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Eurocode 5: Code for Structural Timber Buildings

The European Standard EN 1995, or "Eurocode 5: Design of timber structures" is a standardised European design standard that establishes common rules across the European Union for structural design of timber buildings. It is one of a suite of new Eurocodes for structural design, based on European Standards including steel, concrete and masonry amongst others. Eurocode 5 is intended to replace the national design standard BS5268 and remove potential barriers to trade that exist when countries have different design standards. It will also in part feed into the UK Building Regulations Approved Documents, particularly Approved Document A (Structure).

Eurocode 5 is made up of 3 Parts (see Table 1 below) that are being adopted in all EU Member States in 2010. Each Part is implemented nationally with a National Annex. These Annexes contain country-specific design data that allow Eurocode 5 to be adapted to local conditions such as differing snow depths, wind speeds and other design parameters. BSI ratified the UK’s National Annex to Eurocode 5 in 2006, bringing the Eurocode officially into use as a parallel alternative to BS 5268.

Under an agreement between the European standardisation bodies, BSI the national standards body for the UK will withdraw all parts of BS 5268 by 31 March 2010. BS 5268 will remain available from BSI but BSI committees have already stopped updating this British Standard, and so it may not necessarily be suitable for aspects of structural design in the medium and long term.

Table1: list of the BS EN 1995 structural design standard parts, and the corresponding British Standards which will be withdrawn by BSI by 31 March 2010

Eurocode 5: Design of timber structures Corresponding BS

BS EN 1995-1-1:2004 Design of timber structures. General. Common rules and rules for buildings

BS 5268-2, BS 5268-3, BS 5268-6.1*,
BS 5268-6.2*, BS 5268-7.1*, BS 5268-7.2*
BS 5268-7.3*, BS 5268-7.4*, BS 5268-7.5*
BS 5268-7.6*, BS 5268-7.7*

BS EN 1995-1-2:2004 Design of timber structures.
General. Structural fire design
BS 5268-4.1*, BS 5268-4.2*
BS EN 1995-2:2004 Design of timber structures. Bridges _

Note:
* These standards are not directly, or are not currently referenced in the UK Building Regulations Approved Document A (Structure).

The fundamental difference between BS 5268 and BS EN 1995 in design terms is that Eurocode 5 is a theoretical design code rather than a code of best practice, so formulae replace tabulated values. Eurocode 5 contains only the essential rules and formulae for design and because it is formula-driven it lacks the quick look-up tables of BS 5268. However the National Annex which contains the country-specific material properties also includes some tables of loads and other design data which were written into BS 5268.

From a commercial point of view, major changes in timber usage and specification are unlikely. However:

  • Characteristic strength properties for panel products and components such as timber I-joists and metal hardware must now be obtained in accordance with CEN testing standards;
  • Floors may have to be a little stiffer (i.e. more timber);
  • Large roof structures without brittle finishes may not require so much timber;
  • There will have to be yet more reliance on software for the design of trussed rafters, connections and timber frame walls.

Please click on the links below to download further information on the change to Eurocode 5.

BSI Introduction to Eurocode 5

Trada Wood Info - Eurocode 5 Introduction

Eurocode 5 (EC5): Design of Timber Structures. An Overview & Comparison with the BS 5268-2 Method