Massive precut stone


Massive-precut stone is a modern stonemasonry method of building with load-bearing stone. Precut stone is a DFMA construction method that uses large machine-cut dimension stone blocks with precisely defined dimensions to rapidly assemble buildings in which stone is used as a major or the sole load-bearing material.
A key technique of massive-precut stone is to specify precut stone to precise dimensions that match the architect's plan for rapid construction, typically using a crane. The blocks may be numbered so that the masons can follow the plan procedurally. The use of massive stone blocks has several benefits, listed below.
Massive-precut stone construction was originally developed by Fernand Pouillon in postwar period who referred to the method as "pierre de taille" or "pré-taille" stone. It became possible through innovations by Pouillon and Paul Marcerou, a masonry engineer at a quarry in Fontvieille, to adapt high-precision saws from the timber industry to quarrying and stone sawing.
Massive-precut stone is also known as "prefabricated stone", "pre-sized stone", "megalithic" construction, "massive stone", or simply "mass stone". However, these terms have various namespace conflicts with other stonemasonry techniques like synthetic stone, cosmetic precut stone, or older methods of massive handworked stonemasonry. MP stone has a close affiliation with tensioned stone as compatible methods of modern load-bearing stonemasonry. Similarly, massive-precut stone has a connection to mass timber as allied low-carbon construction methods using traditional structural materials in a new context.
Since 1948, MP stone buildings have been constructed in France, Algeria, Iran, Switzerland, Palestine, the United Kingdom, Spain, and India. The re-adoption of MP stone inspired architecture critic Rowan Moore to speculate that "It's conceivable, indeed, that the era of concrete will prove only an interlude in the far longer history of stone."

Design features

MP stone is defined by five design attributes. These differentiate MP stone from both traditional stonemasonry and modern non-load-bearing or non-DFMA stone methods.
  • Load bearing. This distinguishes MP stone from cosmetic precut stone, which is used for cladding decoration.
  • Massive blocks. Using massive dimensions has three critical benefits: minimizing cuts, which lowers cost and shortens production time, increases the thermal mass of walls for temperature regulation in the building, and makes use of crane construction, thereby lowering manual labor, shortening assembly time, reducing mortar, labor, and cost.
  • Precise offsite dimension cuts. Precutting can be done at the quarry, or at a masonry workshop by sawyer and banker masons. The precision amounts to a form of prefabrication, such that the masons do not have to make adjustments onsite, and construction is an assembly process. Precise interfaces also reduce the amount of mortar required.
  • Machine fabrication and assembly. Unlike traditional stonemasonry, cutting and assembly is primarily done with machines.
  • Design for manufacturing and assembly. The architect will design the building to specify each ashlar's dimensions. Blocks are to be designed to be as modular as possible, ideally with a handful of different shapes. Reducing the types of shape simplifies manufacture. Pouillon was able to build large housing projects faster and cheaper than the competition, in part due to his DFMA process.
    "Exactly how Pouillon brought the 2,635 apartments of the 1959 Résidence du Parc in Meudon-la-Forêt online in record time and at less-than-market prices remains a mystery no-one seems to want to see solved." – Graham McKay.

    Types of construction

There are three implementations of massive-precut stone.
  • Massive-precut monolithic ashlars. Blocks cut precisely on four to six sides, used to assemble walls, lintels over windows and doors, and in flat arches. The first major use of this variation was in the La Tourette and Vieux-Port redevelopment projects.
  • End-shaped massive-precut monoliths. Quarry-finished dimension stone blocks with precisely shaped ends for assembly into post-and-lintel frameworks. The first implementation of this method was in the 15 Clerkenwell Close building, completed 2017.
  • Massive-precut cyclopean concrete blocks. Developed by IBAVI in Mallorca, rough stones are placed in a mold and saturated with concrete. The concrete is sawn into massive ashlars for crane assembly. Enables reuse of rough plum stones from traditional stone masonry. The first documented architectural use of precut cyclopean concrete blocks was in a social housing project on Mallorca in the early 2020s.
  • Tensioned stone. Stone beams and columns can be strengthened by drilling a duct that is threaded with a tension cable. After assembly with grout, the cables are tensioned using standard pre-stressing jacks. Both pre- and post tensioned stone can be used.
MP stone is typically used in conjunction with other materials, notably for floors, as unreinforced stone is unsuitable for tensile spans. It has most often been used together with reinforced concrete floors, but plans are in place to use it with cross-laminated timber floors, and post-tensioned stone floors. Reinforcing massive precut stone with post-tensioning reinforcement would make it strong enough to substitute for reinforced concrete in a wide range of applications.
In 2024, UK industry group the Stone Collective was formed to promote construction with stone, and advance education in this area.

Benefits

MP stone construction has five key advantages over non-massive stone and brick masonry, concrete, wood, and other conventional construction methods.

Specific benefits

  • Build speed. The use of precisely cut and numbered ashlars, combined with crane-assisted assembly, significantly reduces construction time compared to traditional stone masonry techniques. Compared to concrete construction, MP stone is faster as there is only a limited setting wait time.
  • Simplicity. Amin Taha compares a stone-clad concrete column with a stone column. The former demands multiple layers: steel, concrete, fireproofing, waterproofing, stone cladding, and the fixtures connecting them; all require the various specialized workers for installation. The latter is a block of stone that is installed by masons using a crane and mortar.
  • Design efficiency. Simplicity improves design efficiency, enabling architects to generate and iterate building designs quickly. Use of DFMA and modularity improves the chance of project success.
  • Labor efficiency. The use of cranes and a well-organized construction plan reduces the labor required, lowering costs and reducing the wait time for skilled mason availability.
  • Cost reduction. Compared to brick masonry or smaller ashlars, using larger stone blocks, means that the overall expense of constructing a building can be reduced.

    General advantages

  • Environmental benefits. The use of a material with lower embedded carbon contributes to a more sustainable building process, minimizing the environmental impact. Lower carbon emissions: load-bearing stone construction emits around 1/10th the carbon as a comparable concrete building. As 80% of energy is non-grid fossil fuel, and construction is respoinsible for 8% of carbon emissions, the replacement of coal-burning concrete production with lower-energy dimension-stone production could have a substantial impact on net-zero goals.
    "Imagine: we currently crush, burn and chemically mix limestone to make cement for concrete that then has 40 per cent of the strength of its original strength, needing steel to reinforce it. Why do we use concrete then?"
  • Durability. Buildings constructed using massive precut stone maintain the inherent durability and longevity of stone construction, offering long-lasting and low-maintenance structures. Historically, load-bearing stone is the most durable construction method. An engineering analysis of a 20-storey unreinforced MP-stone tower has suggested this method has good seismic resilience:
    "With regard to the current Algerian seismic design regulation, the results obtained in terms of time period, frequency, storey drifts and displacements showed that the ... '' ... tower can be considered as an earthquake-resistant building fulfilling the required structural safety conditions."''
  • Aesthetics. Compared to concrete and other materials, massive precut stone construction yields visually striking and distinctive buildings that showcase the natural beauty of stone. There is a trend away from artificial stone products due to their fake image. "People increasingly want the authentic beauty and inconsistencies of natural stone; imitation ceramic tiles include realistic veins but have a repeat pattern like wallpapers, so you can tell quickly that they're fake."
  • Reusability. When a building has reached the end of its usefulness, rectilinear ashlars are easily reused as spolia in new construction.
  • Thermal performance. As with traditional stone construction, massive precut stone buildings benefit from excellent thermal mass, helping regulate indoor temperatures and reduce energy consumption for heating and cooling.
  • Fire resistance. Compared to wood and other products, stone has far superior fire resistance, so requires little or no additional fireproofing.

    Controversies

MP stone has been ignored or resisted by mainstream architects, engineers, and developers, for reasons including the following.
  • Belief that dimension stone is too expensive for non-luxury load-bearing construction. Depending on the context, this may be true if quarries are not developed for large precision blocks. However, in the early 2020s, quarries in France and Italy were able to furnish cost-effective precision-cut stone. Amin Taha of Groupwork points out that using stone directly obviates the use of fireproofing, waterproofing, stone cladding, associated fixtures, and cuts labor costs, while simplifying design and design iterations.
  • Claim that MP stone cannot be safely used for tall structures. This view is contradicted by two 70-yo towers standing >50 m, located at 2 Rue Saint Laurent, Marseille; and Diar Es Saada, Algiers, the latter of which is close to a fault. Also the stone towers of cathedrals that have lasted for centuries, and ancient tall stone structures—like the 48-m Pont du Gard—that have stood for millennia.
  • Unsuitability of MP stone for long spans, including floors. Due to its poor tensile strength, stone cannot be used for long spans, so, architects and builders must switch modes during design and construction of horizontal and vertical components. MP stone can be used in conjunction with concrete floors, manufactured timber panels, and post-tensioned stone flooring units.
  • The mainstream modernists, who were focused on concrete, steel, and other new materials, disliked the continuity with the old world that MP stone represented. This disregard for stone in fact violated Louis Sullivan's maxim that "form follows function".
  • Following the construction of 15 Clerkenwell Close, the quarry finishes on the blocks was opposed by a local councilmember due to claims about heritage style and aesthetics. Ironically the use of load-bearing rusticated stone is an ancient style and the use of limestone was specifically appropriate to the site, which was the site of a limestone Norman abbey.
  • In many nations, quarries produce aggregate, or dimension stone is only produced for cosmetic veneers, not structural purposes. This means that the most abundant natural construction resource is inaccessible to most of the world's population. This explains why the method has been used most extensively in France, where the quarrymasters and other stonemasons are knowledgeable in load-bearing stone. The presence of heritage stonemasons in many regions suggests that there is the potential to restore structural stonemasonry in many countries.
  • There is the perception that stone quarries are destructive to the environment. This position ignores the fact that concrete and steel each require multiple quarries and mines, along with intensive carbon release due to extraction and heating.