Less Concrete, More Innovation in Staircase Design

Researchers from FMAA at USI and GKR at ETH Zurich have developed a method to make concrete staircases lighter, more adaptable, and significantly less carbon-intensive. The result, the "Vertebra" staircase, uses about half as much concrete and produces 32% fewer CO₂-equivalent emissions than conventional precast stairs.

Real-size demonstrator of optimised staircase design. Image by © Fabrication & Material Aware Architecture (FMAA) 2024

Staircases are essential architectural elements, connecting floors and shaping spaces, yet most are plain, heavy, and standardised — the familiar type found in schools, offices, and apartment buildings. The Fabrication and Material Aware Architecture (FMAA) group at Accademia di Architettura USI, supported by the NCCR DFAB and building on foundational research at Gramazio Kohler Research (GKR), ETH Zurich, explored whether staircases could be made more material-efficient and flexible without increasing cost or construction complexity.

Their approach combines three innovations: recyclable paper formwork, augmented-reality-guided steel placement, and concrete made with recycled aggregates. Foldable, recyclable paper formwork replaces bulky wooden moulds, enabling customised geometries while reducing weight and waste. Augmented reality guides the precise placement of steel reinforcement inside the stair elements — like a digital overlay showing exactly where each bar should go. The concrete itself is produced using recycled aggregates, further lowering carbon emissions.

After casting, the paper-based formwork is being removed. Image by Fabio Amicarelli

Together, these methods resulted in the Vertebra staircase, a full-scale demonstration of how design and technology can work hand in hand. The steps are lighter and structurally efficient while also visually distinctive, showing how even a familiar building element can be reimagined. By rethinking a basic component such as the staircase, the project highlights how construction can become both more innovative and more resource-conscious.

The researchers behind this work also founded Foldcast, a company developing paper-based formwork for a wider range of construction applications. Applying the same principles of recyclable, lightweight, and adaptable moulds beyond staircases, Foldcast aims to make flexible formwork a practical alternative to standardised systems across the building industry.

This article is based on the paper titled, “Advancing Precision. Less concrete, more innovation in staircase design” and was published in ARCHITECTURAL INFORMATICS, Proceedings of the 30th International Conference of the Association for Computer-Aided Architectural Design Research in Asia (CAADRIA) 2025. Authors are Fabio Amicarelli, Elia Quadranti, Christian Paglia, Eleni Vasiliki Alexi, Inés Ariza, Megi Sinani, Fabio Gramazio, Matthias Kohler and Ena Lloret-Fritschi.