Blending the Best of Old and New: The Future of Efficient & Durable Architecture

Words: Austin Tunnell

Words: Austin Tunnell, The Building Culture Playbook
Photos: The Building Culture Playbook

https://youtu.be/m6q64w2Orec?feature=shared
Editors Note: The original article can be seen here on The Building Culture Playbook

Over the past decade I’ve built a vertically-integrated real estate development company from the ground up.  I left my CPA career in 2012 for the Peace Corps in search of meaning and adventure.  I stumbled into inspiration, which has since developed into a lifelong mission: building a thriving world for people.

This journey began with a two-year apprenticeship of hard labor laying brick for a master builder.  Fast forward 9 years and Building Culture is an award-winning design + build company with exceptional emerging talent and a growing team.  I’m now working on the last piece of the puzzle: syndicating and sponsoring our own developments—our first of which is a $33MM urban neighborhood slated to break ground late 2024.  

Join me in real time as we pioneer a new way to approach development, fusing the liberal arts with construction and real estate to build a more beautiful, resilient, and thriving world for people. I’m glad to have you along for the ride!  Cheers to building a richer life and a better world.

Segovia, Spain, and the nearly 2,000 year old Roman aqueduct that was still in use until the 1970’s.

Last summer I spent a couple weeks in Segovia, Spain, studying historic masonry structures with some of the top experts in the world.  One of those professors I met, Philippe Block, a pioneering structural engineer and inventor, has shifted my perspective about concrete — one of the most widely used materials on planet earth — and how to think about it.

Years ago, I’d already moved away from the purist idea that everything should be “a traditional brick wall,” and shifted my language from saying “load bearing brick masonry” to “masonry-based construction systems” in terms of what we, at Building Culture, advocate for.

That is, using masonry, brick or stone, as the structure of a building as it has been used for thousands of years, and not just a siding held up by a wood or steel structure behind it, as is the case for the past 100 years.

Left: Solid triple wythe brick wall (load bearing brick masonry—the masonry IS the structure). Right: wood frame structure + single wythe brick veneer attached via metal ties.

I can promise you this: if the Roman aqueduct had been built with a wood or steel structure behind it, or even reinforced concrete with a stone veneer, it would have been destroyed within a few centuries of building it, probably less. Instead, they just stacked solid stones—that’s it—and it has persisted for 2,000 years.

But within that initial paradigm shift of me being open to various forms of structural masonry and not just “the traditional triple wythe brick wall”, I hadn’t fully come around to concrete, as so much of the concrete used today is destructive and used poorly. 

We use what’s called “reinforced concrete”: loads of steel rebar encased in concrete.  It’s extraordinarily strong — you can drive heavy vehicles across it.  The problem?  Concrete is porous and steel rusts.  When steel rusts, it expands up to TEN times its original size — which destroys the concrete.

It’s a strong, but vulnerable system.

Degrading steel reinforced concrete. The concrete has broken away from the steel and will further accelerate rusting and self-destruction.

I say this often: failing infrastructure in America isn’t failing concrete, it’s failing steel. 

Even though we now use epoxy coated rebar in big infrastructure projects, I’m still not big on embedding a ticking time bomb into our infrastructure that we could be building to last multiple centuries instead.  We should be solving for long-term resilience over pure strength.  But hey, it increases GDP when it crumbles and we have to rebuild ….

Also, remember that horrible condo building collapse in Florida in 2021?  Failing rebar.

But concrete, like stone or brick, doesn’t have tensile strength – it works in compression.  You can theoretically stack brick thousands of feet high before failing in compression (starts to crush itself under its own weight), but cantilever a single brick 4” from a wall, put weight on it, and the brick will break off easily.  It wants to work with gravity.

So that’s exactly why people put steel in concrete!  To add tensile strength and span large distances.  You can’t embed rebar into stone or brick in the same way because it’s solid, but with concrete you can form it up, lay down grids of steel rebar, and pour the wet concrete in. This is what it looks like to rely on steel and tensile strength to span horizontal distances:

Using steel to span horizontal distances

You might be wondering: so if brick and stone work in compression, how can they span large horizontal distances? The arch! You don’t need any steel or tensile strength when you use the right geometry.

Using geometry to span horizontal distances

The humble arch has been around for millennia.  And while I won’t get too technical here, the incredible thing about the arch is that it keeps everything in compression.  Remember when I said you could stack brick thousands of feet high before failing in compression?  Meaning a brick arch, entirely in compression, is incredibly strong. Or efficient is probably a better word.

Here is the single sentence Philippe Block uttered that fundamentally changed how I thought about concrete: Concrete is just artificial stone.  

While I suspected this was how to think about it, I’ve never seen concrete used in this way in the context of traditional building systems.  Modern engineers only usereinforced concrete, and traditionalists generally despise concrete altogether. Every expert I’ve met has been on one side or the other.  

Until Philippe. But the moment he said this, it all clicked into place.  

If concrete is really interchangeable with stone or brick, then it follows that the natural form of concrete to span openings is also the arch. There is no need for steel.  You just need the right form.

The implications of this are shocking.  Rather than 2 feet of this for a floor system:

Typical steel reinforced concrete floor system

You can just add a little curvature to it, get rid of 70% of the concrete and 90% of the steel (except for some external tie bars to resist thrust – depending on set up), and do this instead:

Philippe’s Rippmann floor system. Look how thin it is!

Why is this a big deal?  Well, a lot of reasons that I’m interested in, but I’ll give you one of Philippe’s examples: floor systems in commercial buildings are a huge part of the material, labor, cost, weight, and carbon emissions of the entire building. 

On a 25-story mid-rise, if you swap out conventional reinforced concrete floor systems with one of the unreinforced systems Philippe has pioneered, it saves 1200 concrete trucks and 20km of steel in the floor system alone.  That’s before accounting for the reduced weight and implications on the piers and foundation. This is unbelievable.

Also, conventional concrete floor systems are extraordinarily heavy, and often kill people in earthquakes or fires.  The twin towers collapsed straight down in a pancaking process as the floor system failed, up high, and began falling on each other in succession.  

Would one of Phillipe’s floor systems have prevented a total collapse?  I have no idea. But I’m pointing out that they are 80%+ lighter, and it certainly seems possible that a collapse of a few of those floor systems may not have led to a collapse of the whole building, as the lower floor systems could have supported the 80% lighter falling debris.  Just a theory from a non-engineer.

Philippe also introduced me to Graphic Statics and the concept of strength through geometry – the ability to design hyper-efficient structures by only putting the material where you need it, enabled by understanding the flow of forces through a structure. 

Remarkably, this isn’t new technology, though Phillipe is certainly innovating and building off of this millennia-old knowledge.  Check out the King’s College fan vault (500+ years old) compared to Philippe’s floor system.

King’s College, UK

Versus this. See the resemblance?

Philippe’s Rippmann Floor System. See video here.

Pretty cool, right?

Or take the Pantheon, a 2,000 year old, unreinforced concrete dome that’s still standing.

There is a ton more to say, but here is how I’ve updated my thinking:

  1. Unreinforced concrete is a viable, discrete masonry unit interchangeable with stone or brick—but can be formed into all kinds of unique shapes due to coming in liquid form and hardening through hydration.  This opens up all kinds of possibilities, and has immediate implications at Building Culture.
  2. The next evolution of “mass wall masonry” may very well be to reduce the mass for lighter and more efficient structures – which also happens to bring down costs, materials and carbon.  Mastery of something is very often tied to increased efficiency – that is, doing away with everything that isn’t necessary.  The fastest runners, for example, learn to limit any extra movement so that everything is in service of running faster.  They only make movements that are necessary.  The same can be applied to “mastery of masonry,” I think.  This is a whole new world for us to explore at Building Culture, and I’m stoked.


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