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Part L consultation and multifoils

by mel starrs on June 24, 2008

in Part L

I’ve read through the (non-technical) consultation which is out for Part L – comments to be back by 9 September.

The only item which piqued my interest was the clarification regarding multifoils.

3.1 BR 443 “Conventions for U-value calculations” sets out test methods and
calculation procedures for determining the thermal performance of building
elements that are considered appropriate for demonstrating compliance
with Part L of the Building Regulations. These test methods and calculation
procedures are based on the British and International standards that were
previously listed in earlier versions of the Approved Documents L.
3.2 In a judgment given in 2007, the High Court concluded that the Department
had not properly notified the European Commission, as required by the
Technical Standards Directive (98/34/EC), of the specific provisions contained
in paragraph 3.10.2 of BR 443 (March 2006 edition) for measuring the
thermal performance of multi-foil insulation products. Paragraph 3.10.2 was
declared unenforceable and remains so unless and until the correct notification
procedures under the Technical Standards Directive are completed.
3.3 That judgment did not affect other parts of BR 443 or the Approved
Documents L, and so the references in the Approved Documents L to BR 443
have continued to form part of the approved guidance on how compliance
with building regulations may be shown. Thus the general guidance in BR
443 for measuring thermal performance continues to apply to all building
elements, including multi-foil insulation products. This means that it remains
the case that only test results obtained from “hot-box” tests or tests that have
been agreed at a European level, such as those forming part of an agreed
European Technical Approval (ETA), carry a statutory presumption that they are
correct. However, the consequence of the judgment is that there is currently no
approved guidance which relates specifically to the measurement of thermal
performance of multi-foil products.

I’ll admit, this would not normally have been on my radar, except for the previous posts here, here and here from Mark Brinkley. Although the wording has now been cleared up, the performance of multifoils has still not been confirmed. It appears that paragraph 3.10.2 will eventually be reinstated:

3.5 The Department’s present view is that the appropriate methods for measuring
the thermal performance of materials and products are the hot-box test (which
is a British Standard test based on Standardised European Norms), or tests that
have been agreed at a European level. BR 443, including paragraph 3.10.2,
requires that measurement of thermal performance should be carried out using
such agreed tests. For this reason, the Department’s view is that the references
in the Approved Documents to BR 443, including paragraph 3.10.2, are
appropriate. It is for this reason that those references are retained in the draft
Approved Documents L that are the subject of this consultation.
3.6 This position has previously been set out in Communities and Local
Government Circular 06/2007, issued on 7 December 2007 as part of the
Department’s compliance with the judgment of the High Court.

I expect we’ll be hearing more from multifoil manufacturers between now and September then.

3.9 The Department is currently of the view, based both on international
scientific opinion and on scientific evidence commissioned and published by
it, that comparative testing does not provide accurate indications of thermal
performance.
3.10 The Department is however keen to know your views on this matter and
on whether generally the references to BR 443 as set out in the proposed
Approved Documents should be retained in the Approved Documents, and the
reasons for those views. If your views are that they should not be retained, the
Department would like to know your views on what should replace them.

The rest of the alterations are substantially cosmetic, but with a technical review due in 2010, and the last version 2 years old, we’ll have 3 copies of the regs within 2 or 3 years.

I’m in two minds about this.  On the one hand, it is better to have the entire document updated rather than having an errata addendum (such as the recent Code for Sustainable Homes which has the April 2008 Technical Guidance (pdf, 302 pp.) and the Addendum published 4 June 2008 (pdf, 16 pp), but on the other, with only cosmetic changes, it seems a waste of paper and a potential source of confusion.

  • 534nm

    The last loft conversion I built was after the LABC ruling on multifoils. But I got Regs approval before the ruling and was allowed to continue with Actis.

    The very first loft I did we used Celotex and I vowed never to use it again. Regardless of the debate about multifoils, cutting a rigid foam board into existing rafters is not fun – it’s easier to fix a multifoil to the u/s of the rafters.

    As Mark Brinkley found out, I too found that MLM were prepared to approve a subsequent loft designs using multifoils.

    Somebody needs to sort this out one way or the other because the smaller loft conversions really need a multifoil to maximise the headroom of the finished conversion.

    Only, in my experience MLM were more expensive than local authority and it meant persuading the client to pay more for the Regs approval so as to get more headroom.

  • 534nm

    The last loft conversion I built was after the LABC ruling on multifoils. But I got Regs approval before the ruling and was allowed to continue with Actis.

    The very first loft I did we used Celotex and I vowed never to use it again. Regardless of the debate about multifoils, cutting a rigid foam board into existing rafters is not fun – it’s easier to fix a multifoil to the u/s of the rafters.

    As Mark Brinkley found out, I too found that MLM were prepared to approve a subsequent loft designs using multifoils.

    Somebody needs to sort this out one way or the other because the smaller loft conversions really need a multifoil to maximise the headroom of the finished conversion.

    Only, in my experience MLM were more expensive than local authority and it meant persuading the client to pay more for the Regs approval so as to get more headroom.