| Standard | Title | Reference Tools | Reference Table |
|---|---|---|---|
| EN 1995-1-1 | General - common rules and rules for buildings | - | - |
| EN 1995-1-2 | General - structural fire design | - | - |
| EN 1995-2 | Bridges | - | - |
What this standard covers
EN 1995 (Eurocode 5 - Design of timber structures) is the European standard for structural timber, glued-laminated timber and wood-based products, together with their connections.
EN 1995-1-1 gives the general rules for buildings: strength classes, the modification factors that account for moisture and load duration, member design in bending, tension, compression and shear, and the design of joints made with nails, screws, bolts, dowels and connectors. EN 1995-1-2 covers fire and EN 1995-2 bridges.
Two features distinguish timber design. Strength depends on the duration of the load and on the moisture content of the timber, both handled through the modification factor kmod applied to every strength property. And timber is strongly anisotropic - it is much weaker perpendicular to the grain than parallel to it - so the direction of stress relative to the grain matters in a way it does not for steel or concrete.
What you will find in it
- Strength classes
- The C and D classes for sawn timber and the GL classes for glulam, each carrying a full set of characteristic strength and stiffness properties.
- Service classes
- Classification by the moisture conditions the timber will experience in service, which affects both strength and deformation.
- Load-duration classes
- Permanent, long-term, medium-term, short-term and instantaneous actions, since timber carries a short-duration load better than a permanent one.
- Modification factors
- kmod for service class and load duration, and the further factors for size, system effect and instability that adjust the basic resistance.
- Member design
- Bending, tension, compression and shear parallel and perpendicular to grain, and the combined checks including lateral-torsional stability.
- Connections
- Nailed, screwed, bolted, dowelled and connectored joints, designed on the European yield model with the rope effect where applicable.
- Serviceability
- Instantaneous and final deformation including creep, and vibration of timber floors, which frequently governs a domestic floor joist.
When to use this standard
Use EN 1995 for timber, glulam and engineered wood members and their connections under the Eurocodes. Strength classes come from EN 338 for sawn timber and EN 14080 for glulam. In North American practice the equivalent document is the NDS, which uses a different adjustment-factor system and is not interchangeable with this one.
How it fits with the other standards
Actions come from EN 1991, combined under the rules of EN 1990. Material properties are classified by EN 338 and EN 14080, and seismic design adds EN 1998.
What each part covers
- EN 1995-1-1
- The general part for buildings: strength classes, the kmod modification factors for moisture and load duration, member design in bending, tension, compression and shear, and the design of connections.
- EN 1995-1-2
- Structural fire design. The charring of timber with time and the residual section that carries load, which is how timber fire resistance is assessed.
- EN 1995-2
- Timber bridges. Applies the general rules to bridges, with the durability and fatigue requirements that outdoor exposure and traffic impose.