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Timber construction is currently the strongest growing sector in the construction industry. In 2020 it grew by 13.6%. But what does this mean for building practice?

Status quo

In Europe, the construction industry is responsible for about 40 percent of material and energy consumption. Concrete alone causes 8 percent of CO2 emissions worldwide. As a result, more and more showcase projects are emerging that aim to significantly reduce the amount of concrete used in buildings. Multi-storey residential and office buildings made of wood are thus attracting more and more attention.

Advantages of timber construction:

The advantages of timber architecture are quickly listed:

  1. wood is climate-friendly
  2. wood is light
  3. wood can be used flexibly
  4. wood has a balancing effect on room humidity
  5. wood has a balancing effect on temperature fluctuations
  6. wood is suitable for adding storeys due to its low weight and thus enables effective redensification and conversion
  7. wood (building materials) can be easily reused after deconstruction. (= From an ecological point of view, an immense advantage over conventional reinforced concrete buildings).
  8. timber (construction) can significantly shorten construction times due to the high degree of prefabrication of building elements and the largely dry construction method
  9. timber (construction) leads to significantly fewer defects and lower liability risks than conventional construction methods

As a result, timber construction leads to more sustainability and thus, with the increasingly important ESG criteria, also to a better rating in bank financing.

Disadvantages of the timber hybrid construction method:

Unfortunately, the disadvantages of timber construction are listed just as quickly:

  1. there is still a lack of knowledge about the raw material in building practice, especially among planners, but also among builders and authorities.
  2. As a result, approval procedures are delayed because the state building codes do not yet reflect the current state of the art.
  3. As a result, the planning effort for architects increases due to the lack of approval specifications.
  4. In addition, the high degree of prefabrication requires detailed planning much earlier than with conventional solid construction. This means that planning must already take into account production, transport and assembly in the design process. 5.
  5. Timber (constructions) generally have a high stability and load-bearing capacity in case of fire. However, fire safety regulations are currently (still) very high and complex for taller buildings, which is why timber hybrid buildings are (still) required.
  6. Another problem is the higher complexity due to hybrid construction!  This is because fire protection, sound insulation, moisture protection and heat insulation always have to be provided jointly by shell and finishing elements. In many cases, component approvals are not yet available and approvals are (still) difficult to obtain in individual cases (see points 1 – 3).
  7. Internal sound insulation is an additional problem! Here it is important to know the possibilities and limits of the achievable sound insulation of (current) solutions.

As a result, the requirements in the early service phases of the planning increase and with them the fee costs for the planning.

Conclusions:

Basically, a new project organisation and a new basic understanding of building with wood is required.

As described above, the usual separation of planning and execution in conventional construction leads to the important criteria in the timber construction process being integrated too late in the planning process.

Rescheduling in the building process becomes necessary. The effort, the project duration and, as a result, the costs increase.

Two approaches to a solution:

Approach 1:

German architecture and engineering offices build up their own know-how, similar to the level of architecture and engineering offices in Switzerland.

However, this is (currently) still unrealistic in Germany, also because the profession of timber construction engineer does not exist here.

Approach 2:

The (currently) more pragmatic option is an adapted project organisation.

In contrast to the planning offices, sufficient competence already exists in Germany in the field of timber construction. The contracting of timber construction should therefore take place in the early planning stage. As a result, the executing firms can contribute their expertise in good time. Later rescheduling can thus be reduced.

Another advantage of early involvement is the development of optimal solutions in the award competition and thus a reduction in costs.

In addition, it is recommended to involve an external consultant with timber construction expertise as a second opinion.

 

A (holistic) task remains

What happens if the German construction industry actually recognises the advantages of building with wood and at the same time comes to grips with the disadvantages?

Will sustainable forestry be able to meet the growing demand for wood at all?

In the long term, the only solution is a circular construction industry. The new timber building structures must serve as a material reserve and must already be designed in this form today. The basic properties of timber building materials already leave every possibility for this today.

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