Twenty tonnes sat on a wooden plate held up by columns alone, 200 people watched, and the plate moved 12 mm. That was in June 2026 at the Future Cleantech Festival in Remscheid. The University of Stuttgart announced the result on 23 September. The ICD project page calls the demonstrator “the world’s first successful construction of a point-supported, multi-axial long-span flat slab in timber–concrete composite construction.”

Glulam and concrete are old companions; what changed is the computation. A patent-pending segmentation method cuts any floor outline, regular or irregular, into prefabricated glued-laminated-timber segments with straight laminations, and sets each segment’s fibre direction to follow the force flow. The grain is laid the way an engineer lays rebar: wood has always carried load best along its fibres, and now the fibres are told where the load is going.

The team is led by Prof. Achim Menges (ICD) and Prof. Jan Knippers (ITKE). It includes Hans Jakob Wagner, who heads the EU project, along with Martin Alvarez, Juan David Frank Spinel, Tim Stark, Gregor Neubauer and Renan Prandini, plus IABP, IWB and MPA at Stuttgart and BUILT CoLAB in Porto. According to the university’s release, AI-assisted tools generate models for many floor-plan variations and report cost, slab height and sustainability in real time. CORDIS lists the funding: European Innovation Council Pathfinder grant no. 101161103, EUR 3.26 million, running to September 2027. Industry did the making. HASSLACHER Group fabricated the segments and Dünschede Holzbau assembled them in two days, three months from planning to completion. The laminators and carpenters who turned a computed pattern into a floor deserve the credit too.

A plate on columns

The test piece measures 9 x 5 m and spans 8 x 4 m in two directions. It is 36 cm deep, about what an equivalent reinforced-concrete slab needs, and uses roughly two-thirds less reinforced concrete. It was designed for 1.4 kN/m² of finishes and 3.0 kN/m² of live load, which is a busy office. Under the 20-tonne test it deflected at most 12 mm and kept a natural frequency above 8 Hz, and the measurements confirmed the simulations. Knippers put the moment plainly: “The first load test wasn’t conducted in the lab, but in front of the approximately 200 visitors at the Future Cleantech Festival in Remscheid.”

Until now, timber floors have meant one-way spans, beams and load-bearing walls. The flat slab on columns is the reason concrete still owns the office floor. Compared with conventional timber systems, the release claims 30–70 cm less structural height per storey and up to 20 % less facade area, with no load-bearing partitions. Menges states the aim: “to make multi-story timber-concrete composite construction significantly more flexible, performative, and adaptable.” Wagner adds: “The system builds on the existing manufacturing expertise of the wood construction industry.”

Building-sense: A building with this floor would feel its loads travel along grain chosen for them rather than across it. It would stand on columns and keep its rooms free to change. Such a body can be re-partitioned for a century without surgery.

←TODAY: In a test in Germany, a 36 cm timber-concrete flat slab carried 20 t on columns alone. →3012: Every floor’s grain is computed from its loads before a tree is felled. Fulcrum: The material was ready decades ago; what arrived now is the geometry that tells it where to point.

The trade-off is plain. This is a research demonstrator. No fire, acoustic or Swiss approval data has been published, so an SIA-based project cannot specify it yet. From the far side of the century I ask one more thing: when this body dies, can its timber and concrete layers be separated and reused? The release says reinforced-concrete slabs account for about 40 % of buildings’ embodied carbon. Ask how the composite comes apart before you count what it saves. The first pilot, the Zukunftsforum in Oberkochen (three storeys, 1,400 m²), will say more than any render.

Atelier: For a Zürich or Bern office doing a feasibility study on a commercial block under a height limit, storey height is the lever. A columns-only timber floor at concrete depth is now a credible option to sketch, though not yet to tender. The Monday move: add a 36 cm point-supported slab variant to the massing and compare it with your timber-beam baseline before you brief the engineer.

Hack: Count how many storeys a thinner floor buys under a fixed height limit. The inputs below are only examples, so swap in your zone’s limit and your own floor-to-floor height.

H, base = 25.0, 3.9   # height limit, timber-beam floor-to-floor (m)
for saved in (0.3, 0.5, 0.7):
    print(saved, int(H // base), int(H // (base - saved)))
# 0.3 -> 6 vs 6 · 0.5 -> 6 vs 7 · 0.7 -> 6 vs 7

Put the same lines in a GhPython component fed by your massing’s real levels.

Model the 36 cm variant, count the storeys it gives you, and take that number to your engineer.