Tree Forks As Natural Composite Joints In Architecture

A problem facing architects when designing complex three-dimensional structures lies in their joints, which must be strong enough to take the loads and vector forces applied by the structure, yet light enough not to dominate it. Many efforts have been made to use generative design techniques or clever composites to fabricate them, but as Dezeen reports, a team at MIT are exploring an unexpected alternative in the form of naturally occurring tree forks.

The point at which a tree branch forks from its trunk is a natural composite material formed of an interlocking mesh of wood grain fibres. Timber processors discard these parts of the tree as they interfere with the production of smooth timber, but the same properties that make them support the weight of a branch are it seems perfect for the architects’ needs.

The clever part of the MIT team’s work lies in scanning and cataloguing a library of forks, allowing them to be matched from the database to vertices in an architectural design. The forks are subject to minimal machining before being incorporated into the structure, and to prove it the MIT folks have made a test structure. It’s not uncommon to see medieval barns or half-timbered houses using curved pieces of wood in their natural shapes, so it’s not surprising to see that this 21st century innovation isn’t an entirely new technique.

28 thoughts on “Tree Forks As Natural Composite Joints In Architecture

    1. Anachronistically Jenny has helped build a RobotWars robot in a Cruck-framed house.

      Wind-braces in such buildings were also made of more extremely curved wood than crucks.

      And if you watch “Acorn to Arabella” they are building the boat with “grown knees” cut out of the roots of tree stumps.
      (the last one is actually fitted in the very latest video)

  1. I saw a documentary on TV that mentioned the Vikings built their ships using wood that was curved during growth, rather than curving straight wood. As curvature of each plank was natural, there was less warpage in situ.

    1. They also split (rived) boards rather than sawed them so each board has the medullary rays running parallel to the face. That gives good stability and strength as well as flexibility.

  2. There was a documentary about the restoration of a wood framed ship named the Coronet. For one of the pieces they needed a big special piece of an oak tree and those types of oaks don’t grow anymore or were all chopped down to make said ships centuries ago. They petitioned the king of, I believe Denmark himself for permission to fell one tree from a protected forrest to use for the restoration. It was granted. I’m probably messing up some of the details but yeah. Amazing use of natural wood properties to make extremely strong structures. Solved by nature.

    1. IIRC the king of Denmark had those stands of Oaks planted about 400 years ago, for warships of the future. Foresight was both grand and dumb, at the same time.

      ‘Isn’t an entirely new technique’ that’s the nicest way of saying ‘being rediscovered by another generation of kids’ I’ve ever heard.

      The modern wood still doesn’t have the density of old growth. That has to grow under a mature stand of trees, hence growing slower.
      You don’t want to know what an aircraft grade, straight tight grain, real old growth piece of wood can cost. Just having the connection can be an issue. Laws schmaws.

      1. The palace of Versailles has an avenue that was explicitly planted for if Notre Dame needed a new roof at some point. Of cause they didn’t chop them down now that the roof burned down but that kind of thing isn’t that unusual.

      2. Yes I actually know what it cost ten years ago, having a need to replace rotted formers. I suspect it is even worse now. And the worlds yahoos have no plan to replace the materials

      3. Yeah, once you see real hardwood and do a wood turning on it up close (though not too close, because debris) you certainly realize that any ply sold in a big box store or even smaller hardware stores is probably going to be easily-warped, renewable hardwoods like pine. Hell, hardwood even makes for better garden mulch. Good luck finding Brazilian rosewood these days unless you got a spare kidney to sell.

        No one should ignore joints though especially with how crazy expensive that wood prices have become. Even when not in a joint design, a simple chainsaw / bandsaw job can make for a great turning piece or blank. And as you said, it’s more beautiful up close and even more so when you make something amazing out of it.

        I live in Texas and one thing I can say is that I am surprised more people aren’t trying to use red cedar or mesquite instead of these conifers they use for most (readily available) retail / builder-grade wood supply. These trees are generally considered pests here and grow (literally) like weeds and ranchers are largely happy to get rid of them. Cedar is also used a lot in “Native American flutes” as well (even if the tunings they use are nowhere near what the native peoples used and many suspect that with the current hole styling popular in the “Sound Healing” communities, the natives may have taken elements from their European invaders’ designs).

        You can still find good woods here but be prepared to have a horror-movie-weapon-of-choice handy and (as you mentioned) know the right person. Plenty of independent mills too, for the record, worth your business. Thanks to the Etsy/Ebay/Amazon era, woodspeople have learned the value of what they produce.

        With that in mind, I wonder how they are considering the fluctuation due to temperature over time – i saw shape and placement but nothing on temp which seems like an oversight or emission from the article. That’s the thing about wood which coincidentally also makes it great for acoustics – its molecular design is imperfect and not uniform and it is highly effected by its environment without proper finishing. That’s why tuning on those aforementioned flutes has to be done at an ambient temperature because the tune will literally warp as the temperature changes.

        One more point: commercial soft woods generally also require cheaper tools to machine than hardwoods. My Makerspace’s CNC router eats through pine like butter but I won’t try cheap bits on actual hardwood. And have fun drilling through vintage hardwood with a crappy modern drill press. I have seen videos of people using some beautiful sounding instruments made of mesquite. One day I will quit being a cheap skate and plunk down the cash for tools to work on this sort of material proper.

        1. Ok you think you have more information and are smarter than the MIT people.
          Soooo pine is a hardwood? Get over yourself, let the real engineers do the math and the hard work.

          1. Yeah the guy that’s been converting plans to structures for 20 years probably has more information than some grad students. Engineers that ignore the advice and criticisms of the people that have to deal with their designs are not engineers, they are design software operators.

        2. I have a friend who builds guitars. He is in his 70s now. Had built for several famous musicians. He has Brazilian rosewood and several other old extremely rare woods. He had the foresite 50 years ago to travel the world and select trees to have cut shipped to the US and cut and cured to his specs. Carl Barney is his name. You can Google him and learn a few interesting facts.

    1. Shipbuilders would definitely be strong but they wouldn’t be like Superman or anything because that work is done over time and your body gets used to a certain amount of work after a while. Even professional weightlifters have to deal with plateauing where they just can’t get any stronger and have to push way past their limits to break through that plateau to get their body building more and stronger muscle again.

  3. Tree branches are rarely stationary, so an idea I had many years ago, was to have peizo generators embedded at forks, the tree grows around it so to speak, forests generating power.

    1. i wonder how much power a tree could generate using the natural sway in the wind. ie: tie a rope off to the top, then attach each opposite end to a pulley maybe geared to a generator. it would be more torque than linear motion. just a thought as i sit here with my coffee and watch massive trees sway back and fourth in the breeze.

    2. Or going further out on a limb… things like those retractable USB cables strung across betwixt branch and trunk with a little dynamo in the hub.

      “Tree power” used to sort of be a thing, harnessed for reciprocating motion, for saws, pole lathes… though much of it was the spring in the branch rather than wind motion.

      1. Another branch of thought, Whale bone apparently has peizo properties, could it be possible that some trees also have or be induced to have such properties, peizo flags or ribbons are also a thing, wind pushes the limb, which springs back.

  4. It’s interesting to see this coming back around again.

    Architecture both terrestrial and nautical relied upon skilled ship- and house-wrights to find and use those naturally-grown crooks and bends to enable incredibly strong, centuries-durable, and remarkably flexible engineering in ships and buildings.

    In the 20th Century, shipbuilding changed to emphasize steel, and terrestrial architecture did also. While *residential* building practice still used wood, the techniques moved from timber-framing which required much more skill (but less lumber!) to balloon framing and then to platform framing (which does not require lumber quite as long)

    There are many reasons for the building changes in residential construction, but primarily this was about cost: a skilled housewright was harder to find, and more expensive to hire, and the large timbers and their joinery took longer to procure and produce than the kinds of joinery a carpenter uses in platform framing.

    But while the houses go up faster and labor costs are lower, they certainly don’t last as long, aren’t as strong, and actually use more board-feet (a volumetric measurement, which is confusing, I know) of lumber to build..

  5. While it would take years I suppose you could grow relatively uniform and standardized tree forks by using bonsai techniques on larger trees in a plantation.

  6. I seem to recall a description of how bronze age carpenters would find a suitably forked piece of wood to form the handle for making an adze, with a suitable bronze cutting edge inserted

  7. As a 65 year old boatbuider yes we would use roots and natural curves for strength but walking around the forests now even in my short lifetime you’ll be sadly singing “where have all the good times gone”
    Generational old growth forests are dependent on just that having the old dudes make the young trees grow straight and strong to get to the sunlight

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