Affordable Stone: Thoughtful Design of Stone Structures

Concrete and steel remain the dominant materials in construction, in part due to their hidden subsidies from the fossil fuel industry. Meanwhile, natural stone, one of the most durable and beautiful building materials, often appears prohibitively expensive. However, much of this cost is self-imposed through onerous selection criteria, inefficient processing, and outdated construction approaches.

Rethinking Stone Selection

Design teams should begin viewing stone more as a commodity rather than a luxury product. Some quarry owners have been known to hold back perfectly good stone due to its visual characteristics, fearing that selling more varied material could devalue their high-end offerings. By broadening the specification criteria and working closely with suppliers, architects can help drive a shift in mindset that ensures more of the extracted stone is utilised.

From some quarries, as little as 3 to 5 percent of extracted stone is deemed ‘good stone’ (stone that meets stringent specifications for uniformity in colour, texture, and pattern). The rest is often crushed for aggregate, used in landscaping, or simply discarded. Yet, this ‘unloved’ stone is mechanically sound and structurally just as capable as the chosen few. The issue? Modern aesthetics have conditioned us to expect perfection from a material that is naturally diverse.

Historically, stone buildings were designed with this variability in mind. Stone was allowed to weather, developing a natural patina that blended harmoniously over time. By returning to a more accepting approach to stone selection, architects can significantly reduce material costs while embracing the unique character of natural stone.

Learning from Past Builders

Older generations of architects, more intimately connected with stone, were less selective out of necessity. They understood that quarrying stone is a labour-intensive process and made full use of the extracted material, ensuring nothing went to waste. Quarries, in turn, matched the right stone to the right applications: harder beds for lintels, plinths, and cornices, and softer beds for walling and less structurally demanding elements.

Design teams can adopt this mindset by collaborating closely with quarries, specifying stone with a broader acceptance of its natural variations, and designing to make use of standard quarry block sizes rather than imposing arbitrary dimensions that increase processing waste.

Reducing Labour and Processing Costs

Minimising wastage is crucial when working with stone, and this begins with optimising the geometry of each element. Stone is extracted from the quarry bed as rectangular blocks, and any significant removal of material to achieve a final shape increases the likelihood of wastage. If large portions of stone are discarded in the process, more raw material must be purchased to meet the required design. By designing efficiently and considering the natural geometry of quarried stone, architects can reduce waste, lower costs, and make better use of available resources.

One of the largest cost drivers in stone construction is processing. Cutting, finishing, and polishing all add time, energy, and labour to the final product. Using stone in its raw, unprocessed state, straight from the quarry bed, significantly reduces these costs. This approach, long embraced in traditional construction, also adds to the sense of material authenticity.

Traditional stone extraction techniques create unique surface finishes which can be retained in the finished work

Designing for Efficiency

Stone should be used in its most efficient structural configuration to minimise material use. Designing in compression, through the use of domes, vaults, and arches, allows stone to play to its natural strengths, reducing the volume of material required. This not only lowers the base material cost but also significantly reduces the overall weight of the structure, which can lead to further savings in supporting structures and foundations.

Floor shell reduces material volumes by 75% over a conventional concrete flat slab.

Architects can further drive down costs by specifying large-format stone elements. Larger blocks require less mechanical processing and installation time compared to small, highly refined elements. By reducing the level of cutting, shaping, and craneage 'hook time', the cost of stone use drops significantly.

Additionally, stone should be left exposed in its final form. The common practice of overcladding steel and concrete frames with a thin stone veneer is both costly and environmentally inefficient. The steel brackets, shelf angles, vapor barriers, and movement joints required for these systems add complexity, increase embodied carbon, and introduce potential durability issues such as compromised airtightness and weathering. Instead, using stone structurally, as it has been used for centuries, eliminates these unnecessary layers and simplifies construction.

Complex steel bracketry to support a concrete rainscreen to overclad a concrete frame

Embracing Modern Solutions with Traditional Methods

On-site erection and installation time should be minimised to improve efficiency and reduce overall costs. Treating stone as a 'modern method of construction' by utilising prefabricated elements wherever possible can significantly speed up installation. Prefabrication allows for larger, more complex stone elements to be installed in a single operation, reducing the number of trades involved and minimising disruption on-site.

Prefabricated columns being installed by The Stonemasonry Company

To make stone a more viable option in contemporary construction, architects can specify stone products that integrate seamlessly into familiar construction methodologies. Stone bricks, for instance, offer a direct, lower-carbon swap for conventional fired clay bricks. These allow for straightforward adoption by contractors and supply chains without requiring drastic changes to existing construction techniques, equipment or skills,, reducing the risk of additional costs due to unfamiliarity or uncertainty being 'priced-in'.

Polycor stone bricks laid in traditional running bond

Furthermore, an informed Quantity Surveyor who understands the holistic cost implications of stone construction can be an invaluable asset. By considering not just the raw material costs but also the reduction in complexity, labour, and supplementary cladding materials, they can provide a more accurate and fair assessment of stone’s true economic potential. Engaging with a knowledgeable quantity surveyor early in the design process can help architects and clients make informed decisions.

Conclusion

By challenging outdated material selection habits, reducing unnecessary processing, and designing more efficiently, architects can significantly cut the cost of stone structures. This not only makes stone more accessible but also enhances sustainability by reducing waste and embodied carbon. It’s time to rethink our approach to this timeless material, not just as an aesthetic choice, but as a practical, cost-effective, and low-carbon alternative to conventional construction materials.

Thanks to Pierre Bidaud, Marcus Paine, and Will Hawkins for their invaluable insight and advice on this topic