Pete recently did an interview on BBC Radio 4 - You and Yours - which investigated a case history of failed cavity wall insulation.
Part L1B of the 2010 Building Regs:
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/697629/L1B_secure-1.pdf
The relevant paras are 3.6 to 3.13 (also reproduced in Part L2B). The most significant addition here is the recognition of “buildings of traditional construction with permeable fabric that both absorbs and readily allows the evaporation of moisture” (3.8c). Whilst not ‘exempt’, these fall under a category where “special considerations may apply”, i.e. “The work should not prejudice the character of the host building or increase the risk of long-term deterioration of the building fabric or fittings” (3.9)
These regulations, according to a good friend who is a Conservation Officer, are two major steps forward: a) there is recognition that traditional construction and longevity are important, as something additional to the more esoteric notions of historic character and appearance, and..
b) this does not only apply to designated heritage assets.
There are quite a few hurdles though: It is still only a case of ‘special circumstances may apply’; so your bog standard architect/builder/building control officer, can quite happily carry on as before. My experience so far is that it is only where an architect/builder is already in the conservation know that this comes into play, and it appears to be down to them to prove their case to Building Control rather than the other way around. That said, where Building Control are asked to consider an exemption, they are usually quite happy with a line or two from their conservation officer to confirm it accords with the LB Act etc.
The Regs state that English Heritage guidance should be taken into account (and there is now a good breadth of guidance from them), but the only specialist advisor referred to is the local authority conservation officer. Two worries here. As the recent LASR report showed, Conservation Officer numbers have fallen by 21.8% over the past 5 years and most services are already overstretched; if the provision were universally put into practice the additional workload would be phenomenal (EH have a figure of around 20% of the building stock being pre-1919, and another 20% 1920-1939). My friend, the Conservation Officer, as an example, is already banned from operating outside the realms of designated heritage assets, or indeed outside of ‘planning’. Then there is the fact that however much a conservation officer may know, they are not qualified to give structural advice over and above that of a structural engineer. Under LBC applications my friend has had many pointless arguments with structural engineers - at the end of the day, their qualifications have simply trumped hers for structural issues. (EH, incidentally, has only one Structural Engineer to cover the entire country. Not much use on a day to day basis).
But, the introduction of the 3.8c category of building into the Building Regs does enormously strengthen the argument for traditional buildings to be given much higher priority throughout the building industry and education, and not just seen as a specialist and slightly cranky sideline.
My friend obviously can't be named, as a serving CO, but has another really good suggestion here:
Example of how to shut Building Control up, if its useful : “I confirm that the reinstatement of the timber-framed wall with brick infill, and single-glazed softwood casements, have been approved under Listed Building Consent 11/15068/LBC and are considered appropriate to retain and restore the special historic and architectural interest of the listed building in accordance with the Planning (Listed Buildings and Conservation Areas) Act 1990, British Standard BS 7913:1998, and the Building Regulations 2000 Part L 1B para 3.11. Likewise the internal lime plaster will reproduce historic finishes and ensure the building is maintained as a breathable structure in accordance with Part L 1B para 3.12.”) (They like regulations).
I have to say that there ARE some fantastic people out there, and this CO is brilliant. She can upset the client easily enough - but all of a sudden they realise she's prompting them for the information that she needs to be able to approve the application. I dont think this is unusual - people very often jump to the conclusion a Conservation Officer is being difficult. They're usually not - they just want to do things the right way - if you listen carefully, they are just trying to prompt you as to what to say, and how to make an application that will succeed. They became a CO for a reason usually - because they like old buildings!