Vienna Architecture Summer School

At the Vienna Architecture Summer School 2025, asphalt led the workshop Oh Oh Oh – Material Strategies on the Otto Wagner Areal in Vienna. Working within a reuse–resource–culture, it looked at architecture and landscape as equal sources of material: archives, fields of potential and places of encounter.

Circular construction usually aims at reuse with as little loss of quality as possible. Brick, steel, aluminium and plastics seem made for this, while renewable materials such as clay, biomass or untreated timber decay and call for a different approach. The workshop treated this apparent contradiction as a design question: what can an architecture look like that combines durable and transient materials, and what new aesthetics come from the interplay of permanence and change? The aesthetic dimension, often neglected in the debate on circular construction, was at the centre.

The starting point was a plant: Japanese knotweed, an invasive neophyte that grows across the site. The group harvested it, then sketched, printed and took it apart. What parts make up the plant? How can it be reassembled? What figures emerge through stacking, layering, bundling and weaving? Tests showed how the material behaves: the hollow stalks are stronger along the grain and far stronger when bundled, the thinner branches stay flexible. In a second step, forms of the historic Art Nouveau buildings were abstracted and tested in mock-ups at 1:20, 1:10 and 1:5, up to a full-scale arch of bundled stalks.

At the end of the week, the workshop's tiled rooms became the exhibition. Sketchbooks, leaf prints, woven samples, models and mock-ups showed the whole process, from the first drawings to the material tests, written directly onto the walls. Knotweed, usually removed and disposed of, became a material to work with, and one that will dry, change and eventually decay.