Expanding the Functionality of Self-shaping Wood

Integrative Design and Fabrication Methods for Material Programming

Curved geometries have long played a vital role in architecture, offering both structural efficiency and expressive spatial qualities. Traditionally, such geometries are realized through materials like concrete, brick, or steel substructures clad with custom-formed elements such as curved carbon fiber reinforced polymer panels. While these methods enable formal complexity, they come at a high environmental and energetic cost. Timber presents a promising alternative. With a favorable strength-to-weight ratio and the ability to sequester carbon, it offers a more sustainable option for contemporary construction. However, the realization of curved timber surface components remains a challenge. Conventional fabrication techniques—such as mechanical bending, lamination over rigid molds, or subtractive milling—are resource-intensive, leading to high material waste, elevated energy demands, and complex manufacturing processes. As a result, timber architecture continues to rely largely on straight, standardized elements, thereby limiting its potential for structurally efficient and geometrically expressive designs.
In contrast, nature provides alternative strategies for the generation of curvature. Research in plant biomechanics has identified the conifer cone as a compelling example of passive shape change, driven solely by the anisotropic hygromorphic behavior of its lignocellulosic microstructure. Changes in ambient relative humidity cause swelling or shrinkage in the layers of the cone scales, resulting in a autonomous transformation in form. Although such hygromorphic behavior is typically considered a limitation in timber construction, it also offers a potential for material-driven shape change. This principle forms the basis of what has recently been termed self-shaping wood (SSW): a passive actuation technology that leverages the inherent properties of wood to generate programmed curvature without mechanical force. Initial research has demonstrated the feasibility of SSW for creating lightweight, load-bearing structures.
Despite this promise, the full range of architectural applications—and the technical, material, and design challenges associated with real-world implementation—remains largely unexplored.

Aim and Research Questions
This research aims to advance the functionality of self-shaping wood, with the overarching goal of bringing this emerging material technology closer to practical application in architectural, structural, and design contexts. Central to this endeavor is the investigation of programmable material systems at multiple scales, spanning from furniture to building-sized components.
Two primary application scenarios are identified as especially promising for the integration of self-shaping wood. The fabrication, processing and transportation of curved elements is inherently material- and energy-intensive, and incurs significant transport volumes. By exploiting the intrinsic capacity of self-shaping wood to transition from a flat to a curved geometry in response to environmental changes, materially programmed components can be manufactured and transported in a flat configuration and autonomously assume their target geometry on site—with reduced need for onsite labor and scaffolding.
The second scenario addresses the fabrication of large-scale, load-bearing and long spanning curved elements made from cross-laminated timber (CLT). Due to their multi-layered build-up such elements cannot be shaped in a single piece using hygromorphic transformation alone. Instead, self-shaping can be employed as a prefabrication strategy, where individual layers are programmed to curve separately and are consecutively joined together into form stable multi-layered CLT. This approach was first demonstrated in the Urbach Tower, which provides a promising proof of concept. However, many open questions remain concerning the integration of self-shaping strategies into industrial workflows, and the management of geometric tolerances.
From these motivations emerge the following core research questions:
i.    How can material programming be utilized to enable an in situ self-shaping process?
ii.    How can material programming be further developed to support the industrial prefabrication of self-shaped, curved CLT components?

Hypotheses and Methodology
From the two research avenues—(i) in situ self-shaping and (ii) self-shaping prefabrication—result different research hypotheses.
For the first avenue, this thesis builds upon the following hypotheses. (1) Through the development of a computational workflow, material programming can be used for the design and fabrication of in situ self-shaping flat-packed furniture. (2) Through the development of a computational design and fabrication process for material programming of in situ self-constructing architecture, the scaffolding and labor on site can be minimized. (3) Tolerance-aware design and locking strategies can significantly improve the form stability of self-shaped interior objects.
These hypotheses are investigated through case studies in which computational design is employed alongside empirical data acquisition through physical prototyping and full-scale manufacturing. In the first study, a computational workflow for design and prediction supports the fabrication of two SSW furniture prototypes. The second study includes further computational development and material stock management for a robotically prefabricated in situ self-shaping research pavilion. For the third study, long-term curvature measurements in specimens—both in ambient interior conditions and in changing climate in a controlled climate chamber, with and without integrated locking mechanisms—are analyzed.
For the second avenue, this dissertation builds upon the following hypothesis: SSW can be integrated into industrial processes for the fabrication of load-bearing curved CLT components. This is investigated by collecting, analyzing, and evaluating data from the industrial manufacturing of self-shaped CLT and through additional empirical testing. 3D-scanned curvature of the SSW panels is compared to the curvature predictions and material data.

Expected Results and Contribution
This dissertation aims to advance material programming toward its application as a sustainable method for the fabrication and construction of load-bearing curved elements. Built demonstrator projects such as Hygroshape, Hygroshell, and the Wangen Tower showcase the architectural, structural, and functional qualities of self-shaping wood.
Hygroshape introduces a first-of-its-kind concept for in situ self-assembling furniture, enabling flat fabrication and transport. Two full-scale prototypes allow the concept to be experienced in a tangible, haptic way. The research demonstrator pavilion Hygroshell serves as a proof of concept for the in situ self-construction of lightweight, long-spanning building components. This project advances the field by developing a computational workflow that integrates material logistics, fabrication parameters, and design.
The Wangen Tower is the first walkable building to incorporate self-shaped components. The fabrication data generated through this project provides new insights and forms a basis for assessing the feasibility of industrially produced self-shaped CLT.
The design and development of locking strategies address the inherent challenge of long-term form stability in shape-changing materials. In doing so, they support the advancement of SSW for lightweight, sustainable structures with reliable geometry.

ICD Institute for Computational Design and Construction, University of Stuttgart

Laura Kiesewetter, Prof. A. Menges 

DFG Deutsche Forschungsgemeinschaft

Zukunft Bau – Bundesministerium für Wohnen, Stadtentwicklung und Bauwesen / BBSR (10.08.18.7-22.07)

FNR -Förderprogramm Nachwachsende Rohstoffe des BMEL (2221HV096C)

University of Stuttgart – Fund for Knowledge and Technology Transfer

Akbar, Z., Wood, D., Kiesewetter, L., Menges, A., & Wortmann, T. (2022). A Data-Driven Workflow for Modelling Self-Shaping Wood Bilayer, Utilizing Natural Material Variations with Machine Vision and Machine Learning. Proceedings of the 27th Conference on Computer Aided Architectural Design Research in Asia (CAADRIA) [Volume 1], 1, 393–402. https://doi.org/10.52842/conf.caadria.2022.1.393

Alvarez, M., Stieler, D., Kiesewetter, L., Neubauer, G., Göbel, M., Wood, D., Knippers, J., & Menges, A. (2025). INNOVATIVESELF-SHAPING TIMBER CONSTRUCTION: THE WANGEN TOWER. In World Conference on Timber Engineering 2025 (pp. 863–872). World Conference on Timber Engineering 2025. World Conference On Timber Engineering 2025. https://doi.org/10.52202/080513-0108

Cheng, T., Wood, D., Kiesewetter, L., Özdemir, E., Antorveza, K., & Menges, A. (2021). Programming material compliance and actuation: Hybrid additive fabrication of biocomposite structures for large-scale self-shaping. Bioinspiration and Biomimetics, 16(5), 55004. https://doi.org/10.1088/1748-3190/ac10af

Takahashi, K., Kiesewetter, L., Körner, A., Wood, D., Knippers, J., Menges, A. (2025). Structural design and construction of a self-shaping single curved timber structure HygroShell. In Proceedings of the IASS 2024 Symposium

Wood, D., Kiesewetter, L., Körner, A., Takahashi, K., Knippers, J., & Menges, A. (2023). HYGROSHELL-In situ self-shaping of curved timber shells. In Advances in Architectural Geometry 2023 (pp. 43–54). De Gruyter. https://doi.org/10.1515/9783111162683-004