The new British Standard for conservation, BS7913 'Guide to the conservation of historic buildings', states that the objective of building conservation is to secure the protection of built heritage, in the long-term interest of society.
 
BS7913 states:
5.3.2 Materials
The correct choice of materials for conservation works is important for historic buildings. Where possible, existing materials should be investigated and tested so that good performance and aesthetic matches can be achieved. In cases where the existing material source is not available, reuse of suitable materials from salvage might give better results than newly formed materials. However sources should be verified to ensure this does not cause degradation of other historic buildings and to ensure that repairs are identifiable. In cases where materials are vulnerable to theft or damage or where previous details have failed, substitute materials might be appropriate.
Protective measures should be taken for high value materials in areas where there is a high risk of theft or vandalism.
This clause would be better if 'might' was changed to 'will' and some pointed reasons were added, along these lines:
Reuse of suitable materials from salvage will give better results than newly formed materials, will save historic resources from landfill or crushing or burning, will be less damaging to the environment, will use less energy, will create fewer carbon emissions and will reduce global warming. It will also create crafts skills in repairing and restoring old materials. This would also make the clause comply with EU and UK government policy on reuse.
 
The drafting committee consisted of representatives of the Chartered Institute of Building, English Heritage, Historic Scotland, Institute of Historic Building Conservation, Institution of Civil Engineers, International Council on Monuments and Sites, National Trust, Royal Institution of Chartered Surveyors, Cadw - Welsh Gogerments historic enviroment service (sic).
 
John Edwards, Assistant Director, Properties in Care at Cadw, and IHBC member, who led the update of BS 7913, said (on the IHBC blog), "After three years and a consultation that brought about many good, but often conflicting views, I am pleased to see that this is now published for use by the specialist sector and mainstream property and construction industry. British Standards are commonly referred to by the mainstream, most of whom may not even know that conservation principles published by English Heritage, Cadw and others even exist. As such, the British Standard is a very important way of embedding awareness of conservation practice right at the heart of mainstream operations."
 
In 2008, English Heritage produced its own conservation principles, which stated:

98. The reuse of sound materials derived from the place being repaired or altered is traditional practice and contributes to the sustainable use of energy and material resources. Mixing old and new materials in exposed situations, however, may be inadvisable. Maintaining demand for new traditional and local materials will also stimulate their continued or renewed production, and help to ensure a sustainable supply and the craft skills to utilise it.
99. The reuse of sound traditional materials recovered from alteration and demolition elsewhere can also contribute to sustainability, provided they are not derived from degrading other significant places primarily because of the value of their materials.

Cadw published its conservation principles in 2011:

38  As with repair, the use in new work of materials and techniques proven by experience to be compatible with existing fabric, including recycled material from an appropriate source, tends to bring a low risk of failure. Work which touches existing fabric lightly, or stands apart from it, brings a greater opportunity for innovation and reversibility.

The clauses above from Cadw and English Heritage appear to have been merged into BS7913.
 
The BS7913 5.3.2 materials reuse clause also states: 'However sources should be verified to ensure this does not cause degradation of other historic buildings and to ensure that repairs are identifiable'.
 
The verification of sources does make sense, but this should apply to all materials used in building, both new and old. For example, pollution from the manufacture of new building materials used in conservation and the rise of sea levels caused by carbon emissions and global warming, affect many 'other historic old buildings', both within and outside the UK.
 
Clause 5.3.1 states that 'Building materials and products should be sourced and procured in a sustainable manner' but, unlike the reuse clause, it does not qualify how to do this.
 
So BS 7913 appears skewed towards favouring new materials over reclaimed ones even though government policy recommends reuse wherever possible.
 
[Story ends
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Rant Alert!
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The introduction to BS 7913 states (in part):
The decision to conserve historic buildings can be justified on social, cultural, economic and environmental grounds … Conflicting pressures often need to be balanced to assist good decision making. Good conservation depends on a sound research evidence base and the use of competent advisors and contractors.
 
When people first began to build they built for themselves, without the aid of specialist builders. What they built was, in the precise meaning of the term, 'vernacular' (i.e. native or of the country). The system by which the people of a particular place built was developed empirically over many generations, closely integrated with geology, climate, land use and seasonal patterns.
 
Even the more refined ways of building were subject to the same local and vernacular influences. This is the basis of what can be termed the architectural geography of the United Kingdom. The local and vernacular materials and construction of buildings contribute to a sense of place.
 
The aim of builders throughout the ages has been to produce buildings which were as well-built as they could be with the materials and skills available. These served the needs of the people who used and occupied them, and their form and decoration were refined as a means of cultural expression. In the first century BCE the Roman architect Vitruvius defined the three essential attributes of architecture as 'commodity, firmness and delight'.
 
The integration and balancing of function, sound construction, economics and aesthetics remains the objective of all architectural activity. Buildings of all types and periods contain information about the way in which people lived, worked and worshipped, how they built and how they thought and wished to present their own culture and their spiritual values.
The introduction gives an insular conservationist view that neglects to mention that Stonehenge was built from alien not local stone, that the Romans brought old parts of buildings with them to reuse in Britain, that timber frames were often built from reclaimed ships or other repurposed and not local timber, that Uppark was built with reclaimed oak joists, that the Georgians ported in materials and features from grand touring the ancient world, that the Victorians continued and added more exotic materials from the British Empire and robbed palaces in China and India, that in the 1930s McAlpines reused the Georgian bricks from the old Dorchester House in Park Lane to build council estates in north London, and so on and on.
 
It also overlooks the many British buildings that were funded with the profits of slave and child labour, and built with materials that were not fairly traded, and often simply stolen. Some of the heroes of the conservation world, such as the revered William Morris, have dirty secrets which tend to be overlooked. And it does not care to state that many, if not most, of the building skills Britain had were not invented here, but learned from, among others, Italian stuccadori, French glassworkers, Dutch brick and tile makers and Huguenot sculptors.
 
Neither Salvo, nor I suspect the salvage trade, were consulted about BS7913, possibly because of trenchant views when it comes to the role of conservation policy in the wasteful destruction of hundreds of millions of tonnes of sound historic building materials from demolition and refurbishment.
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Rant over!
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