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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthorAndyP1
    • CommentTimeFeb 6th 2021 edited
     
    Hi, we built our eco home in 2011 and finished 100mm wood fibre boards with Glaster lime render. After only a couple of years the render discoloured, flaked and pitted and looked terrible. Manufacturers blamed the plasterers and the plasterers blame the product, after years of hassle eventually specialist repairs done and applied limewash. After only 9 months though the limewash is wearing and I am now sick of the sight of it. My question to you lovey people is what options (other than what we have now) do I have for finishes if I hacked off the render?
    •  
      CommentAuthordjh
    • CommentTimeFeb 6th 2021 edited
     
    Posted By: AndyP1After only 9 months though the limewash is wearing

    How many coats of limewash have you put on? It's been a pretty wet year so I'm not surprised if it's worn more than usual. When we did ours, the plasterer put on a couple of coats of limewash and told us to keep adding coats for a while and then regularly thereafter. The wall looked a bit patchy-coloured but did have a nice birefringence.

    Cowsheds got new limewash every year. Instead I splashed on some Beeckosil and got that put on instead. That's a four-layer product that starts with an acid wash IIRC, but is supposed to last 10-15 years before needing repainting. It looks much more uniform but sadly isn't birefringent and still looks pretty much as it did five years ago. Keim is the main alternative; I chose Beeck because they claim their products are more natural.
    • CommentAuthorAndyP1
    • CommentTimeFeb 6th 2021
     
    We considered Beeck it the cost and complexity of application didn’t seem worth it for the re-coating time. The house had 3-4 coats of limewash last summer so surprised it is wearing all ready.
    •  
      CommentAuthordjh
    • CommentTimeFeb 6th 2021
     
    Posted By: AndyP1We considered Beeck it the cost and complexity of application didn’t seem worth it for the re-coating time. The house had 3-4 coats of limewash last summer so surprised it is wearing all ready.

    I'm all for a lazy life, so I was happy to pay to get peace of mind for a decade or more. And it seems to be working. I'm not surprised things are wearing more after last year's rain. I seem to remember talk of 15 or 16 coats of limewash being desirable. They have to be thin to go on properly, I think.
    • CommentAuthorkristeva
    • CommentTimeFeb 6th 2021
     
    Limewash definitely has to be applied thinly in back breaking multiple coats. I would hate to have to lime wash a house. Talk about groundhog day.
    • CommentAuthorAndyP1
    • CommentTimeFeb 6th 2021
     
    We were quoted £3000 to apply Beeck so sadly out of our budget, wondering what other options we have, cement fibre panels maybe, not very environmentally friendly though.
  1.  
    I don't know anything about Glaster lime render, but have had success with Baumit MC55 and silicone silicate render. Only over a few years, but more than the 2 after which yours started degrading, if that's any help.
    • CommentAuthorAndyP1
    • CommentTimeFeb 6th 2021
     
    Glaster is a Ty Mawr product, lime render with recycled glass aggregate, it looked nice initially, now looks like the scruffy, wish we had never heard of it now😩
    •  
      CommentAuthordjh
    • CommentTimeFeb 6th 2021
     
    I'm confused - is it the render or the limewash that is a problem. I understand there was initially a problem with the render (or how it was applied) but thought that had been fixed and that we are now discussing a current problem with the surface finish of limewash. Is that not correct? Is there still a problem with the render?
    • CommentAuthorAndyP1
    • CommentTimeFeb 7th 2021
     
    DHJ The render was repaired and then the limewash used as a finish as the repairs would be patchy.
    • CommentAuthorSimonD
    • CommentTimeFeb 7th 2021
     
    Similar to Nick Parson's suggestion, have you looked at silicate or silicon resin paints for lime render? Many, if not all the woodfibre manufacturers use such a paints as the final coat on their systems. May be worth a try before hacking off all your render and starting again.

    https://www.promain.co.uk/blog/resource-centre/paint-lime-render/
    https://www.lime-green.co.uk/products/lime-render/Silicate-Finish-Paint
    https://earthbornpaints.co.uk/faq/is-the-ecopro-silicate-masonry-system-suitable-for-lime-rendered-exterior-surfaces/
    • CommentAuthorAndyP1
    • CommentTimeFeb 7th 2021
     
    Simon D I think this is what we were quoted £3k to have put on, they said it would needed to be repainted every 10 years??
    •  
      CommentAuthordjh
    • CommentTimeFeb 7th 2021
     
    FWIW, Beeck and Keim are silicate paints. The original and IMHO the best.
    • CommentAuthorSimonD
    • CommentTimeFeb 8th 2021
     
    Posted By: AndyP1Simon D I think this is what we were quoted £3k to have put on, they said it would needed to be repainted every 10 years??


    Posted By: djhFWIW, Beeck and Keim are silicate paints. The original and IMHO the best.


    Yes, Beeck (and Keim) are mineral silicate paints. However, Beeck has several different options for it's mineral paints including a 2 pack, single pack, a paint with 'active silification' etc - e.g. Beckosil and Renosil. So it depends on what you were quoted for. Also have a look at the various application instructions. I believe there may be more involved in application with the Beeck system than say for Keim, which may only require a primer coat, if at all. This is similar to the Mapei silicate paint requiring just a primer and/or basecoat.

    I don't have personal experience of the Mapei silicate paint, Silexcolor, but it is massively cheaper than Keim and possibly around 1/2 the price of Beeck Renosil.
    • CommentAuthorAndyP1
    • CommentTimeFeb 8th 2021
     
    Thanks for the additional info, looks like I have a few options either way I need to do something with limewash by the sounds of it, either get it off us much as possible if going the silicate route or put loads more coats on if sticking with it.
    •  
      CommentAuthordjh
    • CommentTimeFeb 8th 2021
     
    Posted By: SimonDI believe there may be more involved in application with the Beeck system than say for Keim, which may only require a primer coat, if at all. This is similar to the Mapei silicate paint requiring just a primer and/or basecoat.

    I think it depends on comparing like for like. The Beeck system starts with either sandblasting the surface* or applying the acid etch on new surfaces. We chose the acid etch. The Mapei system requires sandblasting*; no choice offered. Both systems then require a primer, followed by two coats of the paint. I do agree that the Mapei system is cheaper. :bigsmile:

    * or similar procedure.
    • CommentAuthorSimonD
    • CommentTimeFeb 8th 2021
     
    Posted By: djh

    * or similar procedure.


    I hate sandblasting, too messy and requiring lots of expensive equipment. Personally I would just sand it as prep. With something like a Mirka sander it can be done dust free too - even of you might get through a few dust bags. I have a Mirka Deros which almost makes sanding a pleasure :smile:
    •  
      CommentAuthordjh
    • CommentTimeFeb 9th 2021
     
    Fine, the point is it has to be done whichever paint system you choose (unless the paint system offers an alternative).
    • CommentAuthorSimonD
    • CommentTimeFeb 9th 2021
     
    Posted By: djhFine, the point is it has to be done whichever paint system you choose (unless the paint system offers an alternative).


    You have to prep any surface you're going to paint, that's pretty much a given if you want a decent finish.

    My point was "I believe there may be more involved in application with the Beeck system" in the context of that there are several options of types of mineral paints made available by Beeck (see above). To expand upon this it may be required to use up to 5 different 'layers' of the Beeck system, depending on the substrate. It was also in the context of the £3k quote for application which depends on what was being proposed by the proposing contractor - which, of course, we don't know.
    • CommentAuthorAndyP1
    • CommentTimeFeb 10th 2021
     
    Simon D yes the quote we had was for this 5 stage system, seemed extremely complex and given Welsh weather something that could go on for a long time! Given the softness of limewash would pressure washing it of instead of sanding be possible? Thinking of the dust.
    •  
      CommentAuthordjh
    • CommentTimeFeb 10th 2021
     
    It's a lot faster and easier to apply an acid etch than sand or sandblast IMHO. You have to remove the surface sintering so I don't think a wash would be effective.
    • CommentAuthorSimonD
    • CommentTimeFeb 11th 2021
     
    Posted By: AndyP1Simon D yes the quote we had was for this 5 stage system, seemed extremely complex and given Welsh weather something that could go on for a long time! Given the softness of limewash would pressure washing it of instead of sanding be possible? Thinking of the dust.


    Posted By: djhIt's a lot faster and easier to apply an acid etch than sand or sandblast IMHO. You have to remove the surface sintering so I don't think a wash would be effective.


    I think it is easier and faster to apply acid etch on new render, but having looked at the data for Beeck's etching fluid, it is recommended that existing surfaces are pressure cleaned before etching.

    There is also a note that unsuitable substrates for etching include ETICS, external thermal composite systems, which, technically, your system is AndyP1.

    You can find all the data here: https://www.beeck.com/en/products/bmf-product.php?p=etching-fluid

    However, with your render, do you know its thickness as ETICS will typically be about 10mm (6mm base coat with 3-4mm top coat) whereas an hydraulic lime render on woodfibre would typically be 15mm (9mm base, 6mm top coat). This may play to your favour but I'm not familiar with Glaster.

    Given all these questions and the circumstances, you'll probably want to tread carefully, trying to pressure wash a small area of the render first to see how this works and maybe like the Keim prep instructions maybe use a stiff brush in places if needed. I guess your main render now isn't the problem here as it's been repaired, just the look of the limewash?
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