New Old Architecture

In Europe, you are surrounded everywhere you turn by majestic stone architecture. The Gothic cathedrals and castles that occupy the cities and countryside of Europe provide copious examples of the wonder and beauty of stone architecture.

Stone is one of the oldest materials used in construction. It is also the most durable. The oldest surviving buildings in the world are carved from stone, or made from assembled stones. Göbekli Tepe is made from stone. The Pyramids are made from stone. It’s also a very local material—when you are building from local stone, it gives a place a distinctive feel. That’s why Paris looks the way that it does: the cream-colored Lutetian limestone quarried from the banks of the Seine.

The reason, I think, that we find stone such a compelling material is because, before we built our own structures, we occupied “natural rooms” that the earth made for us—caves. The stone walls of caves, lit by tallow lamps and torches, and illuminated with spectacular artwork, were out earliest permanent homes, and our earliest cathedrals.

The stone walls in a Gothic cathedral or medieval castle are bearing walls, being both the source of shelter from the elements and supporting the overall structure. The walls of modern buildings, by contrast, do not carry any load besides their own weight. The structure is separate, usually a skeleton frame of steel or concrete. These are typically either curtain walls (which are clipped onto or tied back to the supporting structure), or infill walls (sitting on the structure and filling the gaps within it.)

Bearing Walls: Monolithic Masonry Construction (Columbia University)

Walls in commercial construction today are usually cavity walls, consisting of a facing material held to the structure by some sort of clip system, creating a cavity between the supporting structure of the wall (typically studs or masonry) and the veneer. This cavity is designed to resist the penetration of water (since liquid moisture cannot leap a cavity*). The cavity also gives us a place to put the insulation.

Facing materials are usually panelized systems of fiber-cement, metal, porcelain, treated wood, phenolic resin, or some other weather-resistant material. Even in walls that appear to be solid brick or stone, the brick or stone is merely a facing material held by clips to a wall usually comprised of wood or metal studs.

Which is what made this article so fascinating to me: The miracle new sustainable product that’s revolutionising architecture – stone! (The Guardian)

The article talks about having stone be an actual self-supported wall rather than a thin veneer, and also a potential bearing material.

The article is based on a London exhibition of architecture which uses stone as a true building material rather than just a facade veneer. It’s entitled The New Stone Age. Here is the BBC’s coverage:

Design’s new stone age is here (BBC)

Featured prominently is 15 Clerkenwell Close, a six-story building by architect Amin Taha, which uses cut stones as the facing material of the building. The stone is deliberately left in the condition it is quarried in rather than being dressed, leading to variegated facade that resembles an urban ruin. This approach has pleased some, and left others so distressed that they launched a campaign to tear the building down!

…The result looks like what might have happened if Mies van der Rohe had been weaned on The Flintstones. It features a load-bearing exoskeleton made of massive chunks of limestone brought straight from the quarry.

The blocks have been left with their raw quarrying marks exposed and stacked on top of each other to form columns and beams. Some of the slabs’ faces show the lines where they were drilled from the rock face, others are sawn smooth as if cut by a cheese wire, while some bear the rugged texture of the sedimentary seam, freshly pried from the Earth’s crust.

The building’s geological power was too much for one Islington councillor, who complained that the “awful” building was out of keeping with the historic neighbourhood, and ensured that a demolition notice was issued, based on a supposed breach of planning permission. Taha finally won the case last year, on the proviso that the smooth stone be roughened up to look like the rest (a process which, after testing, has thankfully proven structurally too risky to carry out).

The problem with a solid stone wall is that there is no insulation or waterproofing layer as there is in a typical cavity wall. From the details on the architect’s web site, it looks there is a secondary wall behind the stone facade that accomplishes these functions. The stone is stabilized by metal anchors which tie it back to the main structure.

Another building very similar to the one discussed in the Guardian article is 30 Finsbury Square, also in London, by Eric Parry Architects. Unlike Clerkenwell Close, the stone here is dressed and smooth, and facade is designed in a rationalist manner reminiscent of Italian rationalists like Aldo Rossi or Guiseppe Terrangni.

There area few instances where stone is used as both shelter and bearing material. For example the article prominently features a photo of this winery in France:

Delas Frères Winery in France (ArchDaily)

And another example: a radio station in the Himalayas that appears to be built out of solid stonework. It’s difficult to imagine this being built anywhere else, though; I don’t think you could build something like this in downtown London or an American suburb.

The BBC article mentions Jorn Utzon’s (Sydney Opera House) own Can Lis house in Mallorca

The article also prominently features a French firm, Perraudin Architecture, which builds using stone as a structural material, as opposed to just a veneer or facade material. This gives their projects an amazing texture and heft that you just don’t see often in modern architecture. I would imagine France has a tradition of stonemasonry that goes very far back, indeed.

House made of solid stone in Lyon by Perraudin Architecture (Dezeen)

The building is entirely built up in load-bearing limestone walls of 40 cm. Precise coursing elevations define each stone, to be extracted, dimensioned and numbered in the quarry and then transported to the site. There, they are assembled like toy blocks using nothing but a thin bed of lime mortar.

And another example with timeless beauty—social housing in France built out of solid exposed stone walls:

The building is entirely built up in load-bearing limestone walls of 40 cm. Precise coursing elevations define each stone, to be extracted, dimensioned and numbered in the quarry and then transported to the site. There, they are assembled like toy blocks using nothing but a thin bed of lime mortar.

No paint or plaster was added to the walls, so the stone surfaces are left bare to display traces of the quarrying process. Projecting courses of stone on the exterior mark the boundaries between floors and help to direct rainwater away from the windows.

Social housing with solid stone walls by Perraudin Architecture (Dezeen)

But what the article emphasizes is quarried stone as a more environmentally-friendly alternative to concrete. The concrete production process produces and enormous amount of carbon dioxide, whereas stone can by used as quarried directly from the ground. From the Guardian article:

When you step inside the Building Centre, you are immediately confronted with a large model of a speculative proposal for a 30-storey office tower – designed to be made entirely from stone. It looks like a series of Clerkenwell Closes stacked on top of each other, the chunky stone columns getting progressively thinner as they rise towards the clouds.

“We wanted to prove that a solid stone tower is eminently possible,” says Taha, handing me a substantial technical report that makes a hard-nosed case for such a building on grounds of both cost and carbon footprint. Using stone for the core, structure and floors, they argue, would be 75% cheaper than a steel and concrete structure, and have 95% less embodied carbon. The primary reason for the saving is that, while concrete and steel have to be fireproofed, weathered, insulated, then clad, a stone exoskeleton can be left exposed…

“Stone,” says architect Amin Taha, “is the great forgotten material of our time. In 99% of cases, it’s cheaper and greener to use stone in a structural way, as opposed to concrete or steel, but we mostly just think of using it for cladding.”…

The tactile qualities of stone are clear, but, for Taha, the environmental argument is what makes it such an important material to champion. “As a profession, we’re not thinking clearly about the embodied energy of building materials,” he says. “The perverse thing about concrete is that you take limestone, crush it, then burn it, by which time it loses 60% of its structural strength – so you then have to put steel reinforcement inside it. It’s total madness.”

By embracing stone as combined superstructure and external architectural finish, he says, we can save 60-90% of CO2 emissions for these key building elements. “And we’re standing on a gigantic ball of molten rock, so we’re not going to run out of stone any time soon.”

The miracle new sustainable product that’s revolutionising architecture – stone! (The Guardian)

Compare this to concrete:

After water, concrete is the most widely used substance on Earth. If the cement industry were a country, it would be the third largest carbon dioxide emitter in the world with up to 2.8bn tonnes, surpassed only by China and the US….Taking in all stages of production, concrete is said to be responsible for 4-8% of the world’s CO2. Among materials, only coal, oil and gas are a greater source of greenhouse gases. Half of concrete’s CO2 emissions are created during the manufacture of clinker, the most-energy intensive part of the cement-making process.

But other environmental impacts are far less well understood. Concrete is a thirsty behemoth, sucking up almost a 10th of the world’s industrial water use. This often strains supplies for drinking and irrigation, because 75% of this consumption is in drought and water-stressed regions. In cities, concrete also adds to the heat-island effect by absorbing the warmth of the sun and trapping gases from car exhausts and air-conditioner units – though it is, at least, better than darker asphalt.

It also worsens the problem of silicosis and other respiratory diseases…

Concrete: the most destructive material on Earth (The Guardian)

Plus, there’s just something about the “feel” of natural stone that can’t be captured by other materials. That’s why it has faced our buildings since ancient Egypt to ancient Rome and medieval Europe. Due to its “natural” qualities and heft, a solid stone wall simply “feels” better than modern veneer walls, in my opinion. In addition, stone and brick acquire a warm, pleasing patina over time, and are amenable to all sort of creative expression not possible with other panelized systems, and certainly not in aluminum curtain walls. For example, Brick Expressionism (Wikipedia) was common in the early twentieth century, and the beauty, variety, and expressionism of carved stone veneers is evident.

Alongside its sustainable qualities, it’s the material’s one-off nature that really appeals to the design world. “People increasingly want the authentic beauty and inconsistencies of natural stone,” says Solid Nature’s David Mahyari, “imitation ceramic tiles include realistic veins but have a repeat pattern like wallpapers, so you can tell quickly that they’re fake.”

Its age is also a factor. “Stone is a material that is millions of years old. Can you imagine this? I am completely convinced that this dimension also changes the way we relate to a stone object, establishing a different kind of connection with it and making it, somehow, more precious.”

London-based stone carver Simon Smith backs this up: “If the stone ‘takes a polish’, it’s like opening the door of the stone and seeing deep into it, and millions of years back in time.”

I’m not alone. I recently ran across this paragraph describing a project that used stone for vertical shading devices (The Jackman Law Building at the University of Toronto). It explained why the designers fought for natural stone instead of precast concrete for the shading devices:

The choice of stone for the shade fins stems from an aspiration to counter a look of mindless mediocrity that [Architect Siamak] Hariri sees being inflicted on cities by the widespread use of ersatz materials. Imitations lack the dignity, patina, and subtle variety of natural materials, he says, and he advocates for beauty as a value in its own right, as well as for its contribution to durability: “A really good building is one that people will not let be taken down.”

Continuing Education: Vertical Shading Devices (Architectural Record)

Traditionally, stone and brick cannot span spaces except using an arch, a vault (basically an extruded arch), or a dome (a revolved arch). Thus, the structural material in stone buildings was often wood or timber, or steel beams or trusses in newer buildings.

There is a way, however, to have stone span spaces: the flat stone vault, which was patented in the 1600s by French engineer Joseph Abielle. Abeille’s vault has recently been used on an innovative project in Jerusalem: a gift shop added on to an old Crusader church!:

The columns of the new shop are made out of massive stone, and the ceiling is a at stone vault composed of 169 interlocking voussoirs. The system is inspired by the invention of French engineer Joseph Abeille (1673-1756), who patented in 1699 a special system that allowed the building of at vaults.

The Flat Vault / AAU ANASTAS (Arch Daily)

The flat stone vault is completed! (AAU ANASTAS)

Years ago Low-Tech Magazine did a story on the Timbrel and Catalan vaults:

Tiles as a substitute for steel: the art of the timbrel vault (Low Tech Magazine)

The Nubian Vault is constructed of mud brick without requiring a temporary support:

They’ve even used such vaults to construct multi-story buildings without utilizing any concrete or steel:

The Sustainable Urban Dwelling Unit (SUDU) (No Tech Magazine)

These structures can be subsumed under the rubric of reciprocal supporting structures, in which each structural member supports every other member in turn, with a few members transferring the total load to the ground or supports (an interesting metaphor for society, no?). Reciprocal supporting structures are becoming increasingly popular.

Some examples of basic brick monolithic walls are Louis Khan’s Indian Institute of Management, and this house in Vietnam, which uses are perforated brick skin to wrap the house:

Incidentally, I’ve noticed a distinct trend in modern architecture to have not just a single skin, but to divide the exterior and from the interior using layers—for example a layer of sun screening, or a layer for privacy as in the house above, or wrapping balconies around the building to create a “semi-private” space, as in this building:

Colonnades line the terraces of Antonini Darmon’s Arches Boulogne apartments (Dezeen)

I wonder if cementitious foam insulation (Airkrete), sprayed inside a cavity, could give stone the necessary R-values to be used as an exterior wall without a second layer. Waterproofing could be accomplished by a hydrophobic coating. Such a wall would have decent thermal and waterproofing performance, not to mention be practically permanent (and beautiful, too!)

And there are some other promising new materials that can have both a structural use and give a beautiful texture.One that’s getting a lot of attention is cross-laminated timber (CLT). CLT consists of wood planks glued together to create a structurally stable panel (NLT—Nail Laminated Timber, uses nails to hold the planks together). The planks are set together at right angles to each other to provide structural stability, similar to how plywood is made, just at a larger scale. It’s part of growing suite of mass wood technologies:

Mass timber is a generic term that encompasses products of various sizes and functions, like glue-laminated (glulam) beams, laminated veneer lumber (LVL), nail-laminated timber (NLT), and dowel-laminated timber (DLT). But the most common and most familiar form of mass timber, the one that has opened up the most new architectural possibilities, is cross-laminated timber (CLT).

To create CLT, lumber boards that have been trimmed and kiln-dried are glued atop one another in layers, crosswise, with the grain of each layer facing against the grain of the layer adjacent.

Stacking boards together this way can create large slabs, up to a foot thick and as large as 18-feet-long by 98-feet-wide, though the average is something more like 10 by 40. (At this point, the size of slabs is restricted less by manufacturing limitations than by transportation limitations.)

Slabs of wood this large can match or exceed the performance of concrete and steel. CLT can be used to make floors, walls, ceilings — entire buildings.

The hottest new thing in sustainable building is, uh, wood (Vox)

What makes CLT so compelling are two things: the wood facing of the material provides a beautiful surface which can be left exposed on the inside (on the outside you will still require waterproofing, insulation and cladding). But perhaps the most attractive feature is that, since they are made from trees, they remove carbon from the air instead of increase it.

Unlike stone, wood is commonly used to span, and has been the most common material to do so since ancient times. The modern use of CLT leads to a wide range of structural expressions, with nearly endless variation:

Mass Timer Primer
(Canadian Architect)

CLT is the hot material of the moment, and there are many designers who are clamoring to build innovative large-scale structures in this material. There are all sort of proposals out there, from medium-sized buildings to skyscrapers (because we always have to build skyscrapers out of the hot new material for some reason). Although, for smaller-scale and residential structures, I wonder why structural insulated panels (SIPs) are not more popular. Those have been a round for a long time (an innovative use of SIPs is the Ashen Cabin by HANNAH Architecture and Design).

Once upon a time, wood was a primary building material across much of the world. But with industrialization, that changed in the West.

German architect Arnim Seidel explains that steel and concrete became the dominant building materials for to meet 20th-century demands: wide bridges, tall buildings, heavy loads.

“Wood came to be seen as backwards,” Seidel told DW.

Now, its environmental advantages are being recognized.

Materials like steel and concrete require massive amounts of energy to produce, and are usually transported over long distances. This emits CO2 that contributes to climate change.

By some estimates, producing a ton of concrete, or about a cubic meter, generates 410 kilograms of CO2 equivalent — the same amount of energy could power an average house for more than 10 days.

Locally harvested wood from sustainably managed forests not only has a much smaller carbon footprint in its production.

Using wood in buildings also sequesters carbon dioxide. When plants perform photosynthesis, this removes CO2 from the atmosphere and stores it in the wood.

“When we build with wood, we can conserve this stored CO2 for a longer period of time, and not emit it into the atmosphere,” Seidel told DW.

Wood: renewable construction material of the future? (DW)

Another material that is making a comeback is rammed earth:

Rammed earth is the descendant of ancient construction techniques like adobe or cob building. It can be used to build walls for many kinds of buildings, from houses to museums and even cemeteries.

The name says it all: it’s made of damp soil or earth that is placed in formwork, and then compressed or rammed into a solid, dense wall. As a construction technique, rammed earth almost disappeared with the development of reinforced concrete, but there has been a revival in interest because of its aesthetics and its perceived environmental benefits.

The carefully chosen mix of silt, sand, and gravel with a low clay content is moistened and then placed in about 4 inch deep layers between plywood forms; that’s why one sees the different colors and stripes, as often each layer is modified for aesthetic reasons. It used to be rammed by hand, but now powered rams are often used to reduce time and labor. Engineered structural reinforcing is often required.

Electric wiring and switch boxes can be built right into the wall as it goes up, so that a clean, interior earth finish can be maintained.

The structural potential of this material is more limited than the above materials. Cement-stabilized rammed earth has greater structural potential, but usually some sort of additional structure is used. Rammed earth walls tend to be mass walls, and this, along with other characteristics, limits them to fairly mild, drier climates such as the American Southwest, the Mediterranean, and Australia for building.

Like locally-quarried stone, using the earth from the site as a building material also anchors the building to the unique place, and allows us to surround ourselves with materials that look millions of years back in time.

The Dirt on Rammed Earth (Treehugger)

The world’s most beautiful homes are also down to earth (Curbed)

In summary, there are lot of innovative materials, and new ways to use old materials that add up to a lot of design possibilities for building design going forward. Let’s hope we can rise to the challenge and create a more inspiring built environment than has often been the case in the recent past.

* Of course it can, really, such as wind driven rain, but I’m trying to keep this simple!