The European basis for the structural design of timber structures is Eurocode 5 (EN 1995). Its second generation has now been published – and for the first time it includes CLT, cross-laminated timber. In short: the design of CLT buildings is moving onto common, uniform European rules. Here is a summary of what is changing, when, and what you gain from it as a client.

The timeline

  • 1 August 2025 – the new EN 1995-1-1 (general rules) and EN 1995-1-2 (structural fire design) were published; countries can begin implementing them.
  • 30 September 2027 – the deadline for every national standards body to publish its national version.
  • 30 March 2028 – the first-generation Eurocodes are withdrawn.

The transition therefore takes place over the next two years: for buildings designed in 2027–2028, the new standard will apply.

What is new?

CLT and LVL are now in the standard. Until now, CLT design usually relied on manufacturers’ technical assessments and on the literature. The new standard gives rules for every main timber product and groups products that behave similarly – making design simpler and more uniform.

Vibration. The guidance on checking floor vibration has been improved. For lightweight floors – and a CLT floor is one – vibration often determines the thickness.

Openings in beams. New rules cover holes in beams, that is, where and how large an opening can be made for building services.

Reinforcement and connections. Comprehensive guidance on reinforcing timber members has been added, the design of connections has been reorganised, and carpentry joints and glued-in rods are now included.

Durability. More detailed guidance on how to achieve the intended service life.

Fire. The new fire design part (EN 1995-1-2) extends the calculation method to CLT, and extends the verification of separating elements and connections up to 120 minutes of fire resistance.

Execution. A new part (EN 1995-3) sets minimum requirements for production, assembly and erection. Its aim is simple: what has been designed should be built that way.

Why is this good for you?

  • A common, recognised basis. The structural design of a CLT structure rests on a uniform European standard. This makes it easier to choose between manufacturers: the design is not tied to the data of a single product.
  • Easier checking. With common rules, an independent checking engineer or the authority can review the calculation on a clearer basis.
  • Comfortable floors. The improved vibration check helps ensure that the floor is comfortable in everyday use.
  • More flexible building services. The rules on openings in beams make it easier to route services.
  • Fire safety in numbers. The fire resistance of CLT can be verified with a standard method, for up to 120 minutes.
  • The design is built as planned. The execution part makes it clearer what the factory and the installers must comply with.

What to watch out for during the transition

  • Scheduling. If the design falls in 2027–2028, it is worth clarifying in advance which generation of the standard the structural design will follow.
  • National annex. Every country sets some national parameters – for example safety factors and snow and wind loads. The details of the national version in your country also need to be followed.
  • Earthquakes. Seismic design is not part of Eurocode 5 but of Eurocode 8 – the two must be applied together.

How we help

We specialise in the structural design of CLT structures: we work to Eurocode 5 with finite element models and calculate deflection, floor vibration, fire resistance and seismic behaviour. During the transition, we clarify when scheduling the project which generation of the standard the calculation will follow.