British and European Standards for Heritage and Conservation

Tim Yates

The wide variation in the standards and codes of practice which affect business in Europe are seen by
the Council of Europe as a barrier to trade between member states. Existing British Standards and
those of other countries are therefore slowly being replaced by new European-wide standards.

 

   
  Is it safe? Is it strong enough? Will it last? These are the issues addressed by European Standards. Standardising thatching materials might be a useful means of improving quality of some materials, although the question of whether a material is appropriate is another issue.  

If you search on the British Standards website for standards and codes of practice related to conservation then, once the references to energy are discounted, there are, as expected, few relevant ‘hits’. At a national level there is guidance on good practice – for example in the UK there is the code of practice for the cleaning and surface repair of buildings (BS8221 Parts 1 and 2) as well as BS7913 which deals with the conservation of buildings in general. With more careful searching it is possible to find a considerable number that may have some bearing on building conservation – for example those relating to the testing of natural stone or the specification of mortars – but few, if any of these are written with conservation in mind.

The original purpose of standards was to ensure that fixtures and fittings were of a consistent size and quality but over the past 100 years the purpose has shifted towards providing a minimum quality and making sure that methods and materials reflect good practice. Standards and codes of practice allow specifications to be written in a clear and concise way. They can also be used to support accreditation schemes for conservators and building conservation craftsmen.

There are currently a wide range of test methods established by CEN (Conseil Européen pour la Normalisation, the European standards authority) and others such as ASTM (the American Society for Testing and Materials – one of the US standards organisations) which are relevant to the testing of individual materials (for example stone or concrete) or their conservation treatment (for example UV testing of coatings). There are also tests drafted by international groups such as RILEM (the International Union of Laboratories and Experts in Construction Materials, Systems and Structures – see the inset box further down this page) on the characterisation of materials, for example historic mortars. However, there are far fewer standards for the assessment of combinations of treatments (for example cleaning and consolidation) and composite units (for example masonry walls). The plethora of existing test methods makes it essential that any new committee accepts these and restricts its activity to producing methodologies for the application of existing tests to heritage materials and, if possible, providing some guidance on the interpretation of the results that are obtained.

EUROPEAN STANDARDS AND CONSTRUCTION PRODUCTS DIRECTIVE

European standards are a key part of the Construction Products Directive which was conceived as a way of breaking down artificial barriers to trade and so produce an ‘open market’ throughout the EU countries. However, it has become clear that European standards have the potential to raise additional barriers if they are formulated in any way that favours one country or one sector of the industry. There is also a danger that the standards can overprotect the consumer at the expense of the producer.

Like all European standards, those for construction materials have three parts; an agreed and harmonised set of specifications and test methods, an agreed system which sets out who is responsible for carrying out the tests and assessments, and a method for evaluating (or checking) that everything is being done correctly.

In the case of natural stone and some other products, the manufacturer is able to declare his results but still requires an ‘agent’ – usually an independent laboratory approved by CEN – to affix the ‘CE’ mark. The CE mark, which is displayed on the product or its packaging, shows that the product has been tested to an agreed specification and allows it to be placed on the market. In many countries once the relevant specifications are in place it becomes a legal requirement to apply the CE mark to qualifying products.

The CE mark is not a quality mark since it demonstrates a compliance with a minimum requirement, although it still seems to be mistaken for one. It must be remembered that the driving force behind the European standards is the need to fulfil the demand from the EU (via CEN) for CE products within certain ‘product family groups’ and that there has been no requirement to raise standards of work or even the quality of individual products. The three key questions which should be answered by the European standards are:

  • Is it strong enough?
  • Is it safe?
  • Will it last?

These three questions are equally relevant to building conservation – particularly ‘will it last’ – but they need to be considered against the all-important question: is it appropriate to the existing building or structure? It is this consideration that sets conservation apart from the ordinary run-of-the-mill CE marked products.

The whole process of drafting and agreeing European standards seems to have taken a very long time – more than 10 years for natural stone and masonry products. But now many of the test methods have been approved and issued as European standards by BSI in the UK – these are usually called ‘BSENs’. In addition, the first of the specifications, for example those for paving, setts and kerbs, have been accepted and we are now in the official ‘transition’ period prior to the withdrawal of national and other standards which have been superseded by the new European standards. Occasionally, the slow progress of European standards results in a national standards organisation asking CEN for permission to develop its own national documents and this is usually accepted provided that the national documents will not conflict with European ones.

 

THE PRINCIPAL STANDARDS ORGANISATIONS

ASTM – American Society for Testing and Materials is one of the main standards organisations for the US, Canada and the Pacific Rim countries.

BRE – Building Research Establishment is the UK’s leading centre of independent expertise on building and construction and the prevention and control of fire. This expertise is available to all in construction and associated industries, from multi-national companies and government departments to individual designers, builders and building owners and users. BRE provides independent and authoritative advice relevant to every stage of the life cycle of a structure from design, through construction and use, to demolition and recycling.

CEN – Conseil Européen pour la Normalisation is the organisation set up by the EU to implement the Construction Products Directive. CEN’s mission is to promote voluntary technical harmonisation in Europe in conjunction with worldwide bodies and its partners in Europe. It is envisaged that harmonisation will reduce trade barriers, promote safety, allow interoperability of products, systems and services, and promote common technical understanding.

RILEM – Réunion Internationale des Laboratoires d’Essais et de recherche sur les Matériaux et les constructions – the International Union of Laboratories and Experts in Construction Materials, Systems and Structures. This organisation is based in Paris and provides a platform through which interested groups can develop ‘standards’ in areas of mutual interest.

 

PROPOSED EUROPEAN STANDARDS FOR HERITAGE AND CONSERVATION

A proposal to form a CEN Technical Committee to draft documents related to 'Standardisation in the field of conservation of Cultural Heritage' was put forward by UNI (the Italian National Standards Organisation). This proposal has been accepted by CEN and the committee is preparing to start work as Technical Committee 346.

The Scope and Introduction of the committee seem to be straightforward and to be based on earlier work undertaken by UNESCO. The Scope describes the very wide range of applications covered by the term ‘artefact’ – from ethnographic objects to buildings. The Scope concludes with an outline of five areas which the committee believes standardisation activity on the conservation of cultural heritage should deal with. These are:

1. Terminology relevant to movable and immovable artefacts, and to the conservation of the artefacts and the material constituting the artefacts

2. Guidelines for a methodological approach to the knowledge of the artefacts and of the materials constituting the artefacts, of the deterioration processes, and of preservation/conservation work

3. Test and analysis methods for the diagnosis and for the characterisation of the artefacts

4. Tests and analysis methods for the evaluation of the performance of conservation products

5. Test and analysis methods for the evaluation of indoor conservation conditions – particularly transport, packaging and exhibition environments.

It seems clear that the proposal is potentially very wide ranging and that it is influenced by ‘political’ factors – particularly at a European level. Its overall vision is well illustrated by a quotation from a European Parliament document (STOA 2001) that standards are required 'to provide vision, guidance and guidelines for "best practice" at a European level, such as scientifically-based protocols for validating conservation work on monuments and archaeological remains'.

Many countries provide some guidance – usually focused to their own traditions and environments but it is difficult to transfer prescriptive methods from one country to another, and even more difficult to gain agreement from 19 countries.

THOUGHTS FOR THE FUTURE

With a general trend towards more European standards, it seems only sensible that building conservation also should develop standards and codes of practice. However, there is always a risk of standards being developed internationally that do not reflect local (or regional) good practice and which may also stifle innovation and the development of new skills. Therefore, the ‘industry’ must make sure that its views are represented on both national and international standards committees.

This article is reproduced from The Building Conservation Directory, 2003

Author

TIM YATES is the director of the Centre for Whole Life Construction and Conservation at the Building Research Establishment. He has expertise on the weathering of building materials, effect of salt on natural stone and mortar, long term performance of pavements and floors, codes and standards for paving and flooring materials, inspection and assessment of historic buildings and structures, protection and conservation of natural stone.

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