Timber plate shells as a roof construction system : design and fabrication of trivalent polyhedral roof structures for applications in the existing building stock

Abstract

This dissertation investigates the applicability of timber plate shells as a construction system for roof structures of buildings, departing from an architectural perspective and focusing on vertical densification projects. Timber plate shells are a lightweight timber construction system that can expand the architectural vocabulary and can contribute to sustainable construction, but only few timber plate shells been constructed so far. This dissertation aims to identify and resolve potential impediments to the design and construction of timber plate shells, and to collect information and insights that may contribute to a broader application of timber plate shells in the construction sector. Various plate and joint types are discussed and two plate types with distinct joint types are investigated further: solid cross-laminated timber plates connected with crossing screws and hollow laminated veneer lumber components connected with finger joints and bolts. These plate types are assessed on criteria such as structural properties, weight, fabrication methods, material efficiency, environmental impact, air and moisture tightness, sound, thermal insulation, integration of air ducts, and costs. Furthermore, spatial typologies, strategies that deal with various architectural design considerations and approaches for the design of plate shells and the connection between global design and segmentation patterns are investigated, and contributions to geometric design methods are introduced. While the practical application of plate shells depends on the willingness of timber contractors to build in a currently unconventional way and on the willingness and ability of architects to use design methods that are novel and challenging, timber plate shells have all the qualities necessary to play a significant role in the construction sector as a lightweight, sustainable and economical roof construction system that is particularly suitable for vertical densification projects.