Xylotek's team has been involved in the design and making of gridshell structures over the last two decades. Through our projects, and in our support of academic research, we have been developing variants of the technique seeking new geometric possibilities and structural refinement.
Gridshells are lattice structures of long thin timber laths, generally laid up in two directions and formed into a doubly-curved shell structure which has been geometrically form-found to act efficiently as a compression-only (dome-like) shape. They exhibit a highly materially efficient structural arrangement for enclosing space with a lightweight lattice structure, typically used for medium and long-span roofs.
The most common approach to forming gridshells is to lay out an initially flat grid of laths, then push up the interior of the grid into the intended arching shape, imparting the double curvature that makes the shell stiff and locking that in with diagonal bracing cables. The result is an exceptionally light-weight, beautiful, and materially efficient structure.
The gridshell is an example of a 'bending-active' structure in which there is a highly interdependent relationship between the geometric form and the structural behaviour. Effective gridshell geometries need to be computationally form-found using dynamic relaxation techniques that simulate the physical behaviour, in a process analogous to an inverted hanging-chain model.
We have particular experience in glazed gridshells and the issues involved in managing the tolerances and interfaces between the elastically-formed timber and precise stiff glazing panels.
We are currently building a gridshell using pre-formed glue-laminated doubly-curved laths that each follow 'geodesic' curves across the roof's virtual surface. This means that each lamella can be a straight flat plank which develops into the lath shape through twisting and one-direction bending only. It allows a refined single-layer gridshell of curvatures only possible through lamination.