The joining technique of plugging has a century-old tradition in timber construction and is still widely used today, for example in prefabricated concrete construction. 
Two main approaches to plug connections can be distinguished: highly complex nodes, which are very stiff but difficult to detach, and simpler connections that are easy to assemble and detach. 

There is always a project-related balancing between these two objectives. 

One of the difficulties of plugging as a wood joining technology is the fixation of the components through their geometry. Purely geometric approaches allow for pieces to be joined in a way that they can only be moved in one dimension. With more than two components, the pieces can be joined in a way that they can only be assembled and disassembled in a specific sequence. Another approach is to stabilize the joint through loading it. 

Cross-Section Reduction:
Very complex joint geometries needed for very stiff connections often require a high proportion of the beam cross section to be allocated for stabilization and leave only a small percentage to be used for the transfer of the main loads. Several approaches have been developed here:

- local enlargement of the cross section
- additional connection element
- elongation of the joint
- separating load transfer and fixation of the element

Stiffening of the joint is an important issue due to the limited ability of the connection to transfer momentum. Here, too, there are a number of widely used solutions:
- staggered cantilevers (traditional Japanese)
- plates (balloon frame)
- diagonalized constructions (Central European half-timbered buildings)
- multiple connections acting together (grates)
Back to Top