Eurocodes in the supply chain
Dr Keerthi Ranasinghe, Senior Structural Engineer at TRADA Technology Ltd, in High Wycombe, UK, urges timber and wood products suppliers to consider CE marking or third-party certification to take advantage of Eurocode 5’s effect on designing with timber.
A key aim of the Eurocodes has been to create a common understanding about the design of structures among construction professionals. This in turn will lead to a common design criterion and further methods for meeting regulatory requirements. The Eurocodes are also part of the drive to eliminate technical obstacles to trade between EU member states, opening up opportunities for timber suppliers prepared to do their homework.
Although Eurocode 5 (EC5) is very much a design code, suppliers should be aware that timber designers working to it need a product’s characteristic values for their calculations.
Manufacturers and suppliers, therefore, need to understand what characteristic values are relevant for their products and use approved or codified methods of testing to obtain them. A product certification scheme helps manufacturers and suppliers to obtain these values, as required by EC5.
The timber standard consists of three parts – common rules and rules for buildings, structural fire design, and bridges. Each part has its own national annex (NA). All three parts have already been published, along with all the NAs, most of the supporting standards and most of the harmonised product standards. There is little reason, therefore, for either designers or product suppliers to hold back from embracing EC5 wholeheartedly, apart from unfamiliarity.
Fit for purpose
The European Construction Products Directive (CPD) classifies a ‘construction product’ as a product ‘which is to be incorporated in a permanent manner in construction works’. The CPD requires EU member states to ‘take all necessary measures’ to ensure that such products are sold ‘only if the product is fit for its intended purpose’. The CPD is incorporated in UK law by the Construction Products Regulations 1991 (Amended 1994), which adopts the Essential Requirements (ER) from the CPD.
Construction products, when they become part of a building, must conform to the Essential Requirements on –
- Mechanical resistance and stability.
- Safety in the case of fire.
- Hygiene, health and environment.
- Safety in use.
- Protection against noise.
- Energy economy and heat retention.
All products will be required to demonstrate that they have the necessary characteristics to achieve at least one, many or all of these ERs, depending on their end use, and this is the responsibility of the manufacturer/supplier.
Although CE marking is not a legal obligation for construction products in the UK, demonstrating compliance with the CPD is and can most easily be done through CE marking for markets throughout Europe. An alternative is third-party certification under a national quality assurance scheme, which requires a higher level of proof of conformity than CE marking.
CE marking is likely to be incorporated into the regulations by 2013. Manufacturers who want to steal a march on the competition are looking into the system ahead of time. The award of a CE mark requires a specific level of input by a notified body that may operate within and outside Europe to assess products for use in Europe. In the UK, notified bodies for construction products include BM TRADA Certification, Building Research Establishment and the British Board of Agreement. Notified bodies are not enforcement agencies, and it remains the manufacturer’s responsibility to affix the CE mark to the product correctly. By the same token, it is the buyer’s responsibility to check that CE marked products are what they say.
A whole range of construction products and materials are already covered by harmonised product standards or through European Product Approval Guidelines (ETAGs), enabling them to be marked easily. These include structural timber and related products (glued laminated timber, laminated veneer lumber, I-joists and other engineered wood products), wood-based panel products (plywood, OSB, particleboards, fibreboards), fasteners and connectors, trussed rafters and timber frame building ‘kits’.
Compliant and certified
Notified bodies can also help certify new products that are not yet covered by a standard or ETAG – a further opportunity for manufacturers to identify niche markets.
Previously, under British Standards, new materials could only be permitted in design when the standard was revised, so it could take years to have them included. Eurocode 5, however, separates the design method from the material properties, so these can be investigated and certified independently of the structural design codes. It is considered only a matter of time before everyone involved in the timber industry wakes up to this potential – to make efficient use of existing timber materials and to come up with innovative designs which embrace new materials.
The market is slowly waking up to all that EC5 can offer. Our advice to manufacturers and suppliers, therefore, would be to forget the grey areas of overlap between BS 5268 and EC5. The question is no longer when should we start learning about the requirements of Eurocode 5, but who will get there first?
Dr Keerthi Ranasinghe, Senior Structural Engineer, TRADA Technology Ltd, Stocking Lane, Hughenden Valley, High Wycombe, HP14 4ND. t +44 (0)1494 569600 e email@example.com