urbach tower is a 14-meter-tall landmark built from self-shaping wood

the university of stuttgart’s institute for computational design and construction (ICD) and institute of building structures and structural design (ITKE) have joined forces to create a 14-meter-tall (46 ft) structure in southern germany. uniquely, ‘urbach tower’ has been constructed using curved wood components that have been ‘self-shaped’. instead of the elaborate and energy-intensive mechanical processes normally used to craft timber, the shape change in the wood used by the ICD/ITKE team is driven only by its characteristic shrinking during a decrease of moisture content.

image © ICD/ITKE university of stuttgart (also main image)

‘in timber construction, moisture typically causes problems with cracking and deformation; hence, moisture changes and stress development must be carefully controlled,’ explains ICD and ITKE. ‘in contrast, in this project wood is programed and arranged in a way to utilize this powerful, naturally occurring deformation to trigger a designed self-shaping behavior. in the same way that machines can be programmed to perform different movements, wood parts can be programmed to transform into predetermined shapes when dried.’

image © ICD/ITKE university of stuttgart

the curved cross laminated timber (CLT) components for the tower’s structure are designed and produced as flat panels that deform autonomously into predicted curved shapes when dried. meanwhile, the 5.m x 1.2m spruce wood bilayers parts are manufactured with a high wood moisture content and specific layups and dried in an industry standard technical drying process. when removed from the drying chamber the parts are precisely curved. the parts are overlapped and laminated together to lock the geometry in place, forming larger curved CLT components with form stable geometry.

image © ICD/ITKE university of stuttgart

‘material specific computational mechanics models have been developed to both design, predict, and optimize the material arrangement required to produce different curvature types and radius,’ continues the design team. ‘the technology of self-shaping manufacturing for solid timber boards and the rapid adaptability of the process to different curvatures open up new and unexpected architectural possibilities for thin shell wood structures, using a sustainable, renewable, and locally sourced building material. the urbach tower is the very first implementation of this technology on building-scale, load-bearing timber parts.’

image © ICD/ITKE university of stuttgart

the tower is one of 16 permanent structures completed for the remstal gartenschau 2019. located on a prominent hillside in the center of the valley, the ‘urbach tower’ visually connects several of these structures, while providing shelter, views, and a venue for internal reflection. externally, the timber structure appears soft and textile-like, with an aperture in the thin wood envelope opening like curtain to present sweeping valley views.

image © ICD/ITKE university of stuttgart

as the building has been designed to be as permanent as possible, a custom-made protective cladding layer consisting of glue laminated larch wood has been added on the outside of each component. this also includes the application of a transparent and durable inorganic coating, which protects the wood from UV radiation and fungi attack. instead of ripping and turning silver-grey when exposed to outdoor weathering, the larch wood will take on an even white color over time. read more about the project here.

image © ICD/ITKE university of stuttgart

image © ICD/ITKE university of stuttgart

image © ICD/ITKE university of stuttgart

image © ICD/ITKE university of stuttgart

image © ICD/ITKE university of stuttgart

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project info:

project team:

ICD – institute for computational design and construction, university of stuttgart

prof. achim menges, dylan wood
architectural design
self-forming curved wooden components research and development

ITKE – institute of building structures and structural design, university of stuttgart

prof. jan knippers, simon bechert, lotte aldinger
structural design and engineering

scientific collaboration:

laboratory of cellulose and wood materials, empa (swiss federal laboratories for materials science and technology), switzerland & wood materials science, ETH zurich (swiss federal institute of technology zurich)
dr. markus rüggeberg, philippe grönquist, prof. ingo burgert
self-forming curved wooden components research and development (PI)

industry collaboration:

blumer-lehmann AG, gossau, switzerland 

katharina lehmann, david riggenbach
self-forming curved wooden components research and development,
wood manufacturing and construction

project support:

gemeinde urbach

remstal gartenschau 2019 GmbH

german federal environmental foundation
design, fabrication and engineering methods for the application of curved wood elements in high-performance, resource-efficient wood construction: project tower urbach, remstal gartenschau 2019

innosuisse – swiss innovation agency
smart, innovative manufacturing of curved wooden components for architecture with complex geometry

carlisle construction materials GmbH
scanntronik mugrauer GmbH

dimensions:

14.20 m tall timber structure
4.0 m radius bottom, 3.0m radius top, 1.6m radius middle
spruce wood CLT with 10-30-10-30-10 build up
larche wood façade with titanium oxide surface treatment
5 axis CNC cut components
12 individual prefabricated components pre-assembled in groups of 3
crossing screw connection detail with wood alignment blocks
8 sensors to monitor internal WMC of the structure

construction system: curved surface active tower structure, self-shaped curved cross laminated spruce timber (CLT) 10 -30-10-30-10 layup, glue laminated larch façade with titanium oxide UV protection surface treatment, curved polycarbonate roof with steel support structure