Spolia; repurposing masonry

It’s safe to say Spolia is having a moment in the spotlight. As ideas of circular economy and materials reuse become established in the lexicon of architectural language, the ancient practice of Spolia is rightly back in the spotlight.

Spolia (from the Latin: 'spoils'; singular: spolium) is the name given to a stone taken from an old structure and repurposed for new construction or decorative purposes. Widely practiced 2000 years ago by the Romans, stone was quarried, cut and used in a built structure to later be dismantled, carried away and used elsewhere. The Arch of Constantine is made-up of stone removed from earlier monuments to Hadrian, Trajan and Marcus Aurelius. Constantine took down the last three emperors’ monuments to build one for himself, replacing their heads with his own.

© Robert Greer

Spolia makes sense. More than half of the total material used to construct a building is attributed to the main structure and envelope. Reusing components from existing, soon-to-be-demolished, or already deconstructed structures significantly reduces the need for manufacturing new components, in turn reducing the carbon cost of the building.

Paye Stonework and Restoration, founding members of The Stone Collective and leading stonework and restoration contractors, have seen a huge growth in interest around the benefits of Spolia. This is in part down to significant reduction In the carbon cost associated with the repurposing of stone façades, alongside the improved thermal performance of the external fabric, and the elimination of inherent steel frame corrosion risk defects.

© Robert Greer

As both experts and custodians, Paye stores entire deconstructed stone facades in facilities in the UK. Arranged library style with a system noting where the stone came from - the course, the horizontal layer of stone and its position on the building’s façade – keeping the stone together where it can be cut negates the need to move stone around the country and further reduces the carbon cost. At the time of writing – September 2024 – Paye has an incredible 4,000 tonnes of dismantled masonry in storage waiting to be rebuilt over the next three years.

Paye are actively embracing new technology to support the process of repurposing masonry, allowing them to provide a greater level of technical certainty. The development in Light Detection and Ranging (LiDAR) and Ground-penetrating radar (GPR) survey accuracy allows for the overall volume of stone within a building to be determined. The existing building acts as a stone quarry, removing the expectation of building with new stone for all repurposing projects.

© Robert Greer

Minimising waste is a key component of sustainable practice. The ‘unpicking’ of structures necessitates a coordinated strategy for deconstruction and needs to be planned jointly by the demolition contractor and the masonry specialist. This care is part of the recognition that materials should be used for as long as they remain functional and reused or repurposed to the greatest extent possible when they reach the end of their service life. Masonry is designed to be durable and long-lasting and can be removed when a building is renovated or demolished, allowing for repurposing.

Spolia has a vital role to play in the importance and value of reclaiming materials to challenge waste and create a robust and climate conscious circular economy. Luckily there is a diminished need for monuments to Emperors but it’s clear that stone and the practice of reusing this sustainable and versatile material is here to stay.

Vanessa Norwood is a curator and consultant for the built environment advocating for low-carbon architecture and materials.