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 ("MP 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 (non-loadbearing) 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 (aka mass 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: (1) minimizing cuts, which lowers cost and shortens production time, (2) increases the thermal mass of walls for temperature regulation in the building, and (3) 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 (saws) and assembly (cranes) 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 (1959) 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.

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