Characterization of Moisture-Induced Swelling in Timber Joining Utilizing Hygroscopic Dimensional Change as an Assembly Mechanism for Wood-to-Wood Connections

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.