What do you do when the material you're told is modern and efficient starts crumbling at fifty years, while buildings made of the supposedly obsolete stuff have been standing for five hundred? Hannah sent us a prompt this week, and she's been thinking about stone. Not as a pretty facade stuck onto a concrete frame, but as the thing holding the building up. She writes...
I want to talk about stone as a structural material, not as an aesthetic choice or cladding. Structural stone construction largely stopped about a hundred years ago, except in some village traditions. The more I learn about reinforced concrete, the more I see its serious flaws — environmental impact, non-recyclability, and short lifespan. How can a building be called sustainable if it crumbles after fifty years? Yet when you suggest building structurally with stone, people look at you like you're crazy.
But most historic cities were built with stone, and many remain in excellent condition after hundreds or even thousands of years. She mentions a video by The Aesthetic City that advocates for traditional architecture — she's not dogmatic about making buildings look old, but she believes in examining pre-modern methods that worked well. Stone can be almost carbon-neutral, is cut at the quarry and assembled like Lego blocks, requires less skilled labor, has excellent thermal mass, lasts forever, and can be reused. It creates buildings people love and want to care for, which is the most important aspect of sustainability.
There's a growing movement in Europe to revive structural stone. She wants to know who's doing this and what they're building — traditional methods for six to eight story buildings, not stone skyscrapers. Second, how do we solve the technical challenges: insulation, earthquake resistance, lack of tensile strength. Third, the economics — could it be affordable at scale since stone is already excavated for concrete, and local quarries reduce transport. And finally, locally in Jerusalem — is anyone exploring this here? How would you convince developers, contractors, engineers, and regulators? Where would you even begin?
She's asking the right question at exactly the right moment. There are engineers cutting stone right now for load-bearing buildings in London and Zurich, and most of the construction industry hasn't noticed yet.
So let's unpack what structural stone actually means, and why it's not just about aesthetics.
Structural stone means the stone is carrying the load — the weight of the floors, the roof, the people inside — not just hanging off a steel or concrete frame as decoration. Most of what we call stone buildings today are concrete buildings wearing a stone skin. Structural stone is the opposite: the walls themselves are the structure. And the distinction matters because it changes everything about how the building performs over time.
The thing people miss is that concrete has a built-in expiration date. The steel rebar inside it rusts, expands, and cracks the concrete from within. Fifty years is optimistic in a coastal climate.
And the carbon cost is staggering. Cement production alone accounts for about eight percent of global CO2 emissions. That's more than aviation and shipping combined. Every ton of cement releases roughly a ton of CO2 — the chemical reaction itself produces it, not just the energy to heat the kiln. You can't efficiency your way out of chemistry.
So we're building the world's cities out of a material that emits a ton of CO2 per ton produced, can't be recycled, and starts failing before the mortgage is paid off. And we call this progress.
Meanwhile the stone buildings of Jerusalem's Old City have been standing for five hundred years, and they'll be standing five hundred years from now if we don't knock them down. The stone itself doesn't degrade. Mortar joints might need repointing every century or so. That's the maintenance schedule.
Which brings us to who's actually doing this. You mentioned London and Zurich.
Webb Yates Engineers in London. They're one of the leading structural engineering firms doing this work, and they've got two projects completing this year. One is a stone footbridge — a pedestrian bridge made of load-bearing stone blocks, post-tensioned with steel tendons running through them. The other is a stone-framed office building, where the primary structure is stone rather than steel or concrete. Building Design magazine profiled them earlier this year — they're calling it the start of a new stone age, which is maybe a bit much, but the work is real.
A stone footbridge. The thing people think stone can't do — span an opening — and they built one.
Post-tensioning is the key. You drill channels through the stone blocks and thread high-strength steel tendons through them, then tension the steel. It compresses the stone, and stone is phenomenally strong in compression. The steel handles the tension forces, the stone handles the compression, and suddenly you've got a material system that can span distances and resist bending moments that unreinforced stone never could.
So it's not traditional dry-stack masonry. It's a hybrid.
It's a hybrid, but the stone is doing most of the work. In a concrete building, the concrete is just a matrix to hold the steel — the steel carries the tension, the concrete protects the steel and carries compression. Post-tensioned stone flips the ratio: the stone is the primary structural element, and the steel tendons are a small fraction of the total material volume.
What else is being built?
Architectural Record ran a piece earlier this year called Structural Stone Makes a Comeback. They profiled a post-tensioned stone vaulted hall in France — a large public space with a sweeping stone ceiling, entirely load-bearing. And a residential building in Switzerland, multiple stories, where the exterior and interior walls are structural stone. Not cladding, not veneer. The walls hold up the floors.
Switzerland. That's earthquake territory.
Moderate seismicity, yes. And that's one of the technical challenges Hannah raised. Stone's the classic brittle material — strong until it isn't, then catastrophic failure with no warning. Concrete has the same problem, which is why we reinforce it. But engineers are solving this with ductile joints — connections between stone elements that can deform and absorb energy during an earthquake without the whole structure collapsing.
How does that actually work?
Think of it like... a stone column that's not one continuous piece. It's segments with steel connectors between them, and those connectors are designed to yield — to stretch and deform — during a seismic event. The stone segments themselves stay intact, but the joints absorb the energy. There was a test building in Japan — full-scale, on a shake table — that demonstrated this. Stone structure with ductile connections, subjected to earthquake-level ground motion, and it performed.
Japan's a good place to test that. If it works there, it works anywhere.
The Japanese researchers used a post-tensioned stone system with energy-dissipating devices at the joints. After the simulated earthquake, the stone elements were undamaged. The only components that needed replacement were the sacrificial energy dissipators. That's a fundamentally different philosophy from conventional seismic design, where you expect the structure itself to be damaged and potentially need demolition after a major quake.
So the building survives and you swap out the fuses. That's better than the concrete approach, where the building survives but it's condemned.
Exactly the right analogy — they're structural fuses. And this connects to another innovation Hannah would want to know about: CNC-cut interlocking stone blocks. Computer-controlled cutting at the quarry produces blocks that fit together with millimeter precision, no mortar required. They're like giant three-dimensional puzzle pieces. The Metropolis magazine analysis from this year pointed out that this eliminates the most skill-intensive part of traditional masonry — the mortar work and the precise positioning — and makes on-site assembly dramatically faster.
So the "requires highly skilled masons" objection is backwards. Modern structural stone uses less skilled labor on site than concrete formwork.
The skill moves to the quarry, where the CNC machines do the precision cutting. On site, you're essentially stacking numbered blocks according to a plan. It's more like assembling prefabricated components than traditional stonemasonry.
Which is how we build with steel and precast concrete already. Nobody hand-forges steel beams on site.
Right. And this is where the economics get interesting — actually, let me pause on the technical side for a second. There's one more thing. Metropolis magazine's lifecycle analysis found that structural stone can reduce embodied carbon by up to eighty percent compared to reinforced concrete. Eighty percent. That's not incremental improvement, that's a different category of material.
Eighty percent less carbon and it lasts ten times longer. The math seems straightforward.
The math is straightforward. The industry isn't. So let's talk about why.
So the technology works. But does it make economic sense? That's where it gets interesting.
The number people throw around is that structural stone currently runs ten to twenty percent more expensive than reinforced concrete, upfront. But there are several things wrong with that comparison.
Start with the thing people forget.
The lifespan. A concrete building has a design life of fifty to a hundred years, and that's with maintenance — and by maintenance I mean eventually you're patching spalled concrete and dealing with corroded rebar, which is expensive and disruptive. A structural stone building has a design life measured in centuries. The stone itself doesn't have a failure mechanism. If you amortize the construction cost over five hundred years instead of fifty, stone is cheaper by an order of magnitude.
But developers don't think in centuries. They think in exit strategies.
That's the real obstacle, and we should be honest about it. A developer who plans to sell the building in five years doesn't care about year fifty, let alone year five hundred. The economic case for stone depends on either a long-term owner — a university, a government, a family institution — or on regulation that prices carbon and durability into the equation.
Or on convincing people that a stone building will command higher rents and resale value because it'll still be beautiful in thirty years when the concrete building next door looks like it's melting.
That's the intangible. Hard to put in a spreadsheet, but real. People pay more to live in stone buildings. They just do.
What about the raw material cost? You mentioned stone is already being quarried.
This is the part that makes the whole thing almost absurd. We already quarry enormous quantities of stone — for concrete aggregate. We blast it out of the ground, crush it into gravel, and mix it with cement to make concrete. Using that same stone structurally doesn't require new quarries or new extraction. It requires different cutting and finishing at the existing quarry.
So we're taking a material we're already extracting, crushing it into bits, and gluing it back together with a high-carbon binder, instead of just cutting it into blocks and stacking it.
When you put it that way, it sounds insane.
It is insane.
The crushing and reconstituting adds cost and carbon. A stone block cut to shape at the quarry has a single processing step. Concrete requires crushing, heating limestone to fourteen hundred degrees to make cement, mixing, pouring into forms, curing. The supply chain is vastly more complex.
And the transport argument? Concrete ingredients and steel rebar get shipped all over the place.
Local stone quarries exist near most cities — Jerusalem certainly has them. The stone for Jerusalem's buildings has historically come from quarries within a few dozen kilometers. Transporting finished stone blocks is heavy, but so is transporting concrete and steel. The Metropolis analysis pointed out that when you use local stone, the transport emissions are comparable or lower than concrete, especially since you're not shipping cement from a centralized plant.
What about insulation? Stone walls are thick and heavy, which helps with thermal mass, but modern energy codes want R-values that a solid stone wall can't hit on its own.
Two approaches. One is external insulation — you put a layer of rigid insulation on the outside of the structural stone wall, then protect it with a rainscreen or render. The stone provides the structure and the thermal mass inside the insulation, which is actually the ideal configuration for most climates — the mass is inside the thermal envelope where it can absorb and release heat slowly.
And in Jerusalem's climate, that thermal mass is genuinely useful. Hot days, cool nights — the stone soaks up heat during the day and releases it at night.
Jerusalem is practically the poster child for thermal mass. The traditional stone buildings here stay cool in summer without air conditioning, because the thick stone walls absorb heat slowly and radiate it back out at night when temperatures drop. Modern concrete buildings with lightweight block infill don't do that — they heat up fast and you need mechanical cooling.
So the insulation problem is solved. External insulation on a stone structural wall gives you the thermal performance and the mass benefit in one package.
The Swiss residential project I mentioned used a double-wall system — two layers of stone with insulation between them. That works too, though it uses more stone. Either approach meets modern energy codes. The physics isn't the problem.
The problem is codes written for concrete.
Building codes in most countries don't have a chapter for structural stone. They have chapters for reinforced concrete, structural steel, timber, and masonry — but masonry means unreinforced brick or block, with strict height limits and no post-tensioning provisions. If you want to build a six-story post-tensioned stone building, you're using what's called an alternative means and methods clause. You have to prove to the building official that your design meets or exceeds the performance requirements of the prescriptive code.
Which means hiring an engineer who's willing to do the paperwork and take the liability.
And that's expensive and slow the first time. The second time, you've got a precedent. The tenth time, it's routine. But somebody has to go first.
Now let's bring this home to Jerusalem, where stone is already everywhere — just not load-bearing.
Jerusalem's building code already mandates stone cladding on many facades. The city decided decades ago that buildings should look like Jerusalem, and the way you do that is stone on the outside. So every developer here is already buying stone, already hiring contractors who work with stone, already dealing with stone's weight and detailing. But it's all veneer — thin stone panels hung off a concrete structure.
So the stone is already in the budget. It's just doing nothing structurally.
It's dead weight hanging off the building. The concrete frame carries the stone cladding, instead of the stone carrying itself and the floors. It's the worst of both worlds — you pay for the concrete structure and you pay for the stone, and the concrete is doing all the work while the stone is cosmetic.
If you made the stone structural, you'd eliminate the concrete frame and the cladding attachment system. The stone would do both jobs.
That's the argument. And in Jerusalem, where stone is culturally and regulatorily familiar, the conversation doesn't start from zero. The contractors know stone. The regulators know stone. The clients expect stone. The leap is getting them to see it as structure rather than skin.
So where would you begin? Hannah's question is practical — if she wanted to convince a client and contractor to build this way, what's step one?
Step one is not a manifesto. It's a pilot project. A small building — maybe a two or three story residential structure, or a municipal building where the city is the client and has a long-term interest in durability. Something small enough that the alternative methods engineering isn't a multi-year ordeal, but real enough to generate cost data and performance data.
A municipal building is smart. The city owns it forever, so the lifespan argument actually lands. And if the municipality does it, the regulatory path gets smoother for everyone else.
Step two is finding a structural engineer who's willing to do the alternative methods submission. That's the bottleneck. You need someone who understands post-tensioned stone or is willing to learn, and who has the credibility with the building department to get a novel system approved.
Are there engineers in Israel doing this?
Not that I've found in the published literature. But Israeli engineers are trained in the same structural principles, and post-tensioning is a standard technique in concrete construction here. The concepts transfer. It's a matter of someone deciding to apply them to stone.
So you'd need to import expertise for the first project, or send a local engineer to study the Webb Yates projects in London.
That's realistic. Fly someone to London, walk them through the stone footbridge and the office building, let them talk to the engineers who designed the post-tensioning system. The knowledge exists — it just hasn't been brought here yet.
Step three is the contractor. You said CNC-cut blocks eliminate the need for skilled masons. But someone has to assemble them.
A crew that can do precast concrete erection can do CNC-cut stone assembly. The skills are similar — reading shop drawings, operating lifting equipment, positioning large elements. Jerusalem's construction industry has plenty of contractors who do precast work. The tooling is different but the workflow is familiar.
And the quarry. You need a local quarry willing to invest in CNC cutting equipment.
That's a chicken-and-egg problem. The quarry won't invest without demand, and there's no demand without supply. This is where a committed client — say, the municipality — can break the logjam by guaranteeing a certain volume of cut stone for a pilot project. Once the equipment exists, the marginal cost of cutting additional blocks drops.
What about convincing developers? The private sector is where this would need to scale.
Developers need three things: a cost number they can put in a pro forma, a construction schedule they can finance, and a product they can sell or rent. For the pilot project, you're not going to beat concrete on upfront cost — accept that. You're selling something else: a building with lower lifetime costs, higher tenant satisfaction, and a marketing story that no other building in the city can tell.
The first structural stone residential building in Jerusalem in a century. That's a headline.
It's a premium product. And Jerusalem's real estate market already supports premium pricing for stone-clad buildings — people pay more for the look of stone. A building that is stone, structurally, with the thermal performance and durability that implies? That's a different tier entirely.
Green building credits could help close the gap. If the embodied carbon is eighty percent lower, that's points under any green building standard.
And Jerusalem's planning authority already incentivizes certain sustainable features — green roofs, for example. Extending that to structural stone through density bonuses or expedited permitting is a policy lever that costs the city nothing and could accelerate adoption.
The regulatory path is the part that scares people. Alternative methods sounds like a legal battle.
It's more bureaucratic than adversarial. You submit engineering calculations, often with peer review from an academic institution, demonstrating that your system meets the performance requirements of the code. The building official reviews it, may ask for additional testing or analysis, and eventually issues a permit. It's slow the first time because nobody has a template. But once the template exists, subsequent projects can reference the approved precedent.
So the first project is the hardest, and everything after that gets easier. That's how every new material system enters a market.
Precast concrete went through the same process in the nineteen fifties and sixties. Structural steel before that. Reinforced concrete before that. Every material we now consider standard was once an alternative method.
So if you're convinced, here's what you can actually do starting tomorrow.
First, visit a quarry. Jerusalem's stone quarries are mostly in the hills to the west and north of the city. Talk to them about their cutting capabilities, their waste rates, and whether they've ever been asked about structural blocks. You might be surprised — some of them cut dimensional stone for restoration projects and have equipment that could be adapted.
Second, read the case studies. The Webb Yates projects in London, the Swiss residential building, the French vaulted hall. The Architectural Record and Metropolis articles are publicly available and they contain enough technical detail to start a conversation with an engineer.
Third, find your engineer. Not a general structural engineer who'll nod politely and design you a concrete frame with stone cladding — someone who's interested in the problem. Show them the case studies. Ask them what it would take to do a small structural stone project under Israel's building code.
Fourth, identify a client with a long time horizon. A university, a religious institution, a municipality, a family building a multi-generational home. Someone who cares what the building looks like and how it performs in fifty years.
The construction industry resists unfamiliar methods, as Hannah said. But it also follows demand. If a credible client with a budget wants a structural stone building, the industry will figure out how to deliver it. The engineers, contractors, and quarry operators exist. They just need a reason to coordinate.
The steelman here — and I think this is the honest objection — is that the ten to twenty percent cost premium is real, and in a housing market that's already unaffordable, adding cost for a five-hundred-year lifespan when most buyers are stretched to afford anything at all feels almost decadent.
That's fair. If the choice is between a concrete building that houses people now and a stone building that houses fewer people at higher cost, you build the concrete building. But that's not the actual choice in most of Jerusalem's construction market. The stone cladding mandate already adds cost — we're already paying a premium for the look of stone. The question is whether we redirect that premium into structure instead of veneer. And for institutional buildings, the lifespan math is unanswerable. A university that builds a concrete dormitory will rebuild it in two generations. A university that builds a stone dormitory won't.
The other piece is that as carbon regulations tighten — and they will — the embodied carbon of concrete becomes a liability. The eighty percent reduction stops being a nice-to-have and becomes a compliance requirement. The early adopters who've figured out structural stone by then will have a competitive advantage.
Which is why documenting the pilot project matters. Publish the cost data, the construction schedule, the energy performance, the seismic analysis. Make it available to other engineers and developers. The faster the knowledge spreads, the faster the cost premium shrinks.
The open question I'm left with is this: if stone can last five hundred years and concrete only fifty, why is our definition of sustainable so short-sighted? We talk about green buildings in terms of operational energy — heating and cooling — but we ignore the fact that we're building them out of materials that will be landfill in half a century.
The sustainability conversation has been captured by operational efficiency because it's easier to measure and regulate. Embodied carbon is harder to quantify and the benefits accrue over timescales that don't fit into political terms or developer pro formas. But the Metropolis lifecycle numbers are clear — the upfront carbon savings from switching to structural stone dwarf decades of operational efficiency gains.
If you're building in Jerusalem and want to explore this, send us your questions. We'll dig into the specifics — quarry contacts, engineer referrals, whatever we can find. This is a conversation worth having locally, not just in architectural magazines.
If anyone listening has worked on a structural stone project, anywhere in the world, we want to hear from you. The knowledge is scattered and every data point helps.
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