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General: WUFI Accreditation for Bldg Regs application

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      CommentAuthorfostertom
    • CommentTimeSep 26th 2023 edited
     
    Anyone any experience in getting Bldg Regs Part C (Resistance to Moisture - interstitial condensation etc) approval for constructions which rely on WUFI simulation rather than Glaser method? So far I've managed to avoid having to invoke WUFI, tho my favoured constuctions do come out of case-studies I ran when I had access to WUFI some years ago. But recently I've had Warmcel refusing to supply material to insulation installers without a Glaser-compliance certificate, and now Bldg Regs refusing to approve a whole scheme without similar. AFAIK e.g. tony and VikingHouse make professional use of constructions similar to mine.

    The recently revision to BS5250:2021 was intended to fix its shortcomings, with an excellent whole-building approach to all forms of moisture, in place of the simplistic/prescriptive approach of old BS5250:2002 and :2011. It allows (prefers) use of WUFI via BS 15026, explaining the limitations of the Glaser method via BS13788:2002. Yet I see that Bldg Regs Part C (still 2013 version) still requires compliance with BS5250:2002 (two versions out of date) i.e. use of Glaser method; BS 15026 isn't mentioned anywhere in the current Bldg Regs.

    So can WUFI be used at all in UK Bldg Regs? It obviously has been in useful use for years, so what's the route?

    And following that, what do I have to do to gain Accreditation to use my WUFI study in a Bldg Regs application? I've done the TGR 2-day course (twice actually) but that included no such certificate. I'm asking this elsewhere, but any idea here?
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      CommentAuthordjh
    • CommentTimeSep 26th 2023 edited
     
    I just did a quick skim reread of the regs. AFAICT the regs say nothing about particular standards, they simply say:

    "C2. The walls, floors and roof of the building shall adequately
    protect the building and people who use the building from
    harmful effects caused by:
    (a) ground moisture;
    (b) precipitation including wind-driven spray;
    (c) interstitial and surface condensation; and
    (d) spillage of water from or associated with sanitary
    fittings or fixed appliances."

    It's the approved guidance that mentions the standard and there it's just a statement that if you follow the standard you will meet the requirement. It doesn't forbid other ways of meeting the requirement.

    So there's no compulsion to meet the standard or to use it at all; you just have to demonstrate you've met the requirement. I would suggest performing a WUFI analysis and a Glaser analysis and writing up a short report that demonstrates the difference between them and why the WUFI one is more likely to be correct. I'm sure there must be published analyses of Glaser analyses producing incorrect results that you can refer to. You need to find a building inspector who's willing to accept science, or be prepared to appeal a refusal.

    edit to add: a reference that may be useful is https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/815953/R1_M10_Research_Summary.pdf

    and others found at https://www.gov.uk/government/publications/resistance-to-moisture-in-buildings

    "The Ministry of Housing, Communities and Local Government (MHCLG) commissioned PRP to carry out this research study, entitled Research into resistance to moisture in buildings. ....

    "Hygrothermal modelling should be used to assess moisture risk as advised in
    BS5250 6 . The simple Glaser method is only suitable for moisture closed and
    weathertight constructions, whereas dynamic hygrothermal simulation (using
    software such as WUFI or Delphin) should be used for moisture open
    constructions where wind driven rain or other moisture sources are present. ...."
    •  
      CommentAuthorfostertom
    • CommentTimeSep 26th 2023 edited
     
    Damn, you're right Dave, as so often. Part C 5.34 (walls) and 6.10 (roofs) both say
    "... will meet requirements if ... in accordance with ... BS 5250:2002 and 13788:2002".

    I was freaked by Bldg Insp Refusal saying "The design does not conform to the guidance of BS5250". Should have known better. Much relief - thanks.

    With that, just my last para above remains:
    Posted By: fostertomwhat do I have to do to gain Accreditation to use my WUFI study in a Bldg Regs application? I've done the TGR 2-day course (twice actually) but that included no such certificate. I'm asking this elsewhere, but any idea here?
  4.  
    Posted By: fostertomwhat do I have to do to gain Accreditation


    Are you sure there is formal accreditation? I'm sure when I looked into something similar for training 2D thermal bridging calculations (BS EN ISO 10211) it looked as though there was no accreditation body overseeing this.

    The onus appeared to be on the individual to demonstrate compliance with the British Standard through their output, but not through any form of qualifications or affiliation to a trade body.

    For what it's worth, TU Dublin are offering a series of online courses which I've been considering. One of these (TU5408) is in hygrothermal modelling and results in a certificate, plus it forms part of a wider MSc in Building Performance.

    It's run by Joe Little so will be similar to the one you did a few years ago, but in this case has the 'weight' of a university system behind it.

    https://www.tudublin.ie/study/professional-development/architecture/
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      CommentAuthorfostertom
    • CommentTimeSep 27th 2023 edited
     
    Thanks D_T, sounds like you are one who knows.
    But I wonder how it's poss to
    Posted By: Doubting_Thomasdemonstrate compliance with the British Standard through their output
    when all the Standard describes, I'd guess, is that software must accurately model a list of physics parameters, and users must competently input appropriate data and interpret the results.

    I expect there's a Certificate saying that the software complies, but the question is, how can any user demonstrate competence 'through their output' - who's to judge that the 'output' demonstrates competence? Surely competence has to be taken on trust, evidenced by some qualification or accreditation? Or I could have a go at impressing the Bldg Insp with my training and hours, don't know.
    •  
      CommentAuthordjh
    • CommentTimeSep 27th 2023
     
    Posted By: fostertomSurely competence has to be taken on trust
    No the competence of the submitter is assessed by the building control officer/inspector by inspecting their work. Which is open to the situation, apparently increasingly common, where the submitter knows more than the BCO.

    I could have a go at impressing the Bldg Insp with my training and hours, don't know.
    Exactly. Just write the report or whatever you need to submit in a form s/he expects and put in enough working and references to demonstrate the calculations are genuine.
    •  
      CommentAuthorfostertom
    • CommentTimeSep 28th 2023
     
    OK. sounds like a plan. Now all I have to do is get access to WUFI again - either E900 +VAT for a 1yr licence or E2900 + VAT for a 10yr or £900 for a 2day course in Nov incl 6wks free use of the software.

    Last time the issue came up, I contacted several firms who advertise that they use WUFI, to see if they'd do a case study or two for a fee, and they either just said no, or explained they only used it for their own internal projects, wouldn't take the risk of offering it as a consultancy!
    • CommentAuthorTimSmall
    • CommentTimeOct 16th 2023
     
    I ended up in a similar situation on my eternal retrofit. For the loft conversion roof, which we did about 10 years ago.

    At the time, I gave wufi calcs (moisture content graphs at key locations) along with a brief one paragraph summary. The local authority building inspect at the time said he was happy with it.

    The same building control submission included a rear extension, which we're only just now finishing up.

    A couple of weeks ago I requested a site visit for a newly constructed soakaway in the back garden. New building inspector arrived and said that they couldn't find any notes for anything to do with the loft conversion.

    I couldn't find the summary paragraph, but still had the graphs, so resubmitted them last week together with a 3 page essay.

    I'll let you know how I get on!
    • CommentAuthorcjard
    • CommentTimeOct 18th 2023
     
    Don't forget, the Approved Documents (Part xx) are NOT the Building Regulations. They are a ratified set of examples as to how one might construct a house so that it meets the requirements laid out in the BRs. The BRs are legalese that have much less to say about construction specifics and are essentially like "There shall be adequate means of ventilation provided for the people in the building". The relevant Approved Document then says "if you install these sized vents or this flow rated MVHR or blah blah blah (pages there of) then you will have met the requirement of the BR" - ultimately depends on your Building Inspector and whether they are satisfied you've met the requirements
    •  
      CommentAuthorfostertom
    • CommentTimeOct 18th 2023
     
    That's right, except for a tech thing like this, where they can't 'smell' whether it looks OK, they need proof. And the othr thing is the insulation suppliers (well, Warmcell anyway) now won't allow supply without that proof.

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