Tectonical Shape of Wood (2011)

The Erasmus Summer Workshop ‘Wood’ focuses on a number of basic principles of the craft of joinery. Pieces of timber are limited in size. That means that joinery must always be involved when timber components are extended, widened, crossed or turn a corner. The local woodworker shows us the old tradition of joinery not with words, but with his hands.

We will spend two days practising making joints. We will gain an understanding of the properties of timber and the forces that act on joints, and a sense of the material and the required tools. Another workshop exercise concerns the art of engineering and experimentation. Plywood and chipboard possess different properties. The introduction of textile principles, such as weave and grid structures, generates innovative timber objects and structures. Leonardo’s experimental dome of timber slats is a welcome source of inspiration here. Such principles result in open and airy structures in which every piece of timber displays its structural purpose and value. ‘Playing’ with the material confirms and enhances our understanding of the characteristics of the material, such as curvature, distribution of forces and grain.

The second part of the workshop involves making designs for five locations. Concept forms have been devised to enable the material properties previously discovered to draw attention to some aspect of each existing location. A roof above a passageway, the reveal of a church window, an altar in the church, a hammock between trees, and a lampshade in the abbey tower. All designs call for specific solutions to join the different parts. These solutions can be classified according to three interpretations of the concept of joining: connection, composition and coalescence. Each of these concepts denotes another degree of joining.

Connection

Limiting the means of connecting to just timber joints without additional aids (such as screws, rope and glue) leads to creative solutions. What is more, textile techniques also lead to new interpretations of traditional timber joints thanks to the introduction of thrust forces.

That is why half-timber joints have been applied to sheet material in the case of both the ‘altar’ and the ‘hammock’. This allows sheets and strips to connect with one another at an angle. Mortise-and-tenon connections have also been devised to allow strips (hammock) and sheets (lampshade) to be extended. In both cases the mortise-and-tenon connection works like a key in a lock. The connections are therefore reversible. The passageway roof features hinged cross connections made from self-made dowel pins. The woven structures of both the hammock and the reveal include cross connections that make use of nothing but the thrust force of the curved strips.

Composition

The sequence in which the different components are assembled is of the utmost importance when erecting a structure on site. This has a lot to do with the structural and engineering hierarchy of the different pieces with respect to one another. In the shipbuilding industry, for example, the different timber pieces of the ship serve different structural purposes depending on their arrangement. By analogy with the human body, the keel is the spine, the trusses are the ribs, and the planks are the skin. We see a similar hierarchy in a number of the objects made.

The hammock has a number of wide strips that form spines. Narrower strips are woven through these like ribs. Similarly, the passageway roof possesses a number of clear spines whose thrust forces keep them wedged between the two walls. The ribs are then woven through the spines in the other direction.

The curved strips wedge themselves tightly between the two walls that form the passageway, but they are just overlaid to act as hinges. The elegant ‘feet’ against the wall express this connection with moments. The strips perpendicular to these curves ensure that they cannot ‘fall down’. Finally, the altar consists of the same components that serve constantly changing structural purposes. A sheet is alternatively a foundation, a stabiliser, a connector or an ending. Diagonal fastening means that all sheets contribute to the stability and strength of the plateau created. In the altar the hierarchy is hidden in pieces that may look similar but are not all of identical structural value.

Coalescence

The different pieces of timber are connected to one another by new timber joints. Each part of the object has its own function and meaning. The combination of the right joint and the right technical and structural application of the different parts can lead to an ingenious object in which form, function and technique come together. Synergy between appearance, material and structure results when the structure, building technique and formal character reinforce one another. The different parts meld together to form a new configuration in which all elements find their logical place. This results in an object with a self-evident arrangement.

The timber circles of the lampshade are connected to one another using short strips (pin joint). The extended pin strips transfer the forces from one circle to the next. The hierarchy between the circles and the extended ‘pins’ is not as clear as with the column and the rib. The extended pin is not only the key, but also a beam that makes a cantilever possible. The cantilevers are stabilised by the circles that steadily decrease in size and combine with the extended pins to form a rigid structure in which each successive circle ‘presses itself tightly’ against the larger circle outside it. As a result, each additional ring strengthens the whole structure. The largest circle presses the entire structure into place against the wall of the round tower. Each part of the lampshade is essential to push everything into place and keep the air inside. The strips of the reveal extend in two directions. The hierarchy is difficult to read. Arranging the strips in two directions strengthens the whole object. The weave of the reveal is an entity that wedges itself within the window like a stiff textile. The thrust forces are exploited in terms of how the whole structure acts on the window and in terms of the cross connection between the woven slats. This weave is both structure and skin. Structure and appearance meld together to create a sturdy network that can adopt a particular form.

Connection, composition and coalescence are three relevant degrees of joining. Connection caters for the elementary necessity of joining; in composition, the hierarchy of the building process becomes part of the joint; and coalescence proposes a synergy of form, structure and building technique. All three are linked to a greater or lesser degree with the craftsman, the engineer and the designer. The essence of the workshop lies in the search for harmony between the different levels of joining. The woodworker prefers to solve the joint. The engineer looks for the most efficient assemblage. And the designer tries to meld function, technique and structure. The designer’s aim is to learn to switch from craftsmanship to engineering and thus discover new types of joints at all scales in a playful manner by uniting expertise and intuition.

by Machiel Spaan
Academie van Bouwkunst, Amsterdam