A major advantage of using wood as a building material is that the usability of this timber does not necessarily have to end at the end of its useful life. Depending on the condition and quality of the waste wood, it can be reused in many different ways. The waste wood should pass through several stages of utilization. This can be clearly explained using the example of a cascading watercourse. Just as the water slowly flows down the course of the river from stage to stage, losing potential energy with each stage, the waste wood should also be used in one form of utilization after another. Analogous to the energy loss of the water in the cascading watercourse, the wood loses structure with each form of use and can only be transferred to the previous form of use with great effort or not at all. The individual forms of utilization of this so-called cascade utilization are briefly presented below.  

If the waste wood is of good quality, it should first be processed into solid wood. Examples of this are furniture, flooring or wall paneling made from reclaimed wood. Visually appealing effects can be created if, for example, old beams are processed into a new beamed ceiling or tables.

 

If it is not possible to use the wood directly, attempts should be made to produce chip-based products (e.g. pressed chipboard for furniture construction). The wood shavings are first pressed into board form with the addition of an adhesive. The resulting boards are then used as the starting material for new products. In furniture construction, these are usually visually enhanced by covering them with veneers (very thin layers of wood) or decorative foils before processing.

 

After chip-based use, the next smaller wood components, the wood fibers, should be recycled. This can be done in various ways, such as further processing into paper, medium-density fiberboard (MDF) or the viscose fibers presented in Chapter 5.

The final material use of waste wood is the production of chemical products. The substances lignin, cellulose and hemicellulose (the main components of wood) can be the starting materials for a variety of products. Processing can take place in a biorefinery plant; one such biorefinery plant is operated by the Fraunhofer Center for Chemical-Biotechnological Processes (CBP) in Leuna, for example. A short presentation of this plant can be seen in the following video

 

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