Hempcrete Arch

An experiment in how natural materials behave structurally. Formed from hempcrete blocks, plywood ‘chocks’, and hemp rope, the piece explores form, adaptability and reuse through simple construction.

The shallow catenary curve form relies entirely on compression. The ropes close the system at the base, holding everything in place without glue, screws or any permanent fixings. It can be taken apart, moved and rebuilt easily.

The blocks, supplied by The Hemp Block Company, are typically employed for non-load-bearing applications. Set out in a geometry that works with the inherent properties of the material, we’ve demonstrated that form and tolerance can unlock structural strength in unexpected places.

The arch was modelled parametrically, allowing the optimal length and height to be explored and tolerances tested before anything was built. Increasing the area of the plywood would let it take more load, and casting the hemp instead of using blocks could strengthen it further.

Lightweight compared to stone or concrete, the structure intended to show what can happen when natural materials are given structural intent.

During the exhibition launch, however, the arch collapsed after being pushed a little too far by our Director. Rebuilding it exposed how sensitive the geometry was to small changes. Minor chips from the fall, slight variations in block size, and a bit of stretch in the rope created tiny hinges that disrupted the compression path.

The failure became part of the experiment, showing how even low-strength materials can behave unpredictably once their tolerances shift. Next time, we’ll tighten the geometry and materials so the structure is more resilient and easier to rebuild.