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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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    • CommentAuthorlineweight
    • CommentTimeNov 22nd 2023
     
    I last looked in depth at the options for internal wall insulation (for solid masonry walls) over ten years ago, and my conclusion was that much of the advice was contradictory and based on a rather incomplete state of knowledge.

    The worry of course is always about moisture and the big question is how important it is for the insulation to be vapour permeable to some extent.

    I've spent today trying to have a close look at what current advice/best practice seems to be. There's a bit more advice out there than there was, but there's still no conclusive answer on the importance of the buildup being moisture open. Certainly, the moisture open option seems to be considered the lower risk one.

    Anyway, my main question: can anyone give me a broad idea, of what the cost implications are, now? Compared to, say, going with 60mm PIR backed insulated plasterboard on dabs (which I'd consider the "bog standard" option) - does going for something like wood fibre mean adding a lot to the cost?

    I'm looking at cost of installation as well as materials here. Installation by a commercial contractor, rather than a DIY project.
    • CommentAuthorsgt_woulds
    • CommentTimeNov 23rd 2023
     
    This is a complicated subject and decisions shouldn’t be based on price alone.

    Upgrading the thermal envelope needs to take a holistic approach which accounts for the materials and breathability of the existing structure, cold bridges, architectural details, the disruption to the homeowner, the skill level and professionalism of the contractor, etc.

    There are plenty of examples where a failure to account for any one of these has caused issues, irrespective of the insulation materials.

    It is true to say that retrofit is less risky with a vapour-open approach using natural materials, but much of this has to do with the ability of the materials to absorb and release any moisture that builds up. Man-made insulations either can’t do that or can’t do it as well as a natural fibre so, for instance, a build-up of interstitial moisture will increase faster than with a breathable system. A ‘bad’ installation with natural materials will still cause issues – it will just take longer for those issues to become apparent.

    It is much harder to get a vapour-closed approach right – the SD value and detailing of the VCL needs to be perfect for the situation. You also do not want any gaps between the insulation and the wall surface as this increases the risk of condensation forming.

    In my opinion, this is impossible to achieve with the insulation pre-bonded to plasterboards, and should always be built up in individual layers instead. This takes time, expertise, and attention to detail, which a lot of tradesmen unfortunately do not have.

    We often get calls from people who have had a poorly installed vapour closed upgrade and looking to replace the insulation with our woodfibre boards to ameliorate the symptoms. Often this is not due to the materials, or the vapour closed approach, but lack of attention to other areas. The holistic approach I was talking about earlier.

    Internal wall insulation will move the dew point within the construction, and this may cause issues with the existing structure. Standard U-value calculations will not correctly account for the sorption properties of natural fibres, nor their ability to pass on liquid water through capillary action.

    The external brickwork and pointing will need to be assessed and repaired if in poor order to reduce the passage of moisture to what will become a colder wall. I’m constantly amazed at how often this isn’t done. People try to treat the symptoms of dampness and mould, not the cause.

    For IWI a WUFI calculation is a useful check - this purely considers moisture issues and how the various elements of the building fabric will deal with the moisture volumes based on site-specific conditions.

    It is important to note that there is a balancing act between achieving the best U-value, the increased risks of moisture in the wall, the loss of space, and the cost. The cost should always be the last one on that list.

    In basic terms, a natural insulation will cost more than a plastic or glass one. However, this is often offset by not requiring additional VCLs and additional labour time for detailing which speeds up installation. Overall costs can be the same, or at least not vastly more.

    It is more important to worry about the competency, (and honesty) of the installation than the bottom line cost – a poor install might end up costing more in the future to put right.

    The ASBP has a webinar on IWI which covers most of these topics:
    https://asbp.org.uk/webinar-recording/rethinking-iwi-with-natural-fibre-insulation
    • CommentAuthorlineweight
    • CommentTimeNov 23rd 2023
     
    I agree with all that.

    But if I'm proposing to someone that we go with a vapour open approach, they are going to ask me what the cost implications are, and I'd like to be able to give a realistic answer.

    If it puts the project outside of their budget, then defaulting to vapour closed is not the only option - it might be that the consequent decision is not to do it at all, or to postpone it until funds are available.

    If the truth is that the cost is not that different as long as we're talking about a properly done installation in either case - rather than comparing apples and oranges - then I'd like to be able to tell them that confidently.
    • CommentAuthorlineweight
    • CommentTimeNov 23rd 2023
     
    Another question ... are there any vapour open systems that have a BBA certificate?
    •  
      CommentAuthordjh
    • CommentTimeNov 23rd 2023
     
    Posted By: lineweightAnother question ... are there any vapour open systems that have a BBA certificate?
    I think there are lots, according to mr google. Do you have anything specific in mind?

    Also it used to be the case that an equivalent European approval was acceptable, which was very handy when we built. I don't know if that is still the case?
    • CommentAuthorsgt_woulds
    • CommentTimeNov 23rd 2023
     
    BBA certification is voluntary rather than mandatory.

    We do not hold BBA certification on our own woodfibre insulation boards; the boards are manufactured to the relevant EN standards and CE marked accordingly.

    In addition, all of our products have installation detailing available and third-party certified EPDs which is not the case for all manufacturers yet.

    Regulation 7 (1) states CE marking and the appropriate Declaration of Performance can be used as a way of establishing the suitability of a product for its intended use.

    Additional national or international technical specifications are referenced in Section 1.14 and Independent certification schemes in Section 1.15, but these are not mandatory - it is explicitly stated that they ‘may be in addition to, but not conflict with, CE marking’.

    Given the issues surrounding UKCA, I don't see that changing soon. But given the economic kamikaze tactics of our elected representatives, I'd never say never.
    • CommentAuthorlineweight
    • CommentTimeNov 23rd 2023
     
    Just three that I've looked at so far

    https://www.ecologicalbuildingsystems.com/solutions/renovation-retrofit
    -doesn't have BBA

    https://www.acaraconcepts.com/wood-fibre-insulation/wood-fibre-products/
    - although "pavadry" is listed here as having one, it turns out it's expired

    https://www.steico.com/en/products/etics/steicointernal-render-board-for-internal-insulation/steicointernal
    - doesn't seem to have one.

    You're right that European equivalents might be acceptable for many purposes. I find the presence of a UK certification reassuring when I'm looking at something that will be installed on UK housing stock in a UK construction industry context.
    • CommentAuthorlineweight
    • CommentTimeNov 23rd 2023 edited
     
    Posted By: sgt_wouldsour own woodfibre insulation boards;


    Which ones are these?
    •  
      CommentAuthordjh
    • CommentTimeNov 23rd 2023
     
    Posted By: lineweightI find the presence of a UK certification reassuring when I'm looking at something that will be installed on UK housing stock in a UK construction industry context.
    Welcome to the real world :bigsmile:
    • CommentAuthorlineweight
    • CommentTimeNov 23rd 2023
     
    As I see it the questions I'm asking in this thread are totally related to the "real world".

    Maybe I should clarify that in this case I'm looking at things from the perspective of specifier. I have done a fairly major IWI project on a DIY basis and the decision making process in that scenario can be rather different.

    To explain why a BBA certificate is useful to a specifier - part of it is about covering your tracks in demonstrating you've taken reasonable steps when making choices on someone else's behalf. BBA certs don't just tell you that something has been manufactured according to relevant standards, they also tell you what are judged to be appropriate uses, installation methods and so on. Often this is subtly but significantly different from what the manufacturer says or implies.

    To me the existence of a BBA certificate is also some signal that the product is not obscure in the UK context. This can be rather important if you are worried about scaring off contractors with things they have never heard of or will find hard to get hold of. This is a very "real world" concern.

    Of course a BBA is not the be all and end all when looking at options. But certainly a nice-to-have.
    • CommentAuthorlineweight
    • CommentTimeNov 23rd 2023
     
    Posted By: sgt_woulds
    In addition, all of our products have installation detailing available


    I should say, this also gets many bonus points on the reassurance scale. Along with responsive technical support.
    •  
      CommentAuthordjh
    • CommentTimeNov 23rd 2023
     
    • CommentAuthorlineweight
    • CommentTimeNov 23rd 2023
     
    Yes I know, I followed the Grenfell enquiry in some detail. The BBA system is not perfect just like all the other checks abd systems that failed throughout every aspect of that project. Not sure what your point is exactly.
    • CommentAuthorsgt_woulds
    • CommentTimeNov 24th 2023
     
    People do get hung up on BBA and most BCO's, Architects, Quantity Surveyors, etc., don't really know what a BBA entails or that it is not mandatory.

    My earlier explanation was cut and pasted from a standard e-mail response that I send out on a nearly daily basis.

    All natural insulations are obscure in the UK context. That won't change until the DIY boxes start selling it off the shelf and promoting it. Not to mention education and policy change to promote its use over 'traditional' materials. This has been done successfully in France and to some extent Italy which are the world's biggest markets for woodfibre right now. Can you see our current rulers taking note of successes in foreign lands?

    The sad truth is that the UK market for insulation in general, and natural insulations in particular, is absolutely tiny in the grand scheme of things. Paying for BBA does not make economic sense at the moment. Especially when it achieves nothing above what EU technical approval does - other than add a typically British layer of red tape, delay and cost.

    I do understand the 'warm tummy' feeling a BBA gives to the end users, and I also understand that using CE products requires a bit more effort in explanation from specifiers, but it really shouldn't be a stumbling block.
    • CommentAuthorsgt_woulds
    • CommentTimeNov 24th 2023
     
    "To me the existence of a BBA certificate is also some signal that the product is not obscure in the UK context. This can be rather important if you are worried about scaring off contractors with things they have never heard of or will find hard to get hold of"

    Have you tried to buy Rockwool recently? In Brexit Britain nothing is easy to get hold of.

    I specified a number of products for my extension build that proved to be extremely difficult to get hold of, despite them all being 'in-stock'. Lots of wholesalers advertise products, will happily take your money, and then phone you the next day to say there will be a six-week delay in delivery!

    Then when it does arrive you'll find it has been substituted with an 'equivalent'...


    Strangely, the payment comes out of your bank account instantly, but it takes 4 - 8 weeks to refund.
    • CommentAuthorMike1
    • CommentTimeNov 24th 2023
     
    Posted By: sgt_wouldsmost BCO's, Architects, Quantity Surveyors, etc., don't really know what a BBA entails or that it is not mandatory.
    I'm sure a lot of small builders don't have a clue, but I'd be very surprised if more than a handful of qualified BCOs, Architects & Quantity Surveyors don't.
    • CommentAuthorsgt_woulds
    • CommentTimeNov 29th 2023
     
    Standard enquiry - at least once a day: 'BCO wants to see the BBA certification'

    At least 2 enquiries per week from architects who have agreed with client for BBA certified product.

    Don't have as many QS questions, but they do come in sometimes.

    My views on the majority of architects are probably best not repeated here - let's just say the good ones are notable by their exception to the rule. :devil:

    Most BCOs are too busy and not motivated to learn new things. New products? Amendments to long-standing regulations? Modern methods of construction? Better do your homework well and expect a lot of obstinacy...

    Builders don't care about certificates. They just want clear instructions and enough confidence in the product that they won't have to rectify future issues at their expense.

    BBA, like MCS, is mostly about making money for people who don't do any of the actual work or research.
    • CommentAuthorlineweight
    • CommentTimeNov 29th 2023
     
    If you're looking at a building product or system though, and wondering - is this fit for the purpose I want it for, how does one actually answer that question?

    There's no easy route to a definitive answer, so you have to attack it from as many angles as are available. You still won't usually get a definitive answer, but you'll have done the best you reasonably can.

    Asking if there's a BBA certificate is just one of the things you can do as part of that process. If an architect or surveyor asks whether there's a BBA certificate, that doesn't necessarily mean they think it's mandatory, or that it's the only check that they are doing.
    • CommentAuthorsgt_woulds
    • CommentTimeNov 29th 2023
     
    It's true to say that once we point out the regulations, the architects are normally satisfied, but they still have to convince their customers and BCO who have been gaslit into thinking a certificate is required. It is a shame - and a surprise - that we have to point this out to them in the first place. Given the cost and length of their education and the amount they charge for their expertise, this is one of many areas where I - as a layman - am amazed by their lack of knowledge.

    In a perfect world, checking the product certification would be just one step in a chain of due diligence that would result in compliance with building regs and product installation specifications. Unfortunately - all too often - having the certificate on file seems to be where accountability stops.
    • CommentAuthorlineweight
    • CommentTimeNov 29th 2023
     
    Posted By: sgt_wouldsIt's true to say that once we point out the regulations, the architects are normally satisfied, but they still have to convince their customers and BCO who have been gaslit into thinking a certificate is required. It is a shame - and a surprise - that we have to point this out to them in the first place. Given the cost and length of their education and the amount they charge for their expertise, this is one of many areas where I - as a layman - am amazed by their lack of knowledge.

    In a perfect world, checking the product certification would be just one step in a chain of due diligence that would result in compliance with building regs and product installation specifications. Unfortunately - all too often - having the certificate on file seems to be where accountability stops.


    I'm not really clear about what exactly it is that you think that architects in general should be doing, compared to what you observe them doing.

    The fact is, there is no real failsafe "chain of due diligence" that guarantees compliance with building regulations. There is no set procedure that an architect (or anyone else) can go through that tells them absolutely definitively that what they are designing and specifying will be OK. Much of it relies on subjective judgement and obtaining opinion from people with practical experience.

    The architect's life would be much easier and less stressful if there were some check-box procedure that led with certainty to the right decision each time.
    • CommentAuthorsgt_woulds
    • CommentTimeNov 29th 2023
     
    My observations are based more on their lack of up-to-date knowledge on certain aspects of building regulations, (which applies equally to BCOs).

    I'm not sure if this is due to the training they receive or the lack of oversight once qualified. In my experience, a decent electrician will know the electrical regulations inside out, even if there is room for debate about the methods of meeting those regulations. They are regularly tested on amendments and additions. Sauce for the goose?

    I fully agree that there should be a process in place for due diligence, one that is assessed and approved by an independent body in consultation with the affected parties and not just imposed. I'm nervous about the term 'check-box' because we know what that implies. And the disasters it can lead to.

    Companies that import timber-based products have to set up due diligence procedures in order to meet UKTA / EUDR regulations amongst other things. These are assessed by an independent body such as the Soil Association, which ensures the steps in the process lead to a logical conclusion. Then they are tested yearly to make sure this system is complied with. No system is failsafe, but a regulated system would go some way to preventing another Grenfell.

    The joy of the building regulations is that there isn't a prescribed way of meeting them. Otherwise, every building would be the same and we'd never see any innovation or improvement. But that does require investigation, and expert advice as you say.

    We don't need to add to that process by requiring additional certification when an equivalent EU version has already been achieved. If the product is designed as part of a system, if that system has been tested and installation details are available, and if the products are installed as per the system requirements then there should be no room for arguments about meeting building regulations.
    • CommentAuthorlineweight
    • CommentTimeNov 29th 2023
     
    When you say the equivalent EU version - do you mean the CE mark and associated DoP?
    • CommentAuthorsgt_woulds
    • CommentTimeDec 15th 2023
     
    That and EN standards, EPD, and independent testing such as from the IBR [Institut für Baubiologie Rosenheim GmbH] etc, etc. all of which have been challenged in recent years with people demanding UK-specific versions.

    It has always been the case that whenever a certification scheme is set up, a new one will arrive 5 minutes later to take their share of the silver - but you always had choice and equivalency so you could push back. Now there is a jingoistic slant that does nothing to improve standards but puts obstacles in the way of sales.
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