through the render - these can only be EPS fixing mushroom heads. I take it you missed that or are you saying dabs and fixings, which I think I have seen as part of one system before but I don't think is common..
  21.  
    Posted By: Gotanewlife
    Posted By: Peter_in_HungaryAnother issue that may arrise is that if the EPS was attached to the wall with 6 or 8 blobs of adhesive per sheet then there can (will) be a gap between the insulation and the wall.

    As I mentioned it is possible to see lots of 4cm ish diameter raised areas through the render - these can only be EPS fixing mushroom heads. I take it you missed that or are you saying dabs and fixings, which I think I have seen as part of one system before but I don't think is common..

    If there are 4cm raised areas then yes this is going to be the EPS fixing mushroom heads. (sorry I missed that!!) But this only goes to show how thin the render is and how badly the fixing were put in. The fixings should be put in so that they slightly depress the EPS and the resulting depression should be filled before the render coat. The dabs are the adhesive fixing the EPS to the wall and IMO will allow convection air currents between the wall and EPS which will carry away the heat.

    All in all it sounds like a real cowboy job.
    • CommentAuthorbarney
    • CommentTimeApr 4th 2017
     
    Italian builders - who'd have thought it !!

    Barney
    • CommentAuthorGotanewlife
    • CommentTimeApr 4th 2017 edited
     
    Posted By: Peter_in_HungaryThe dabs are the adhesive fixing the EPS to the wall and IMO will allow convection air currents between the wall and EPS which will carry away the heat.
    Except as i mentioned there probably aren't dabs!!!!

    Anyway it is now a dead issue. The owner of the other house (a German) has taken advice and this is it:

    "After all these mails and blogs and me not knowing anything, I picked up the phone and called my brother-in-law who was the principal of a school for building techniques. They also do research for the building industry.
    He passed me the number of the head of department of Verbundsysteme ( the technique our houses were built with). Here is his answer:

    It takes up to 5 years for a house to settle. Before that term no repair should be made at all. Same problems can reoccur.Hair thin cracks are not an issue unless the lower part of the render isn't cracking. And (local builder) has checked this today. It's not broken. Attention should be paid when dust and dirt start settling on the cracks. This could mean the cracks can be permeated. If this occurs, the easiest and best way to solve the problem is painting the outside walls with latex or caoutchouk paints which will seal the wall again.

    He was also very clear about the relevance of cracks: after 10 years 80 % of all houses present cracks and only 1% of them affects the walls negatively. Reasons for the cracks can be endless. In our case, he sustains that the insulation material was too fresh (it should always be stored for a long time before using it which nobody does) and it's volume shrank, causing the the cracks exactly along its shapes.

    He suggests to wait confidently and act only if dust acted dirt visibly start covering the cracks.As far as I am concerned, I will follow his act device."

    So, a dead issue now.
    •  
      CommentAuthordjh
    • CommentTimeApr 4th 2017
     
    Posted By: Gotanewlifethe insulation material was too fresh (it should always be stored for a long time before using it which nobody does)

    Three months is the figure I've seen mentioned, FWIW.
    •  
      CommentAuthordjh
    • CommentTimeApr 4th 2017
     
    Oh and ...
    Posted By: Gotanewlife"After all these mails and blogs and me not knowing anything, I picked up the phone and called my brother-in-law who was the principal of a school for building techniques. They also do research for the building industry.
    He passed me the number of the head of department of Verbundsysteme ( the technique our houses were built with).

    You're not going to get better than that.
  26.  
    Yes it is nice to know that this render is correctly applied, that the cracks are normal and almost certainly won't cause any problems.
    • CommentAuthorgravelld
    • CommentTimeApr 4th 2017
     
    What. The. Fuck.

    Am I just totally naive in this? Why would anyone pay to have their house rendered if it ends up cracked, regardless of whether they are "hairline"?
    •  
      CommentAuthordjh
    • CommentTimeApr 4th 2017
     
    I don't think properly applied render should crack under normal circumstances. I certainly don't think the cracks are normal or acceptable but perhaps gotanewlife forgot an emoji?
  29.  
    errrr boys - be a sad day when I need an emoji to get across deepest of heavy sarcasm.:wink::cry:
    •  
      CommentAuthorfostertom
    • CommentTimeApr 5th 2017
     
    People believe what they want to hear.

    So all of this is part of a system-build (Verbundsysteme) technique? the client mentions 'our houses' (plural) so are there more of them nearby? showing same symptoms? It could have been poss to find out from a published system spec, what the materials, fixing etc are?

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