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.

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.

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.

More than 20% of global carbon emissions are linked with the production of construction materials used in the built environment. The use of bio-materials along with urban densification strategies that avoid demolition and reduce material demand, have been recommended to achieve urban sustainability goals. Addressing these measures, this study compares the life cycle embodied carbon emissions of seven hybrid top-up structural systems composed of concrete, steel and advanced engineered timber products made out of softwood and hardwood species. The life cycle carbon emissions (expressed in kgCO2-eq) were estimated following a cradle-to-grave approach, with a functional unit equivalent to 1 m2 of top-up structural system and focusing on The Netherlands and the city of Amsterdam as main geographical scope. A statistical analysis was included to account for the potential variation of emissions across each life cycle stage, using Monte Carlo simulations for random sampling. The results indicate that predominantly bio-based structures present a staggering 60% lower embodied carbon emissions compared with predominantly concrete, steel and modestly hybrid systems. Preserving the long-term carbon storage capacity of timber elements through high-quality reuse can offset 30–60% of the total positive emissions of the predominantly bio-based systems. Up to 6MtCO2-eq of the national carbon budget in The Netherlands can be saved from a radical uptake of bio-based structures in Amsterdam by 2050. Diversification of material diets with bio-based alternatives is recommended, along with established policy that can guarantee sustainable sourcing and prolonged lifespans through high-end reuse practices.

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.