Hempcrete

[Brennan Oleary]

Has anyone ever used a hub-less wood geodesic frame to support a layer of precast hempcrete? Hempcrete affixed to the outside of the frame. 

Brennan

[Dx G]

I believe American Ingenuity in Florida build domes on a wood frame that was covered with concrete and stucco.  If hempcrete is not more dense than concrete, it may work fine if the dome is build properly.  If you look, you may find photos or drawings of their domes, as they closed up several years ago and the aidomes.com site seems to be something else now. 

Dx G

[Eric Marceau]

Hello Brennan,

Maybe offer an image of the kind of "hub-less" joint that you are planning to use.

Do you plan to build pre-assembled triangles that mate with other pre-assembled triangles?

per this example

Or are you planning to build using single beams for each triangular element on the geodesic?

per this second example (without the indicated hubs)

In both cases, not having any kind of alignment guide (hub for lack of a better word) is a sure way for the joining being mis-aligned, without mentioning that it likely would increase the assembly time caused by efforts to keep elements properly aligned.

Eric

On 2025-04-03 01:01, Brennan Oleary wrote:

Has anyone ever used a hub-less wood geodesic frame to support a layer of precast hempcrete? Hempcrete affixed to the outside of the frame. 

Brennan

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[Ashok Mathur]

Hello Brennan

An institution that I am associated with covers the frame with  a layer of ferrocement. That layer is about one inch thick. 

That way besides the geodesic strength, the structure also gets strength from its thin shell shape.

To me, hempcrete sounds very similar to Ferrocement with reinforcing fibre buried inside the cement.

Regards

Ashok

To view this discussion visit https://groups.google.com/d/msgid/geodesichelp/38c966ce-693f-4cd8-b22f-5dd19e40682a%40gmail.com.

[Brennan Oleary]

I watched a video where they used a kit from aidomes. It looks like some kind of foam triangles that are much lighter than concrete or even aircrete. Not really what I have in mind. I want to use the strength of a geodesic dome to support hempcrete, at ~20lbs per sqft it is far lighter than concrete.

The wood frame would be entirely inside the hempcrete and therefore completely protected from exterior moisture. 

[Brennan Oleary]

That sounds like a great way to enclose the frame. I have a friend who has worked with ferrocement. In my case, I want the structure to be semi-permanent, so I want to be able to disassemble the hempcrete and the frame. 

In a way, the hemp is like a reinforcing fibre, but hempcrete is not structurally very strong. Hempcrete's main strengths are its insulation value and moisture regulation. 

[Ashok Mathur]

Dear Brennanre

A gave a lot of thought to fabricating a very big dome in India in terms of struts and shipping it to USA for final assembly there.

You are interested in doing the reverse ie break up an assembled dome into parts for easy dismantling it.

I I found that thinking in terms of individual triangles of the dome does not lead to an easy solution as alternate triangle has only two sides with the third side being found in the opposite triangle. You end up with 50% of the triangles, having all the sides and 50% with one side missing.

With clever thinking this 50-50 divide can be pushed a little more in One Direction, but triangles with only two sides are inherently unstable.

I found that if we take out the pentagonal sets as complete eye, all the internal struts And external starts are retained intact, then the pentagon is quite stable.

The remaining triangles are taken out in terms of hexagons with all internal struts intact, and three external struts Missing. This is still quite stable.

In case Of hexagons that touch the ground. The number of triangles will be four, but that is an easy problem to solve..

I hope this helps you in some way.

Regards

Ashok

To view this discussion visit https://groups.google.com/d/msgid/geodesichelp/3c48b244-e2a7-4904-9973-f6a3b9435f0bn%40googlegroups.com.

[Brennan Oleary]

Assembling triangles to screw together, actually I am going to use bolts for additional strength and easier disassembly. 

[Brennan Oleary]

From what I can tell, Paul Robinson and Trillium build hub-less wood domes. Eric, are you saying that their technique makes it challenging to get alignment?

To view this discussion visit https://groups.google.com/d/msgid/geodesichelp/865120a2-ef14-4d41-8ac0-2b386e8e894fn%40googlegroups.com.

[Eric Marceau]

Instinctively, Brennan, yes!

Without some kind of hub-like alignment tool, you have to resort to multiple clamping tools for aligning triangle edges.  Given the variability in "true-ness" of the "2x4-like" members that form each triangle, mis-alignments creep in when dealing with wood construction.  That's a simple fact of life for such materials, although tight controls on source materials can reduce the introduction of those errors.

The key to the strength of geodesic construction is the integrity of the "joint's/hub's" ability for "aligned" force transfer ... and that depends on ensuring the vertex joints are indeed correctly aligned.

Just making sure such things are not overlooked.

I wish you the best with your project!

Eric

To view this discussion visit https://groups.google.com/d/msgid/geodesichelp/CANPiZmOTxw_Zu3G2k--n1TAVuaoRmPWsO91ebEpKgvujbMhxMA%40mail.gmail.com.

[Brennan Oleary]

Thank you Eric for your advice. 

I expect that aligning all that wood will be challenging. When you say it is a "sure" way for mis-alignment, I assume you mean there will inevitably be some misalignment given the amount of joinery. And that will compromise the integrity of the structure compared to a hub. 

I would like to start a business building these so I am more concerned about the labor than the skill requirement. I think a motivated worker could master the art quick enough, and if it is ~two days work for a 3v dome (16 man hours x $30/hr) then that might be better than paying $1000 for hubs. I need to look carefully at both options.

Can you point me to anyone who could help me understand the strength differences? Trillium domes claims their hub-less designs can support a minimum of 200 per square foot. 

To view this discussion visit https://groups.google.com/d/msgid/geodesichelp/04f0e79b-1628-4630-8f56-197cca1dcb49%40gmail.com.

[Dx G]

Brennan,

I have a serious bias about becoming a human machine servicing a mechanical machine.  It's my own personal gig, but actually trying to be constructive about it.   Sure, if a person is building just one dome for themselves, its probably not a big deal.  Think about it.  If you count the number of "sticks" one needs to put a dome like that together, then consider that multiple cuts have to be made at both ends of every one of them, that's an awful lot of operations and handling for every dome built.  What I've been looking at is how one can make those compound cuts on large groups of those sticks with common wood shop equipment, so that dozens of properly cut pieces can be banged out more quickly and easily than doing each cut on each end of each part over and over again.   I suspect if you want to make any money, being able to manufacture and fabricate that way stands a much better chance of developing into a going concern.   Maybe you already have that figured out, but if not, consider if that approach will help you succeed, which I hope you do. 

Dx G

[Brennan Oleary]

I agree with you, it is a lot of labour. I have been watching Paul Robinson make triangles, and I have underestimated the workload. I would say it would take one person at 20-30 minutes per triangle. Have you figured out a way to cut multiple sticks at once?

I have some experience in mass manufacturing, where efficiency is gained by workers doing simple repetitive tasks, but a happy worker this does not make. This would probably cut production costs and increase accuracy, but it is seems like a hub system will be cheaper and deliver more reliable engineering.

Brennan

[Dx G]

Brennan,
 Yes indeed, when I posted my last message I was actually reminded of some of Paul,s videos which actually illustrate the issue very well. So I'm glad you see the connection without any prompting from me.  I admire hard workers, but often we need to learn to work smarter rather than harder. The guy has some very big assets and ideas to share (I'm still impressed with his Wanger) and it looks to me like he's figured out he has a lot more to share than spending hours and hours acting as a human saw machine.

Two parts of your question -
Yes, I do think I have identified some ways to mass produce struts with compound angles using common wood shop equipment. I'm in the process of testing several methods and comparing them, as I'm after the "easiest" way to do this. In particular, doing this with round profile like PVC pipe offers challenges you don't have with rectangular struts, and I'm not sure yet if my "bright ideas" will do the trick, preferably using the same setup as the one for rectangular struts.  When I take on endeavors like this, I am always reminded of what HL Menken said almost 100 years ago,
  For every complicated problem there is a simple answer that won't work.

Second, I have been quite preoccupied with a Universal Strut Connector (UConn)  and posted about it.  You may find this interesting.  My post of March 1 (see 2a in subject line) has some important details.  I also believe that the Uconn concept can be applied to storm ravaged places in urgent need of emergency housing.  People see the piles of storm debris as "junk" that needs to be removed, but until they have better shelter, I see domes in them-there piles.

https://groups.google.com/g/geodesichelp/c/WVNShxVRr0c/m/zEjsSCewCQAJ

Actually, I was specifically thinking of people like you when I started on this odyssey.  I believe that joining struts is a major impediment to the proliferation of domes (which I am eager to see happen).  When I look at hubs in the research literature, patents and for sale, IMHO, they all suffer from weaknesses addressed in that list of assets (additions, deletions and changes are always welcome, if you have any feedback on it).  So I agree with you, having the right hub entirely erases a lot of problems (which you are currently considering) that otherwise prevent people from moving ahead.  I think this has been going on for decades, and believe it may be a plug, that once removed, may open the pipeline or at least contribute vastly.    
  So, as I tell myself, ok big shot, if you are going to complain about what everybody else is offering, if you are so smart, why don't you offer something better?  So I've been working on it. An early mock up of one of them is sitting in my work room right now, and I intend to load test it to breakage and see what it can stand before failure. I've been doing R&D, prototyping and product evaluation for decades, and prefer to be my own worst critic.  If I do release something, I want it to have a realistic chance of satisfying as many of those items in the list as possible, and perhaps providing a real gateway to converting interested people like you into a success in the dome industry.  A UConn addresses a big problem, but it also offers us a huge opportunity.

  Given what is happening on the earth, we need this. So keep the faith.

Dx G

[Eric Marceau]

I have none.  Only gut instinct based on formal mechanical engineering training, but no civil engineering experience.

I will leave it to those with actual build experience to respond to your query on pointing to sources regarding studies on strength.  

Eric

To view this discussion visit https://groups.google.com/d/msgid/geodesichelp/CANPiZmO30YgWtFMDb2SM65hBmivMZPOT6mo9NrNCFTXfvR3f6w%40mail.gmail.com.

[Levente Likhanecz]

from the strut "chart" you can count the similar triangles (congruent triangles). but a home workshop miter i doubt faster with fastening accurately bunches of timbers together than quickly do one by one. 　

To view this discussion visit https://groups.google.com/d/msgid/geodesichelp/50eb23cb-1ff1-41de-a3d6-ac034c4afc3bn%40googlegroups.com.

[Brennan Oleary]

I am working on a way to get kids off their phones and into the real world where they can develop healthy social skills. This involves a novel concept for a community centre where kids can develop skills in: discussion, debate, design, and dance. A place for kids to dream about ideas and then build them and then have some fun, basically a maker centre like Noisebridge in San Francisco or Hacklab in Toronto, but for kids.

I think the design principles I am pursuing for the community centre can also be used to build affordable housing, aiming for $30/sq ft. Basically, no petrochemicals and made mostly of materials that will last for centuries. All wrapped up in a cooperative business model. 

I have read the thread on your connector. In fact, I was going to ask you about this. Is it too early to request permission for direct messages here? Also, this is the first Google group I have joined, actually the first such group on any platform:)

“Given what is happening on the earth, we need this. So keep the faith.“

I agree. 

Brennan

[Stéphane Brodu]

Hi Brennan,

About this matter <<I think the design principles I am pursuing for the community centre can also be used to build affordable housing, aiming for $30/sq ft. Basically, no petrochemicals and made mostly of materials that will last for centuries. All wrapped up in a cooperative business model. >>  Can you contact me? (stef...@gmail.com , whats app 1 418 828 1559  stefbrodu)

I'm looking to build a network of communities based on these three principles:
1) living and making decisions in circular architecture (I build zomes with natural materials as much as possible)
2) using collaborative governance based on relationships with oneself, others, and the self, conflict transformation, and agility
3) open-ended learning for children and adults

I'm looking for kindred spirits to share these reasons for being, take ownership of them, and advance them together, in parallel. 

Personally, I'm more dedicated to "living together."

The goal is to create communities based on these principles all over the world that will be interconnected through initiatory journeys by sailing, walking, cycling, etc.

SB

Ensemble, soyons qui nous sommes vraiment !

To view this discussion visit https://groups.google.com/d/msgid/geodesichelp/056f5ddb-38b3-4c1b-9c2f-8aae614a0061n%40googlegroups.com.

[Ashok Mathur]

Dear Borodu,

The advantage of a dome or a zome, less material used per unit of floor area, becomes visible only when the dome is 'large' in size.

This is because of domes with lesser radius, the clear height near the diameter is very much less.

If we designate useable area of a dome that gives a minimum head clearance of 7 feet, than many smaller domes will not be economical compared to rectangular structures !

Regards

Ashok

To view this discussion visit https://groups.google.com/d/msgid/geodesichelp/CAGZSUeSEqjSeOBCjhA39XxuPqTnkBAwCh4%3D0O2Vy2n05GOpcpg%40mail.gmail.com.

[Dick Fischbeck]

Hi Brennan 

This sounds a bit like a project Bucky worked on in 1970 in NYC with some gang kids.

http://www.letsremake.info/PDFs/charas001.pdf

To view this discussion visit https://groups.google.com/d/msgid/geodesichelp/056f5ddb-38b3-4c1b-9c2f-8aae614a0061n%40googlegroups.com.

[Erich Nolan Bertussi]

i am hoping to get the math done on a hex pent module wall system weird shaped lego.

i just need to spend some time with a master of the maths. 

nothing yet. hope scale model prototypes by summer? deff have hemp as an insulation material and fibrewood/plywood structural components that and bamboo... and i think we can grow both inside of geodome green houses too... 

once the math is done any single wall section could be made from anything so long the attachment point specs and size specs are followed is how i see it... 

super modular. is my hope... 

On Thu, 3 Apr 2025, 01:02 Brennan Oleary, <allhumans...@gmail.com> wrote:

Has anyone ever used a hub-less wood geodesic frame to support a layer of precast hempcrete? Hempcrete affixed to the outside of the frame. 

Brennan

[Brennan Oleary]

Hi Stéphane,

Thanks for sharing your work, it sounds like a great idea! 

I am still putting all the parts of my work together, so I am unsure at this point how I might collaborate with others who are working on similar projects, but I hope that will change soon. 

Brennan

[Brennan Oleary]

Hi Ashok,

I am sorry for the tardy reply. Forgive me, I am new to domes and not sure what you are suggesting. 

Brennan

[Brennan Oleary]

Hi Dick,

Thank you very much for sharing that. 

[Ashok Mathur]

Dear Brennan

Let me see if I can simplify what I am trying to convey by using the simplest structure - a simple icosahedron.

It has twenty equilateral triangles with 60 edges when the triangles are considered without any joining.

But the number of edges  in an icosahedrons are only 30 that is to say half of edges merge into each other.

Now consider the five triangle structure at the (apex) top of the icosahedron.

This a stable structure in itself and is repeated two times in the icosahedron.

Thus half of icosahedron can be subdivided into stable joined parts or what is called shallow caps among dome makers.

Each edge of the shallow cap forms a part of a hexagonal structure.

In this structure, the six inner triangles have at least two edges. Every other triangle has three edges and equally every other triangle has only two edges. This structure is only partially stable.

I hope this makes clear as what is meant by subdividing a dome into partial sub structures that are partially stable before/ after sub - assembly.

Regards

Ashok

 

Regards

Ashok

To view this discussion visit https://groups.google.com/d/msgid/geodesichelp/68287c82-6ea6-4f93-b56e-489356a5a1dan%40googlegroups.com.

[Paul Kranz]

Ashok: An edge-up icosa makes a nice dome, too.

Very high regards,

 

Paul C. Kranz, LMFT

Kranz & Associates, LLC

ReviveTheFlame.com

To view this discussion visit https://groups.google.com/d/msgid/geodesichelp/CAD-a3OiZaOOzsgZQWD2PCiK4v45H6bgoj4KEx9T3%3DgM8ikfLcA%40mail.gmail.com.

[Brennan Oleary]

Hi Ashok,

I have not looked into the geometry very much. Been focused on materials. I was just going to follow the dimensions of a dome calculator and assemble. Figured I would learn the geometry during the construction. 

I think I understand what you mean by a partially stable structure as I have seen Paul Robinson assembling those structures independently before putting them together into a dome. 

Aren't the dome calculators on Domerama all icosahedrons? 

In the 3V I am looking to build, the five triangle structure at the apex is repeated five more times, so I am confused when you say two times. 

Until I study the geometry or build a dome, I am lost without visuals. 

Brennan

 

To view this discussion visit https://groups.google.com/d/msgid/geodesichelp/CAD-a3OiZaOOzsgZQWD2PCiK4v45H6bgoj4KEx9T3%3DgM8ikfLcA%40mail.gmail.com.

[Ashok Mathur]

Dear Brennan

A sphere has six  vertices that are pentagonal with two vertices being diagonally opposite each other.

If the dome is deep, then the five structure gets repeated four times it in all five times the pentagon repeats itself.

If the dome is hallow, it may repeat only 3 more times.

What is important that you start thinking in terms of partially stable sub- assemblies.

Regards

Ashok

On Thu, 24 Apr 2025 at 8:41 PM, Brennan Oleary <allhumans...@gmail.com> wrote:

Hi Ashok,

I have not looked into the geometry cvery much. Been focused on materials. I was just going to follow the dimensions of a dome calculator and assemble. Figured I would learn the geometry during the construction. 

To view this discussion visit https://groups.google.com/d/msgid/geodesichelp/CANPiZmMSkJ%2BQrcTZbSgXK3Q3ksTf-ojg7ucTUQsYVkz%3Dk0KSUA%40mail.gmail.com.

[Brennan Oleary]

Thank you for all your advice Ashok, I will prioritize sub-assemblies. And dig into the geometry:)

[Ashok Mathur]

You are welcome.

Regards

Ashok

To view this discussion visit https://groups.google.com/d/msgid/geodesichelp/17d9b090-9a91-4ded-8323-2a27b97938f7n%40googlegroups.com.

[Brennan Oleary]

Hi Eric,

Sorry I missed your reply. Are you planning to use hemp batt insulation or hempcrete? 

Hope you find that master of maths, definitely not me haha

[Ashok Mathur]

Regards

Ashok