Reuse of traditional joining techniques for single-variety construction

Daniela Schneider

Professorship of Sustainable Construction, Karlsruhe Institute of Technology
Recyclable construction is the basic prerequisite for the urgent demand on how to deal with the worldwide consumption of resources. Buildings must be developed in such a way that the materials can be recycled in a consistent quality. The development of building components includes, among other things, the separation of material layers by type.
Daniela Schneider_375x375

For architects, the design is a relevant planning tool to be able to create a high cycle-compatible quality for building components. In addition to the selection of suitable raw materials and (secondary) materials, the joining technique is decisive for the purely sorted construction. With the help of suitable joining techniques, layers of material can be detached and intended for reuse. The aim is to generate materials as future secondary raw materials already in the design stage in order to make them available to future generations.

Current situation on construction sites

In recent years, the use of highly specialised adhesives and sealants in the construction industry has developed rapidly [1]. For reasons of cost and time savings, adhesives and sealants are preferred for the production of larger surfaces. Due to their elastic structure and action, reworking can be reduced or even prevented. In buildings, adhesives and sealants are used in almost all trades of shell construction, in façade constructions, in building services and in interior finishing. For decades, cement-based adhesives have been used in the facade sector for the installation of external thermal insulation composite systems. Cementitious adhesive components are used for the application of synthetic insulation boards and for the production of a reinforcing layer. During execution, synthetic materials are bonded with a cement-containing adhesive component. Consequently, a separation of the material layers by type is no longer possible.

Preparing the surface of synthetic insulation material for the application of a reinforcing mortar © Daniela Schneider
Preparing the surface of synthetic insulation material for the application of a reinforcing mortar © Daniela Schneider
Planning and execution of detachable fasteners

In the design, the joining techniques suitable for the component are to be planned for their functions appropriate to the cycle. The intended connections are to be defined in the details as well as in the tender in order to prevent the unconscious use of adhesives on construction sites. The implementation of detachable connections on construction sites requires precise specifications on the part of the construction management and reliable processing by the craftsman. This applies, among other things, to the implementation of complex positive and non-positive connections such as screws, clamp connections, snap or zip fasteners. Compared to fabric connections, the implementation of positive and non-positive connections requires more time and the knowledge and experience of craftsmen.

Application of double-sided adhesive tapes for fixing a carpet © Drees & Sommer Switzerland, Anouk Godelet
Application of double-sided adhesive tapes for fixing a carpet © Drees & Sommer Switzerland, Anouk Godelet
Circular design with traditional joining techniques

The focus of cycle-compatible detail planning is directed towards thinking and acting in terms of fasteners. Based on the detailed design, the joining of materials with proven detachable fasteners is crucial. In the design, both the knowledge of detachable fasteners and the exchange with expert craftsmen are required. An approach to design can be provided by the use of traditional joining techniques from the past centuries. These are joining techniques in timber construction that are joined by means of the form or produced by means of the friction-locked connection. Examples include mortise and tenon joints, dovetail joints or the galvanisation of timber components. In traditional buildings, such as the characteristic farmhouse in the Black Forest, hand-beaten shingles and wooden nails made of fir or spruce wood were used to make the roof construction.

Joining roof shingles with wooden nails, Bühlhof in Schönwald in the Black Forest, year of construction 1570 © Daniela Schneider
Conclusion and Outlook
Nowadays, traditionally used joining techniques and fasteners can once again be used for circular planning. Digitalisation facilitates the concrete implementation of traditional joining techniques and their implementation on the construction site. With the help of CNC milling machines, 3D printers and scanners, techniques that have been tried and tested over the long term can be widely applied and further developed for circularity. A creative reinterpretation of traditional joining techniques is fundamentally required as a prerequisite for cycle-compatible planning. The quality of a joining technique that is suitable for recycling allows repair, replacement and reuse of material layers as well as fasteners. Classical traditional joining techniques in combination with digital production should be consciously addressed and taught to younger generations of architects. The aim is to make constructions and materials more durable, more flexible and more durable for subsequent use through the reuse of traditional, separable joining techniques – coupled with the possibility of digitalisation.
[1] Doobe, Marlene: Deutsche Klebstoffindustrie auf Rekordniveau. Hg. v. Springer Professional. (21.09.2021).
Further information about the author

Dipl.-Ing. (FH) Daniela Schneider M. Sc.

Research Assistant and Doctoral Candidate at the Professorship of Sustainable Construction, Faculty of Architecture, KIT Karlsruhe