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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.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.

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    • CommentAuthordelprado
    • CommentTimeMar 7th 2018
     
    I am not sure I trust them - JUB, Parex etc?
    •  
      CommentAuthorfostertom
    • CommentTimeMar 7th 2018
     
    Why - any particular stories/experiences?
  1.  
    Hi Delprado,

    What do you not trust - Specifications, longevity of materials, quality of reps, below-ground details, solidity of completed system?

    Are you going for graphite EPS?
    • CommentAuthordelprado
    • CommentTimeMar 7th 2018
     
    my main concern is that they seem to use acrylics and I worry about moisture getting trapped behind them
  2.  
    All the acrylics I have seen are marketed as breathable or what ever term you want to use that signifies that it allows the passage of water vapour so moisture getting trapped behind them should not happen. The stuff has been around for many years and if trapped moisture was a problem I would expect to see spalling or other signs of frost damage - and it doesn't happen.
    • CommentAuthorgravelld
    • CommentTimeMar 7th 2018
     
    From my experience most of them offer a range of renders including silicone or silicate. Some also will do mineral, cement based.
    • CommentAuthorgravelld
    • CommentTimeMar 7th 2018
     
    My main concern is damage. Can a few mm of render on some EPS withstand a ladder being whacked against it?
  3.  
    I think a lot of the adhesive and base coats are cement-based. Even if you stick on a breathable EPS board with them, how does it affect the overall breathability. And re the ladder, yes, I think. We've had ladders against some.
    •  
      CommentAuthorfostertom
    • CommentTimeMar 8th 2018
     
    The acrylics are tough through flexible resilience, on their embedded glassfibre mesh.
    • CommentAuthorwookey
    • CommentTimeMar 9th 2018
     
    Mapei had a genuinely flexible render on display at ecobuild - you could bend it back and forth 30 degrees. Very impressive. Recommended for high-impact/high-risk areas.
    • CommentAuthorgravelld
    • CommentTimeMar 10th 2018
     
    Wow!
    • CommentAuthordelprado
    • CommentTimeMar 11th 2018
     
    Nick P - thats exactly my concern - my passiv haus handbook says the outside must be much more vapour permeable than the inside for obvious reasons
    •  
      CommentAuthorfostertom
    • CommentTimeMar 11th 2018 edited
     
    Posted By: delpradothe outside must be much more vapour permeable than the inside for obvious reasons
    Not obvious - and in fact not true - obsolete conventional wisdom, not supported by WUFI studies.

    Anyway, cement doesn't necessarily equal low permeability.
    • CommentAuthordelprado
    • CommentTimeMar 11th 2018
     
    hi fostertom, does that mean in your view the vapour permeabiluty of the outside is not relevant at all - why is that>?
    •  
      CommentAuthorfostertom
    • CommentTimeMar 11th 2018
     
    No, for a 'breatheable' solution, it all has to be very or moderately permeable; the overall permability matters, as does position in the sandwich of materials that are better kept dry; but a gradient from in to out doesn't seem to matter.

    As always, that was my findings but no one should take it as gospel, unless paying me a fee, in which case I'd re-check the exact build up, maybe local climate too - so check it yourself!
    • CommentAuthorSilky
    • CommentTimeMar 11th 2018
     
    couple of thoughts

    1) in Germany bird damage is apparently a major problem for polystyrene+render systems, not an obvious one but apparently they peck holes which go unnoticed, and then water leaks in, moisture build-up behind render

    2) on larger buildings think about what happens when you need to put up scaffolding ( i.e. to paint the render after 15 years, roof work etc. ), typically they drill straight through to fix the anchors and then patch up with foam + render afterwards, I wonder how safe that is

    3) if you care about what happens at end of life think about the mess that has to be removed, all that polystyrene bonded to the wall, and plastic meshes and render all bound together.. no way to recycle that mess, straight into landfill

    I think it's too soon to say, but if I did it I would want something that lasted at least 50 years, better 100, I think you'd stand a better chance with wood-fibre board and lime renders, better still with some cladding and keep the rendered areas to a minimum, surely easier to maintain in the long-term. So in answer to the original question rockwool or cellulose within a framework+ wood fiber sarking board + render or cladding seems like a sensible system for EWI
    •  
      CommentAuthordjh
    • CommentTimeMar 11th 2018
     
    Posted By: delpradoNick P - thats exactly my concern - my passiv haus handbook says the outside must be much more vapour permeable than the inside for obvious reasons

    Mine isn't. Obviously the reason isn't obvious to me.
    • CommentAuthordelprado
    • CommentTimeMar 11th 2018
     
    Moisture generally wants to move from inside to out, due to the pressure difference and heat difference. The risk of interstitial is therefore greatest in this direction, especially when you have a rendered house which essentially all but eliminates "reverse" condensation from the outside in, therefore you want it to be able to freely leave outward if it finds its way there. And of course not get there in the first place, hence VCL internally. In fact, I can see the logic of complete lack of vapour permeability internally and as much as you can get externally for same reason.

    Anyway, dont believe me, just believe the passiv haus handbook!
    • CommentAuthorrevor
    • CommentTimeMar 22nd 2018
     
    I was going to EWI my stone farmhouse until I went to see a job that had been done reasonably locally, It was a damp day and I could see the joints between the insulation boards. Due to fixings etc the render was badly stained. I elected to EWI but with cedar cladding which was painted and an air gap between the insulation and the cedar. The other advantage was It was within my skill set, rendering to an acceptable quality would not have been. This way I reckoned insulation would not get damaged, the wood if got damaged is readily repairable. As such I am very pleased with the result. As I was also reroofing completely the house and extension I had the advantage of being able to build in v deep soffits to accommodate the insulation and cladding.
    •  
      CommentAuthorfostertom
    • CommentTimeMar 22nd 2018
     
    Pattern staining is due to either gappy board installation, or using the bedding cement in the board joints, and for the fixings using a non-insulating type not intended for EWI - i.e. one way or another uneven insulativeness, leading to surface temp variation hence local variations in condensation (or not) which can discolour in itself, or lead to different algae growth.

    Properly installed, should be no pattern staining.
  4.  
    Revor, what EWI material did you use and, assuming a ventilated gap between rainscreen and insulation, what is the position re fire resistance? Is the insulation un-coated, or did you do a rough hide-it-behind-cladding render coat?
    • CommentAuthorgravelld
    • CommentTimeMar 22nd 2018
     
    Were the boards still stuck to the wall Revor or did you create a framework and filled? I like the Larsen Truss approach, I think it has a lot of benefits and in a money-no-object project it's the way I'd go.

    Only, money is an object.
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