This research investigates the structural behavior of timber joints under moisture-induced dimensional change and explores the potential of hygroscopic swelling as a mechanism for wood-to-wood joinery. The study is framed as a proof-of-concept for climate-activated timber connections that could support prefabricated construction systems in humid environments such as rural Colombia. The methodology combines material experiments, digital fabrication tests, structural analysis, and mechanical testing. First, the dimensional response of selected timber species was measured under controlled humidity conditions. Second, the manufacturability and assembly behavior of traditional joinery types were evaluated using CNC fabrication. Finally, mechanical tests were conducted on mortise–tenon joints and cross half-lap joints to assess the influence of different humidity conditions on the structural performance on these connections. Across the investigated configurations, specimens conditioned at higher relative humidity consistently reached higher peak loads than corresponding control samples. These observations indicate that moisture-induced swelling can increase contact pressure and friction within timber joints, thereby influencing load transfer behavior. The study provides initial findings that hygroscopic dimensional change can be used as an active parameter in timber joinery and may support the development of climate-responsive, prefabricated construction systems. ... Read more

This volume presents “Timber for Urban Density,” a TU Delft compendium of graduation projects and research (2018–2025) that position wood as structural method, urban resource, and cultural project. It advances a pedagogy where drawing, prototyping, and full-scale coordination are inseparable, and where reversibility, traceability, and life-cycle literacy shape detail and assembly. The book is organized around built proposals and essays that translate circular ethics into construction logic and city-scale policy. Design theses test timber across climates and programs: intergenerational housing frameworks and adaptable domestic typologies; neighbourhood top-ups that treat the city as forest through modular rooftop extensions; tropical dwellings negotiating humidity, rainfall, and craft; and resilient community infrastructures whose components are graded for reuse. Collectively they foreground demountable joints, stock-aware dimensioning, and serviceable layers that keep structure legible and teachable. Research chapters consolidate the operating system for practice. A “transparent guide” for Dutch timber construction couples maximum carbon storage with minimum embodied energy; a parametric high-rise study shows how layout and material choice drive footprint; bamboo and wood-technology papers extend the palette with moisture-induced joinery and multi-storey tropical systems; additional essays integrate forest ecologies into urban planning and probe acoustic performance in timber interiors. Together they outline standards, testing pathways, and stock-discretion methods that convert irregular urban feedstock into calculable, re-deployable elements. The result is a clear call to action: design to the available stock, standardize where it counts, keep connections reversible, and align architectural expression with ecological accountability. ... Read more

Anatomy of Timber celebrates wood as the future of architecture, tracing how designers, engineers, and makers are reinventing building culture through craft, ecology, and innovation. Born from an international forum, the book brings together bold ideas and real projects that show timber’s power to connect forest to city, structure to climate, and design to responsibility. It’s a call to build beautifully, intelligently, and sustainably, with timber at the heart of it all. ... Read more

Timber has regained popularity in construction in recent years due to its ecological benefits. The connection methods used in this study play a vital role in the sustainability of structures and materials. Monomaterial timber connections are sustainable alternatives to metal fasteners and adhesives commonly used in construction. Wood is an anisotropic material with dimensional changes resulting from changes in atmospheric conditions. Understanding and accounting for this property are crucial for the longevity and functionality of wooden structures. The cumulative knowledge of wood´s material characteristics and its use in design, construction, and human culture can be defined as wood culture developed through artists’ and craftsmen’s experiences, science, and industry. The development of various techniques by artisans to leverage the dimensional change in wood to join timber elements is a major contribution to wood culture. In contrast, until now, the timber industry has mainly focused on limiting or controlling these changes in standardized production and has neglected their use for joining timber elements. However, technological advances have changed dramatically. The digital manufacturing and analysis of wood structures have the potential to guide machine tools and may allow the integration of dimensional changes, especially in the design and construction of timber joints. This study explores the state-of-the-art utilization of dimensional changes in timber to join elements in craft, material science, and industrial production. The potential of techniques utilizing this behavior for innovation in modern design and construction and their implications for wood culture were examined. Research gaps and avenues for further research are identified. ... Read more

From a global perspective, the building industry stands as a significant factor of environmental impact on the planet. Wood has emerged as a promising construction material as a sustainable building source, gaining traction in the industry due to its carbon storage capabilities and prefabricated possibilities [13]. Particularly in the context of rural Colombia, the integration of prefabricated timber constructions, coupled with advancements in digital fabrication technologies, holds the promise of facilitating social reconstruction. Furthermore, such an approach poses the potential to enhance material performance and contribute positively to its end of life [1].

Nevertheless, existing research identifies a critical gap within the wood-to-wood timber connections to tackle better design, manufacture, assembly, and deconstruction (DfMA + D) [20]. Consequently, this study endeavours to explore the application of Computer Numerical Control (CNC) technologies in conjunction with the material's response to changes in relative humidity. The aim is to devise a mechanism for tight-fitting structural wood connections, the central focus of this research lies in understanding the collaborative interaction between sawn timber and moisture fluctuations. By doing so, the study seeks to introduce a new construction methodology and building system centred around material climate reaction and its expansion capacity applications in traditional connections, thereby mitigating the need for chemical and mechanical structural joints, ultimately resulting in a self-assembly system destined to low-income populations in the Colombian territory. This study proves the enhancement of timber connection to tensile stress up to 50% of its original capacity by implementing the moisture induced process and developing a building system utilising this joining method for the assembly of elements for housing in Colombia. ... Read more

The rapid advancements in technology call for a new approach to disseminating knowledge, emphasizing inclusivity, open accessibility, and collaborative intelligence. This shift towards an inclusive, open-source community facilitates global online connections that enhance the exchange of techniques and knowledge, further enabled by digital planning tools integrating design and execution seamlessly. Such advancements have revived interest in timber joints, combining traditional craftsmanship with digital design and manufacturing innovations. The Timber Joinery Database was established to preserve and expand this heritage by creating an open-source online platform for documenting both traditional and innovative timber joints. The development of the database included the structuring, design and technical conception as well as the integration of the first entries for evaluation. This work allows for the continuous implementation of joint analyses, developments and physical models production, bridging traditional craftsmanship with modern manufacturing methods. As the database evolves, it is enriched with more parameters and a parametric framework to cater to user-specific customization needs, ensuring the project's relevance and application in current and future timber joinery practices. This initiative represents a blend of tradition and innovation, leveraging digital tools and open-source principles to advance the field of timber joinery. ... Read more

The :metabolon project demonstrates resource-saving, renewable and circular building materials, space-saving design, and construction methods through two experimental housing prototypes. Designed as research demonstrators, the model houses exemplify individual work and living spaces with minimal space requirements and efficient, multifunctional use of spaces. The houses, based on the modular timber construction system INTERACT developed by the CODE-ARCH research unit at the Cologne University of Applied Sciences, feature efficient use of space and rely on a digital production chain. The project aims to showcase innovative and sustainable architecture and promote a holistic life cycle approach, including monitoring energy consumption, material use, user behavior, and well-being. The paper discusses the architectural concept and process steps, including the integration of technical aspects and the further development of the INTERACT system. ... Read more

The InterACT research project focuses on the use of computational design and manufacturing methods in the construction of self-build projects based on wooden structures. The goal is the interdisciplinary development and realization of a prototypical laboratory on the university campus in Cologne. At the intersection of craftsmanship and architecture, the project aims to generate, collect and share interdisciplinary knowledge. The InterACT Lab is intended to function as a hybrid learning and research space, uniting theory and practice. Moreover, the project should make the concept of networked learning and research visible beyond the academic boundaries. The entire development of the project has been set-up as a participative and collaborative learning process, involving students in the conceptual design, decision making and the production of the building components as well as in the assembly of the structure, using digital tools as a common base and connector throughout the process. The paper presents the didactic concept and discusses the findings of the various steps from the early design phase to the realization of a first prototype in scale 1:1. ... Read more

Worldwide there is a big need for affordable livingspace. Globalization leads to a connection of development and ideas in the field of building. Open Source communities could improve and accelerate this development. The potential of theses communities lies in the connection of different diciplines. Especially for building projects with a small budget and a willingness to participate in the work process open source do-it-yourself constructions are a great opportunity to help cover the need of affordable work and living space. Renewable materials such as wood offer great potential here. New, standardised technologies make a decentralised production possible.

... Read more