Eurocode 6: Design of Masonry Structures
   
The Construction Products Directive and the Development of European Standards for Masonry

Introduction  
A key element of European legislation supporting the elimination of barriers to trade between the Member States of the European community (EC) is the Construction Products Directive (CPD)(1).  This was adopted by the Council of Ministers in 1988 and was the third 'New Approach' Directive to be approved.  This is a reflection on the importance of building and civil engineering within the EC as the largest sectors of the economy.  The Directive was given legal status in the UK in 1991 with the implementation of the Construction Products Regulations. In 1994 the CPD was amended by the “CE marking” Directive(2) which was implemented in the UK by the Construction Products (Amendment) Regulations which came into force on the 1st January 1995. The CPD is unique amongst the New Approach Directives in that the essential requirements do not apply directly to products until they are incorporated in works.

The Construction Products Directive
The 27 clauses of the Directive cover all aspects of the requirements and methods of compliance.  Essentially, compliance is through European Technical Specifications which, for construction, are Standards developed by CEN(European Committee for Standardisation, which has representation from each National Standards Body e.g. BSI) and European Technical Approvals (ETAs) from the European Organisation for Technical Approvals (EOTA).

The CPD identifies six essential requirements for finished works, and these are:
·        Mechanical resistance and stability

·        Safety in case of fi

·      Hygiene, health and the environment

·        Safety in use

·        Protection against noise

·    Energy economy and heat retention

Six interpretative documents link the essential requirements to more specific product requirements and explain what the technical specifications need to address in order to satisfy the requirements of the CPD.

The Contents of a European Standard

Standards in Europe usually contain two types of requirement, namely:

  ·        requirements which must be met to satisfy the CPD (known as          the Harmonised Standard);

·        requirements not covered by the CPD (known as the Non-Harmonised or Voluntary Standard).

Technically, a Standard is harmonised once the final mandate for that product group is issued by the Commission and a reference has been published in 'The Official Journal' of the European Community.

Masonry standards are the responsibility of CEN TC 125. The TC125 Standards are generally written in performance terms and have typically followed the principle that they should not exclude products currently in use.  Unlike British Standards, which have always been voluntary, European Standards are effectively mandatory in many circumstances.  The public procurement directives require public bodies and utilities to cite European Standards (both harmonised and voluntary) when they are available.

Mandates

The contract between the EC and CEN is known as a Mandate and commissions the production of Harmonised Standards.  There are three categories of Standards:

  ·        Category A design, installation and execution standards as           exemplified by Eurocode 6.

·      Category B (product) Standards which reflect the characteristics of products described in the Interpretative Documents.

·        Category Bh (horizontal) Standards for methods of test and measurement.

About 600 standards have been mandated under the Construction Products Directive. Work commenced on the development of European product standards (Category B) for masonry with the first meeting of  CEN Technical Committee TC125 in June 1988 but it was not until May 1997 that the Commission issued the mandate for the production of the TC125 standards ( Mandate M116, Brussels, 28 May 1997).

 

 

Levels and Classes
In some Standards it is necessary to require a level of performance which must be met, e.g. in BS EN 771-4 for autoclaved aerated concrete units there is a minimum strength of 1.5 N/mm2 specified.  Classes may also be specified (where a class is a combination of two levels between which the performance must fall), but they cannot be used to prevent the placing of goods on the market if they have been found to be acceptable in any Member State .  The option exists to declare ' no performance measured' for a property if there is no regulation for the property in the Member State concerned.

The CE Mark
Placing the CE mark on a product indicates that the product should be accepted as meeting the requirements of the appropriate Harmonised Standard or has an ETA.  It is therefore able to be placed on the market in any Member State .  Once affixed to a product, testing for non-compliance is the responsibility of the enforcement authorities. In the UK enforcement of the Regulations lies with trading standards officers with the exception of Northern Ireland where it is enforced by environmental health officers.

Attestation of Conformity

The Mandate for masonry products specifies a level of attestation of conformity to support the CE mark, i.e. demonstrates that the products satisfy the requirements of a Harmonised Standard.  All attestation options require the manufacturer to have a factory production control system. Manufacturers of construction products cannot choose which attestation system to apply because these are decided by the EC’s Standing Committee on Construction and agreed by a system of qualified majority voting.

Inspection, testing and certification of products in support of the CE mark must be carried out by Notified Bodies which have been designated for the purpose and notified to the Commission.

Transitional Arrangements

Pending the availability of a harmonised standard or an ETA for a product it can continue to be placed on the market provided it satisfies any existing regulatory requirements in the Member State concerned. Once an EN or ETA is available most states will require the CE mark to indicate compliance.

Eurocodes

The ten Eurocodes deal with the structural design of buildings and civil engineering works and address the first two Essential Requirements. The Eurocodes stem from a decision taken in 1975 by the Commission of the European Community to take action based on article 95 of the Treaty of Rome. Essentially the objective was the elimination of technical obstacles to trade and the harmonisation of technical specifications. In 1989 the preparation and publication of the standards was transferred to CEN where they are the responsibility of CEN TC 250. The potential benefits of adopting the Eurocodes are:

  ·        A common understanding between owners, operators and users, designers, contractors and manufacturers regarding the design of structures.

·        Common design criteria and methods to fulfil the specified requirements

·        Facilitates exchange of construction services

·        Facilitates marketing and use of structural components

·        Facilitates marketing and use of materials and products covered by design calculations.

·        Common basis for research and development

·        Greater transparency for the design process

·        Ability to prepare common design aids and software.

By March 2010 it is intended that all National Structural Design Codes covering the same aspects as the Eurocodes will be withdrawn.

References

1.The Council Directive 89/106/EEC of 21 December 1988 on the approximation of laws, regulations and administrative provisions of the Member States relating to construction products.

2.Amendment of the Construction Products Directive by Council Directive 93/68/EEC of 22 July 1993.