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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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    • CommentAuthorNanuchka
    • CommentTimeJan 26th 2022
     
    Hello, can anyone recommend an installer in Cornwall? Have been trying to find someone for SO long, albeit in a bit of a desultory manner. My house is a bit challenging as it’s not at all straightforward, and so builders come and look and I never hear from them again. Is all very discouraging.
    • CommentAuthorjfb
    • CommentTimeJan 27th 2022
     
    What insulation are you looking at?
    There are probably two main routes - trying to maintain a vapour open build up using lime/ breathable insulation (like woodfibre) or installing a vapour control layer and then installing 'normal' insulation like celotex/insulated plasterboard/etc.

    If it is woodfibre boards you could ask some of the main suppliers for installers they know - try Ty Mawr in Wales or Mike Wye.

    Internal wall insulation is a tricky thing to retrofit well so I can understand why you are not getting much interest.
  1.  
    Posted By: jfbWhat insulation are you looking at?

    External wall insulation (= EWI) or internal wall insulation (= IWI) ??
    • CommentAuthorjfb
    • CommentTimeJan 27th 2022
     
    Good point Peter!
    • CommentAuthorNanuchka
    • CommentTimeJan 28th 2022
     
    Hi jfb,
    At this point I’m desperate and would pretty much take anything!!
    Thanks for suggestions.

    Hi Nick! I did make contact with Robb, his contractor is a long way down Cornwall so I discounted as the idea of all those diesel miles upsets me! I shall revisit tho, thanks for reminding me.
    Anna
  2.  
    Posted By: NanuchkaAt this point I’m desperate and would pretty much take anything!!

    You don't say what you are trying to achieve and why.

    In terms of energy reduction wall insulation generally won't give a payback in any reasonable time scale however it will increase the comfort level of the house.

    EWI is better for the building, easier to avoid cold bridges and less disruptive for the occupants. If the roof overhang makes EWI difficult then the overhang is fairly easy to extend.

    In terms of energy reduction have you done the quick wins - loft insulation and draught proofing - oh and if you have any chimneys these can be a big source of heat loss.

    Whilst the above doesn't help in finding a contractor knowing what and why is needed will determine the direction in which to point - It might also give alternative solutions to get the same net effect. Do you have a target end result? If it is energy reduction what is your current heating source e.g. a 10 year old gas boiler could be 30% less efficient than a new one.

    By the way what makes the house challenging for wall insulation?
  3.  
    What is the house built of? Brick, stone, cob, cast concrete, timber?
    Is it Listed?
    Is it in a Conservation Area?
    • CommentAuthorNanuchka
    • CommentTimeJan 28th 2022
     
    Hi Peter,
    The house is dressed stone on front elevation (conservation area) has elaborate cornice work inside, the back is a higgledy piggledy mish mash of walls, levels and roofs with zero overhang. The very exposed side elevation is single skin, large, flat and blank with a couple of small windows, and a decent eaves overhang, and suffers badly with condensation, so it’s a relatively simple win and job, tho I know it won’t solve all problems. I’ve discussed it in a fair amount of detail with a sustainable buildings expert (thank you Nick Parsons!). The loft unfortunately isn’t an easy win as it’s got rooms, so will have to rip everything out and start over. I am planning to do it, but it’s much more invasive and expensive so can’t just yet. Is all such a headache!
    Anna
  4.  
    Posted By: Nanuchkaside elevation is single skin, large, flat and blank


    Is this also dressed stone or is it rendered?
    • CommentAuthorNanuchka
    • CommentTimeJan 28th 2022
     
    Dominic,
    The parts of wall I’ve seen exposed during various buildings works are constructed from strange (to me) blocks that look like they’ve been made of rubble! Yes to conservation area, it’s an Edwardian semi.
  5.  
    Hi, have you taken the approach of telling them exactly what you want and just asking the builder to install? I had zero success when I asked for their opinion but they (grudgingly) agreed to install my IWI when I specified everything in detail.
    •  
      CommentAuthorfostertom
    • CommentTimeJan 28th 2022
     
    EWI is far superior in many ways - IWI is a bit of a last resort with several snags, but may be appropriate, depending.

    EWI means making the walls thicker outward. Do you have land to enable that, or is your front elevation straight onto the public pavement, or is your side elevation straight onto neighbour's land? Would it be acceptable to change the external appearance?
    • CommentAuthorNanuchka
    • CommentTimeJan 28th 2022
     
    It’s rendered. Had the concrete render replaced with lime a few years ago which is when I saw the blocks.
  6.  
    cross posted
  7.  
    It sounds like the side wall could be externally insulated then.
  8.  
    But whether it is worth doing if the front wall can't be is a difficult one. I think we had a thread on here about a mix of internal and external insulation.
  9.  
    In an Conservation Area they won't want you change the appearance of the front elevation (the dressed stone)
  10.  
    The back could probably be done externally.
  11.  
    Posted By: Nanuchkaelaborate cornice work inside


    if this is inside the rooms on the front elevation, then you might be able to squeeze in a layer of Aerogel-backed board without affecting it.
    if not, then you would have to remove it, insulate with something cheaper, then reinstall. In both cases it will need reskimming over the boards anyway.
    • CommentAuthorNanuchka
    • CommentTimeJan 28th 2022
     
    <blockquote><cite>Posted By: modernvictorian</cite>Hi, have you taken the approach of telling them exactly what you want and just asking the builder to install? I had zero success when I asked for their opinion but they (grudgingly) agreed to install my IWI when I specified everything in detail.</blockquote>

    I have tried this, but perhaps I need to be more persistent!!
    •  
      CommentAuthorfostertom
    • CommentTimeJan 28th 2022
     
    I think this calls for a highly bespoke mix n match plan, in which small details at various locations will be all-important and should determine the local solutions - and make sure those all link up into the best total scheme possible, and affordable. In other words, employ an architect with practical experience of different methods and of listed-standard buildings. A tall order but not imposible.
  12.  
    Posted By: NanuchkaHi Peter,
    The house is dressed stone on front elevation (conservation area) has elaborate cornice work inside, the back is a higgledy piggledy mish mash of walls, levels and roofs with zero overhang. The very exposed side elevation is single skin, large, flat and blank with a couple of small windows, and a decent eaves overhang, and suffers badly with condensation, so it’s a relatively simple win and job, tho I know it won’t solve all problems. I’ve discussed it in a fair amount of detail with a sustainable buildings expert (thank you Nick Parsons!). The loft unfortunately isn’t an easy win as it’s got rooms, so will have to rip everything out and start over. I am planning to do it, but it’s much more invasive and expensive so can’t just yet. Is all such a headache!
    Anna

    The side elevation sounds like a good candidate for EWI. A quick calc. guessing the composition of the blocks gives about 3.8 u value. Stick 50mm of EPS EWI on and you get 0.66 and 100mm EWI gets 0.36 u values. The cost difference between 50mm and 100mm will be the difference between the cost of the EPS, other costs being the roughly the same. The same applies to the rear wall although without knowing the structure it is not possible to give any values. The lack of overhang should not be a problem as you can either extend the roof or (probably a cheaper option) put flashing on the top exposed edge of the EWI. If the flashing option is chosen then best to chamfer the top edge down and outwards to better shed rain.

    An option for the attic would be to insulate the roof internally over the existing with either insulated plasterboard or with EPS first and the plasterboard over (labour vs material cost would drive the choice). The disadvantage with this is that it costs internal space / head room but has the advantage of being both much quicker and cheaper.
    If you did rip it all out and redo, how much space would you have for the insulation? If your rafters are only 100mm or 120mm then by the time you have left space (50mm) for the ventilation there won't be much insulation without building down into the room space - by which time the advantage of ripping it all out and starting over might be lost. (Oh and if your ceilings are lath and plaster the mess of ripping out is unbelievable)

    If you want to see the results of the various suggestions here when put against what you have there is a good u value calculator at
    https://www.ubakus.com/en/r-value-calculator/?
    Choose the demo version. It gives the expected u value for your structure and indicates condensation issues. It is fairly self explanatory and can answer the 'what ifs' of proposed solutions.

    When insulating a house the building regs require that if part of a wall is upgraded then the whole wall must be brought up to current standards however there are get outs e.g. conservation area restrictions, impracticabilitys, cost / benefit ratio and probably a few others I don't know about. So best to run the plans past the building standards once you have decided what you will do.

    When posting here if you 'quote' then if you select the Html button below the input box the 'quote' is highlighted in blue - it just makes it easier the read.
    • CommentAuthorNanuchka
    • CommentTimeJan 28th 2022
     
    Wow, thank you so much for that detailed reply Peter! And for the quote tip - was wondering how to do it properly.
    • CommentAuthorNanuchka
    • CommentTimeJan 28th 2022
     
    Posted By: fostertomI think this calls for a highly bespoke mix n match plan, in which small details at various locations will be all-important and should determine the local solutions - and make sure those all link up into the best total scheme possible, and affordable. In other words, employ an architect with practical experience of different methods and of listed-standard buildings. A tall order but not imposible.

    Agreed, any decent whole-house solution will be very mix n’ match!
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