GrowDome 3

geodesic grow dome

This grow dome was surprisingly cheap to make and offers
about 15 cubic metres of protected growing space

This is the top half a two-frequency icosahedron. I chose to go for a much stronger and permanent structure and ordered tannelised garden two-by-one especially for the purpose, along with sand and cement to put in a ‘crazy paving’ base from my garden of rocks (on the edge of Bodmin Moor).

two frequency icosahedron

There were two strut sizes for the third dome, the image
above shows them cut and painted, along with the model

I can’t over-emphasise the importance of having a model to work to for dome building that has more than one strut length, otherwise it is easy to get lost in the structure. Marking the different struts helps too, I painted mine with some left-over wood treatment. I connected the struts using metal discs, pre-cut with metal cutting shears and drilled using a cardboard template. The discs  were made from a sheet of galvanized metal I found, and a sheet of corrugated galvanized roofing that seemed to have been flattened by a tractor.  The struts were just screwed onto the discs.

building a dome greenhouse

The top of the third dome, raised on tyres so that I could add
struts underneath and raise it up whilst building.

Connecting the struts and raising the dome up on tyres allowed me to connect new pieces to the underside. I had to give special attention to the joints at the top because they took additional strain during the construction. I bolted on plywood disks for support.
Piece by piece, it took shape and it became clear to me that a half-sphere dome would be easily tall enough rather than the five eighths dome I had intended to build. This was fine as it meant there was wood leftover for an inside structure.

grow dome anchored to ground

After my experience with the first dome blowing around, I
cemented this one firmly into the ground.

I dug holes under each of the strut nexus points at the base and put in some uprights to clear the plastic lining sections from the ground and allow me to build-in ventilation. I cemented these uprights in – making horizontal corrections with a spirit level as I went round. I used a mixture of techniques to fill-in these undergaps: engineering bricks, concrete and dog-food tins, old slates, carpet, bricks and blocks with cement (one side was next to the gas output of our septic tank and I certainly didn’t want methane build-ups in the dome).

Then the floor went in, like a mini patio made from all the flattish rocks and bits of slate I could get my hands on. I painted some of the rocks at the back black, and left them raised to absorb more heat from the sun.

geodesic grow dome

This is the third dome with the structure completed,
awaiting the final pieces of glazing

Finally, it was time to put on the polytunnel cover. I ordered another £30 worth because I intended to recycle the cover from the first dome into this one. This glazing part was quite laborious as I had to cut the sheeting into rough triangles, staple it onto the struts and then trim to size. It is best to work from the bottom up, then the rain will flow down, and not into, the dome due to the overlaps. Once I got to the top of the dome it got tricky and there was lots of stretching up a ladder. I had made one top triangle as a detachable window which helped with the top glazing and is essential for airflow. I also made a detachable window on one side for wheelbarrow access. All the overlaps were then sealed using a waterproof tape made for polytunnels. I made a door by taking out a cross strut and putting in hazel sticks which pushed the space open so as not to weaken the structure. This has a porch from which I hang netting to keep out the ever-present blackbirds.

inside the geodesic grow dome

The interior of the third dome showing the built-in
bench with picking lettuce, squash and tomatoes

The first season I had a good crop of blueberries, picking salad, coriander absolutely loved the warmth in there, squashes, tomatoes, basil and peppers. Next growing season I will hopefully have time to concentrate more on the soil quality in my pots. All in all the wood, screws, plastic sheet, sand and cement cost me around £150, a great investment for a growdome which I hope should last five years at least.

Posted in Uncategorized | 2 Comments

Buckminster Fuller

This text was presented as a talk at the Sunrise Offgrid Festival August 2012:

Soap Bubble Sky from Wikimedia Commons

I offered to give a talk on Buckminster Fuller after Dan, an organiser for the festival, made an invitation on Facebook. Buckminster Fuller has certainly had an influence on my life and I wanted to share some of this with you. I discovered him for myself at art college when I started messing around with geodesic domes.

How many of you have heard of Buckminster Fuller?

Here is a well-known picture of him. One of the first things that occurred to me on seeing his pictures is that I thought he looked a bit like a tortoise. Now I liked tortoises a lot, here’s a picture of one I made out of clay when I was 10 years old.

buckminster-fullerActually sometimes I think I look a bit like a tortoise too, so I was happy to find Buckminster Fuller because I knew I wasn’t the only person in the world who looked a bit like a tortoise.

TortoiseBuckminster Fuller was born on 12th July 1895 and lived for 88 years. Some people claim him to be one of the greatest thinkers of the 20th Century. At art college I even read one of his books called ‘Critical Path’.

Critical Path

It wasn’t an easy read, but nestling there in the middle was a secret that changed my life. It was what Buckminster Fuller called the ‘Law of  Precession’ and it was based on some of his observations, the results of which he lived his life by also. But I’m getting ahead of myself here – we’ll come to ‘Precession’ in a few minutes.

Times were pretty harsh in the early 1900’s and Buckminster Fuller lost a daughter to illness in circumstances that caused him to feel pretty bad about himself. According to history he was so unhappy he was even considering taking his own life. But a voice popped into his head and said: “your life is not yours to take.”

Now this stopped him dead in his tracks and resulted in him asking himself who owned his life, then possibly THE QUESTION: “What then, is the purpose of my life?”

He answered it for himself and resolved from that stage on to design and make things to solve global problems surrounding housing, shelter, transportation, education, energy, ecological destruction, and poverty, which he did for the rest of his life.

“I set about fifty-five years ago to see what a penniless, unknown human individual with a dependent wife and newborn child might be able to do effectively on behalf of all humanity…”

At this stage I would like us to look at some of the things he made:

Dymaxion CarDymaxion car:

In 1933 he presented his plans for the three-wheeled Dymaxion Car with rear steering and front-wheel drive powered by a Ford engine. The aerodynamic shape, most closely related to high performance yachts, came partly from Fuller’s co-designer, the shipbuilder Starling Burgess. The rave reviews of the car’s styling, speed and manoeuvrability were tragically undermined when the first of three prototypes was rammed and overturned, killing the driver, outside the entrance to the 1933 Chicago World’s Fair.

I can’t help thinking that the Dymaxion Car looks a little bit like a tortoise.

Dymaxion house:

Dymaxion SilosIn 1940, in anticipation of the bombing of British cities, he was asked by the British War Relief Organization to design an emergency shelter. Fuller worked with a grain silo manufacture, using curved galvanised steel to develop a self-supporting structure in a circular shape. The unit was designed to be set up and taken down easily. Metal for its construction was, however, never made available by the British Government as it was needed for the production of armaments. When the US entered World War II, Fuller’s units were commissioned as emergency accommodation for the air force.

These do look a little bit like tortoise shells though.

Dymaxion HouseThe development of this was called a Dymaxion House. Made from lightweight steel, duraluminium and plastic and suspended from a central mast from which the rooms radiated in a hexagonal plan, the Dymaxion House was conceived not as private property, but rather as temporary, transportable space that could be rented – rather like a telephone issued by a telephone company.

Does anyone think that this looks a bit like a big tortoise shell?

Fuller Projection Map

Dymaxion MapAlso known as the “Dymaxion Map,” this is the only flat map of the entire surface of the Earth which reveals our planet as one island in one ocean, without any visually obvious distortion of the relative shapes and sizes of the land areas, and without splitting any continents. It was developed by R. Buckminster Fuller who “By 1954, after working on the map for several decades,” finally realized a “satisfactory deck plan of the six and one half sextillion tons Spaceship Earth.”

“Our little Spaceship Earth is only eight thousand miles in diameter, which is almost a negligible dimension in the great vastness of space. . .

Spaceship Earth was so extraordinarily well invented and designed that to our knowledge humans have been on board it for two million years not even knowing that they were on board a ship.”

The Dymaxion World Map was his attempt to resolve the problem of how best to represent a spherical world on a flat surface, with true scale, true direction and correct configuration. In orthodox cartography to present one of these attributes accurately others must be distorted but The Dymaxion World Map’s distortions are distributed proportionally within each of its fourteen segments.

This map, unlike the ones we are used to, shows all the countries of the earth joined, as one. This was very much part of Fuller’s philosophy. Fuller also repeatedly makes it very clear that the scarcity paradigm that so many economists espouse is a thing of the past. This way of viewing the world no longer accurately describes the world.

He says that the past 100 years of history show that man has been able to consistently and constantly do more with less. The human ability to invent and use technology has made the world abundant. The problem lies not in man’s ingenuity and inventiveness but in man’s greed. For man constantly makes the world scarce through war and greed. That is why so many people starve and suffer.

In a nutshell he is saying we can innovate ourselves out of scarcity. Although this isn’t the ‘whole picture’ thesedays, his ideas make a lot of sense to me. We only lose our energy in fighting ‘the system out there’ and we will never change it much. And we all know its days are numbered or we wouldn’t be here at this Offgrid Festival. Much better is to spend our time making new systems that work for us and people like us. If they work – other people will adopt them.

 “You never change things by fighting the existing reality. To change something, build a new model that makes the existing model obsolete.”

Fuller believed in having the courage to stand up for truth rather than simply following the course of least resistance. He calls people to unite and transcend to change the world around us. Since the ability to transform our world is in our hands, we have a tremendous responsibility to shape the world for the benefit of humanity and the good of others.

“Whether it is to be Utopia or Oblivion will be a touch-and-go relay race right up to the final moment. . .  Humanity is in ‘final exam’ as to whether or not it qualifies for continuance in Universe”

He invented a ‘game’ about this very thing.

World Peace GameThe World Game:

Buckminster Fuller was convinced that we could achieve a higher standard of living without anyone profiting at the expense of another so that everybody can enjoy the whole earth.

World Game, sometimes called the World Peace Game, is an educational simulation developed by in 1961 to help create solutions to overpopulation and the uneven distribution of global resources. This alternative to war games uses Fuller’s Dymaxion Map and requires a group of players to cooperatively solve a set of metaphorical scenarios, thus challenging the dominant nation-state perspective with a more wholistic “total world” view. The World Game that Fuller envisioned was to be a place where individuals or teams of people came and competed, or cooperated, to:

“Make the world work, for 100% of humanity, in the shortest possible time, through spontaneous cooperation, without ecological offense or the disadvantage of anyone.”

In 2001, a for-profit educational company named o.s. Earth, Inc. purchased the principal assets of the World Game Institute and has been offering a Global Simulation Workshop that is a ‘direct descendant of Buckminster Fuller’s famous World Game.’ In 2010, Filmmaker Chris Farina released a documentary on the World Game entitled ‘World Peace…and other 4th-grade achievements’. The film follows the life of 4th-grade teacher John Hunter and his utilization of the game in his classroom. Despite the challenge and the complexity of the game, the 9 and 10-year old students are able to win it and ‘Achieve World Peace’. The documentary was shown at the 2011 South by Southwest Music and Film Festival and has won audience awards at various international film festivals.

Geodesic domes

Early Geodesic DomesHis teaching colleagues and students in the 1950’s helped in the development of his most successful project, the geodesic dome, the first large scale versions of which were built at Black Mountain College.

Hailed at the time as the lightest, strongest and most cost-effective structure, the geodesic dome was designed to cover the maximum possible space without internal supports. The bigger it is, the lighter and stronger it becomes. The first full-size geodesic structure was completed – with a 49 feet diameter – in Montreal in 1950, the following year one was exhibited at the Museum of Modern Art, New York.

In 1954 Fuller constructed two domes at the Milan Triennale exhibition made from six pieces of corrugated cardboard pre-cut in the US and folded into a small packing case for transport to Italy. Fuller’s hope was that such domes could one day be manufactured at the rate of 3,000 a day.

  • applying modern technological know-how to shelter construction
  • making shelter more comfortable and efficient
  • making shelter more economically available to a greater number of people

UDomesThe U-dome from World Shelters adapts the modular geometry of Buckminster Fuller’s geodesic dome. U-domes have been used for disaster response, portable medical clinics, relief agency centers, temporary housing, storage, and workshops. The patterns can easily incorporate local materials, and they are re-usable.

By 1957 Fuller  had refined the design so that an enormous auditorium-sized geodesic dome was assembled in 22 hours in Honolulu. His plans for a 2 mile wide dome in Manhattan, 1960, never came to fruition but have remained the stuff of science fiction ever since. As you can see it looks like a huge tortoise shell because really, he wanted everyone to be tortoises.

IcosahedronMost domes are based on an icosahedron, which is spherical with 20 faces. This shape exists in nature, for example some viruses are icosahedrol. It is a very strong structural shape. The 20 triangles that make up the shape can be further subdivided into smaller triangles giving eg a two-frequency icosahedron, or three frequency icosahedron. There are many varieties of dome.

Cardboard icosahedronThe icosahedron above is made from thin card, with each face subdivided by triangles, showing different ‘frequencies’ of icosahedron. The home-made growing domes below show a basic icosahedron greenhouse made from hazel rod and polytunnel sheet, and a three-frequency icosahedron made from recycled plastic sheeting. Further information on making these is available at:

link to growdome websiteIcosahedron growdome1Growdome 2


‘Bucky’ was incredibly creative and before his time in many ways. Ideas and inventions seemed to flow from him in a continuous stream. I would urge you to have a closer look at some of his stuff online.

But back to his ‘Law of Precession’ which, for me at least, is the single greatest influence from his life. From ‘Critical Path’ and I promise it’s the only bit I am going to read:

“I assumed that humanity was designed to perform an important function in the Universe, a function it would discover only after an initially innocent by-trial-and-error-discovered phase of capability development.

During the initial phase humans, always  born naked, helpless and ignorant but with hunger, thirst and curiosity to drive them, have been chromosomically programmed to operate successfully only by means of the general biological inadvertencies of bumbling honey seeking [eg money making].

Therefore what humans called the side effects of their conscious drives in fact produced the main ecological effects of generalized technological regeneration. I therefore assumed that what humanity rated as ‘side effects’ are nature’s main effects. I adopted the precessional ‘side effects’ as my prime objective”.

Note he assumed that humanity has a purpose; we are here for a reason. This in itself is quite radical. We are not really told about this at school. Where, today do you hear people talking about a purpose for the human race? Out there, in the world of celebrity consumer capitalism, which we are all taking a little break from, the main purpose seems to be to wreck the planet by consuming everything and turning it into rubbish to put into big holes. To watch the telly and support the staus quo by not asking questions and turn expensive pre-packaged food, with its nutrition removed, into poo whilst engendering enough cancers to keep the big pharmaceutical industries in profit..

Buckminster Fuller believed that humanity has a purpose. He set out to make things that would help people to evolve, regardless sometimes of money, getting paid, having a job and all that. Most of his work was directed at helping solve problems that prevented people from being more self-sufficient. He committed not just himself but also his family to this course of action and lived, by all accounts, a very successful life in traditional terms as well as his own, at least once he started dressing more smartly and stopped being rude to people.

Let’s just look at some of his observations that led to his Law of Precession idea.

When you drop a stone into a lake – where do you see the effect?

precession examplesBuckminster Fuller liked bees. I don’t actually know if he liked tortoises. He watched them visiting flowers (bees not tortoises) and saw what was happening. The ‘evolutionary’ effect is happening at 90 degrees to the bee’s ‘purpose’ which is driven by nectar (and pollen). In collecting nectar the bee is, quite inadvertently, cross-pollinating the flower.

A similar example here – this Ancient Chinese puzzle. [Here I provided members of the audience with a Chinese Finger Puzzle to demonstrate how the pressure on the fingers is exerted at 90 degrees to the energy provided; at right angles.]

In a similar way the evident purpose of mankind in making war and pursuing material gain in the form of money, actually has a secondary purpose in ‘evolutionary terms’. So metal created to make weapons became used to make ploughs that farm the land to create food. The Internet, designed originally for the purposes of war, has become endless networks of people leading to the democratisation of knowledge, for those people lucky enough to have access.

So for me the western ‘story’ of: get a job, make enough money to get a mortgage, work your whole life through to get a pension, is failing dramatically. Buckminster Fuller offers us a credible replacement to that story and his life stands in tribute to it.

“The youth of today are absolutely right in recognizing this nonsense of earning a living. We keep inventing jobs because of this false idea that everybody has to be employed at some kind of drudgery because, according to Malthusian-Darwinian theory, he must justify his right to exist.

The true business of people should be to go back to school and think about whatever it was they were thinking about before somebody came along and told them they had to earn a living”.

According to Fuller, start working directly for the evolution of people, planet, universe around you and you will find yourself mysteriously ‘looked after’ by those same forces. Almost never in the ways you expect, always seemingly at the last minute.

Natural sciences are still catching up with the significance of his discoveries. In some cases recognition of the importance of Fuller’s scientific research came only after his death. By then he had registered 25 US patents, written 28 books, traveled around the globe 57 times and received 47 honourary doctorates as well as numerous other awards including a 1969 nomination for the Nobel Peace Prize.

Here’s a picture of Bucky and me on holiday in the Seychelles:

Tortoise loveAs someone who dislikes many of the aspects of capitalism, the sheer faith this guy had was quite stunning. I have always tried to follow this ideal and when I find myself broke, I console and motivate myself by thinking that I may not be serving the processes of evolution quite as well as I could.

Posted in Uncategorized | Leave a comment

Greenhouse from plastic bottles

Re-purposing plastic bottles and saving valuable resources from landfill is important environmental work. The picture below shows school children from Mill Lane School in Chinnor, Oxfordshire, who collected 1,500 plastic bottles over 18 months in order to construct their greenhouse.

plastic bottle greenhouse

greenhouse of plastic bottles

Children from Inveravon Primary School and Rothiemay Primary School have gone even further and provide a free download with instruction on: ‘How to build your own Recycled Plastic Bottle Greenhouse

Posted in Uncategorized | Leave a comment

Hazel Polytunnel

I know its very rude of me but I have lost the contact details of the lady who so kindly sent me the pictures of her polytunnel below. These demonstrate clearly the flexibility of fresh hazel when used in construction.

hazel polytunnel

polytunnel made with hazel

inside hazel polytunnel

Inside the hazel polytunnel

 I have also seen small-bore, plastic drainage pipe and open metal ‘mesh’ used to hold a polytunnel to shape, but definately prefer the hazel as it is not oil derived or using polluting industrial processes to manufacture. Now if only there was a natural alternative to polytunnel lining itself. (OK – glass – but very hard to integrate with natural structures):

Posted in Uncategorized | Leave a comment

GeoDome-Northern Homestead

This dome is a real beauty although the wood cutting might take some time. I particularly like the way the builders, Jakob and Anna Esau, have eliminated the need for connectors by jointing the struts directly.


Northern Homestead GeoDome

From their website: “When it comes to gardening in colder climates, a greenhouse is almost a must have. It extends the growing season and gives the plants a lot more heat. With a greenhouse, we can actually pick ripe tomatoes here and grow some plants that we would not be able to without one. A greenhouse can also be a great place to hang out on those cool spring days and summer nights. When we started to look out for one to build, our expectations were very high. In a northern garden we have to deal with frost, nasty winds and hail, and also loads of snow in the winter. Our days in spring and fall don’t have much direct sunlight so we need to catch every sunbeam we can. Plus, we live in town and the greenhouse in our small back yard needed to be somehow catchy. In our research we came across the GeoDome greenhouse:”

The builders have provided extensive information on how to make this dome and you will even find a free ‘how to’ ebook on their site at:

Posted in Uncategorized | Leave a comment

Making growing dome 2

A five-eighths, three-frequency icosahedron greenhouse for £30

A DIY dome greenhouse

A DIY dome greenhouse

Here is the completed dome, covered with polythene, bubblewrap, old tent, large dog-food bags and industrial clingfilm, mostly from recycled sources.

Growing inside the greenhouse dome

Growing inside the greenhouse dome

Currently it is growing melons, squash, cucumber and basil. On a sunny afternoon I have seen the temperature inside at 46 degrees plus.

Tools for the dome construction

Tools for the dome construction

Putting the pieces together

Putting the pieces together

I used a small brick, acrylic filler gun and stapler to fix the struts inside the connectors The first bit was easy but it soon

Pulling my hair out stage

Pulling my hair out stage

Starting to take shape

Starting to take shape

turned into a jumble of sticks that had me pulling my hair out. Once I started using supports stuck into the ground the dome stopped moving around and I began to see the shape

My knees got grass stains

My knees got grass stains

Oh I can see it now!

Oh I can see it now!

Crawling in and out of the triangles was certainly good exercise Finally the basic geodesic structure was complete

Then I had to move it!

Then I had to move it!

The covered dome nestles in tranquility

The covered dome nestles in tranquility

But then I had to move it to another part of the garden. The ‘roof’ needed additional support and I lashed more bits of bamboo to the structure at the top. I used all of the old polythene and bubblewrap I could find around the place, stapling it onto the struts. I also left a window in the roof to decrease humidity.

I put the greenhouse dome on top of some old slabs of concrete from a garage and these seem to work superbly as a heat sink. Since the structure sags slightly under its own weight, due to the flexibility in the hosepipe connectors, I wrapped it round the middle with several layers of industrial cling film for support, this seems to have done the trick.

It is certainly warmer in there than in our more traditional greenhouse. I realise this is a ‘bender’ of a greenhouse, but as this section of the garden is not overlooked it is perfectly acceptable. At dusk it sometimes looks as if a spaceship has landed in the garden. The plants need watering pretty much every day and I have never harvested so much basil in my life. I am very excited about my first melon.

My first home-grown melon

My first home-grown melon

Now it is a bit of a leap from a simple icosahedron to a 3 frequency, and in some ways I wish I had made this one as a 2 frequency dome – it did take a lot of time to make (and move) the structure. So for my next geodesic DIY greenhouse I want to make a 2 frequency dome with a more rigid framework.

Posted in Uncategorized | Tagged , , , , , | 2 Comments

Materials for growdome2

Materials for a 3 metre, three frequency, five eighths icosahedron

I wanted to make a greenhouse growing dome using recycled materials as much as possible.The main expense for this growing dome was the bamboo. I bought 100 seven foot sticks as these had the best diameter to fit inside the recycled hosepipe. I bought some mixed colours of electrical insulation tape and five tubes of acrylic filler to wedge the smaller bamboo sticks inside the hosepipe.

I made the mistake of buying a very cheap stapler which kept exploding, nearly taking my eye out one time and then narrowly missing a window. The better one I purchased was certainly showing signs of wear by the time I got the plastic sheeting stapled onto the dome. All in all, once again I spent about £30 on materials.

Preparing the workbench

Preparing the workbench

The struts cut and stacked

The struts cut and stacked

The first job was to saw all of the struts to size. I worked out the sums (see previous article) and laid out masking tape to size on a work surface to save measuring every piece. After a while I had my struts cut to size and colour coded, stacked into containers.

Chamfering the ends

Chamfering the ends

Leaky old hosepipe

Leaky old hosepipe

Some of the struts were too bulbous to fit inside the hosepipe so I chamfered the ends down using a plane Next – onto the hosepipe. This was leaky old hose that had been hanging round in the garden for ages and I was too mean to throw it away (as if there is an away!). I cut it up into about six inch lengths by eye.

Making the connectors

Making the connectors

Bending the nail

Bending the nail

I stuck a flat headed roofing nail through 3 pieces of the pipe to make the connections – for this dome most of the connections would use all 6 arms – but some only used 5, leaving a piece hanging Then holding the connection, and the nailhead, firmly with ‘universal grip’, quick release pliers, I hammered the nail over to join the pieces.

A pile of growdome connectors

A pile of growdome connectors

Premade 'C' sections

Premade 'C' sections

Before long ( a few hours) I had the connectors I needed. I premade the ‘C’ shapes for the 3 frequency isocahedron (see previous article)

I had all the tools and materials I needed to put the dome together but it was some time before I got round to doing this. I started twice but inclement weather and pressure of work prevented me from concentrating. What comes next is a very complicated three dimensional jigsaw and I strongly recommend building a colour coded model before embarking on the next stage.

Posted in Uncategorized | Tagged , , , , | Leave a comment

A 3 frequency model dome

With a large 3 frequency dome its important to build a model to follow as things can get complicated. I had made one of these before using straws and sticky-back plastic so got myself loaded up with straws from a supermarket. All the straws I could find had stretchy bits near the top so I cut one to find a maximum strut length I could use. To cut a long story short I came up with a dome radius 35.25 cm for my model.

If you have seen the basic guide to making a model icosahedron you will see it is made up of 20 faces. In a two-frequency dome, each strut length is subdivided by two, creating 4 equilateral triangles on each face.

For the 3 frequency icosahedron each strut length is divided by 3, creating 9 triangles, made up of struts as shown in the diagram below.

2 and 3 frequency faces

2 and 3 frequency faces

In a 3 frequency icosahedron there are 3 chord factors ie three different strut lengths are required. If you get different coloured straws the model works as a useful reference for building full scale. The chord factors for a 3 frequency icosahedron are:

  • A = .3486
  • B = .4035
  • C = .4124

And that formula again: C (chord factor) x R (radius) = length of strut

My sums for the struts were:

  • A= 123mm x 60, colour blue
  • B= 142mm x 90, colour green
  • C= 146mm x 120, colour orange

It took me an hour and a half to cut these and pretty soon I had three piles of straws in front of me, waiting to be connected. I started by connecting the C nodes. I then started connecting the B and C struts, to make a single icosahedron face. Then I went into factory mode and made all of the C connections.

Building the first dome face

Building the first dome face

The dome model takes shape

The dome model takes shape

Bit by bit, the dome took shape and I used a camera tripod to hold the model in a rough dome shape to make all of the connections. Eventually, I had my model three frequency icosahedron.

Completing the 3 frequency icosahedron

Completing the 3 frequency icosahedron

Posted in Uncategorized | Tagged , , | 2 Comments

An icosahedron growing dome

Inside my growing dome

Inside my growing dome

The covering for this dome arrived the day after I had finished the frame – great timing. I  ordered 3 metres of 7.3 metre wide Sunmaster Tunnel Covers from Carters Packaging in Cornwall where I live. I cut oversize equilateral triangle sections and nailed them on with small, flat-head, roofing nails onto the framework, folding over the sheeting to produce a stronger edge. This is where the fresh-cut timber came into its own – as it was still sappy it took quite a lot of pounding without splitting at all. I’m not sure the same would be true of purchased 2×1, especially if it were old stock.

Three (oversize) equilateral triangles (eg ∆∆∆ – giving 5 triangles ) fitted the width of the poly sheet and allowed for anomalies created by the wild wood and the fold-over onto the struts. I later tidied-up these edges with a staple gun.

Home-made greenhouse

Home-made greenhouse

The grow dome worked very well in the spring, nearly all the seeds sprouted but there were a couple of problems. Firstly there was not enough ventilation and while the earth was damp inside the greenhouse it got extremely humid when the sun came out. Some of the seedlings didn’t like this at all. Leaving the ‘door’ open during the day helped but the greenhouse would benefit greatly from some kind of ventilation at the top which would also supply a hole where trapped insects could get out easily. Unfortunately, leaving the door open meant that one rainy day the polythyene filled with so much water the weight of it snapped the wood of the door frame – well, easily mended!

The flying greenhouse

The flying greenhouse

Secondly – the wind. I had fully intended to anchor the dome but didn’t get round to it – until it was too late. We get some pretty ferocious winds on the edge of Bodmin Moor in Cornwall and on one particularly windy day I heard a large ‘flapping noise’ coming from that part of the garden where I had put the icosahedron.

I went round the house to see that the dome had moved 25 feet, scattering all the tables full of seedlings across the garden like some kind of airplane wreck. It had landed the right way up and from the small rips in the polythene, made by table and chair legs, it appeared to have completed a somersault. It took myself and Sarah most of the afternoon to pot on all the seedlings and suitably humiliated I tied the dome down to some stakes hammered as far into the ground as I could get them.

grow dome with tomatoes

grow dome with tomatoes

The dome, apart from a couple of small rips, was completely unharmed and structurally sound. As I write this now it is full of tomatoes and the spring seeds are all out in the garden. For a while it housed my inflatable paddling pool which worked well as a solar heat sink, but I emptied it because there were some mosquito larvae in the water.

All in all this garden growing dome cost me £30 for the polytunnel covering – but I did have a stock of roofing nails and wire and rope in the garage.

My next project is to build one of these with every large triangle subdivided by three (eg nine trianges in each) – a ‘three-frequency, five eighths, alternate icosahedron’ – which is theoretically more of a dome shape.

Posted in Uncategorized | Tagged , , , , | 1 Comment

Building a DIY greenhouse

My first growdome

Laying out the greenhouse structure

Laying out the greenhouse structure

Firstly I laid out the struts in the pattern they would be constructed, six on the outside with two laid towards the centre at each joint. I had graded the struts so the least straight ones would form the base, reasonably thick hazel would form the sides of the icosahedron and the lightest, straightest hazel would form the roof struts.

For this basic ‘wild’ dome construction I used a very simple method of drilling holes and

copper pipe lining strut holes

copper pipe lining strut holes

connecting the struts with wire and rope. In order to stop the ends of my hazel from splitting, I lined each hole with a bit of used copper pipe.

I connected the holes on the base using fencing wire pushed through and bent over to hold the hazel secure but still allow movement. Then starting at one ‘corner’, I lifted the two sticks that would form a down-pointing equilateral triangle and used 2 foot lengths of high-tensile plastic rope to attach the top side of the triangle.

The greenhouse dome base

The greenhouse dome base

The reason I used rope rather than wire for these is I attached three ends together, untied to add a fourth and than later, once the sides were complete, untied again to add the roof strut to each vertex. I used reef knots to secure the vertices (right over left & under (thumb knot) then left over right and under).

This is where things got a little problematic. Once I had one side ‘up’ (always keeping an eye on the model) and moved onto the next, the opposite side of the ‘cylinder’ would collapse onto the ground and pull the structure down.

One problem with geodesics is that they do not become a self-supporting structure until they are complete. I might have wished for some assistance here and muttered quietly to myself about my partner Sarah always being out, but resolved the problem by staking the poles down with string, like with tent poles. This allowed me to hold up the structure while it was still flimsy due to lacking the top of the icosahedron.

I then tightened-up the joints on the base to restrict their movement. I laid out the roof struts, the hazel rods tapering towards the middle, and connected them at the centre, passing the rope through all five holes of the top vertex, leaving a bit of play.

The icosahedron greenhouse frame

The icosahedron greenhouse frame

I moved the top to the centre of the cylinder and set it up in a tipi shape. I untied each top vertex, re-threading the rope in some instances to allow for ‘settling’ of the wild wood, then attached the top struts. I supported the roof with a large stick for the last two struts. Six more reef knots and the basic structure was complete.

I included a central pole to add stability to the structure, slightly lifting the roof  which tightened the dome up. I took another photo of my ‘greenhouse’ and published it on Facebook where my family could take the micky out of me for building a greenhouse with no glass.

Posted in Uncategorized | Tagged , , , , , , | 2 Comments

Planning a DIY greenhouse

Buckminster Fuller with a dome

Buckminster Fuller with a dome

The invention of the geodesic dome is credited to Buckminster Fuller but is reported to have been invented 25 years earlier by Walter Bauerfeld for work on a planetarium projector at Carl Zeiss optics.  I ‘discovered’ them at art college through R. Buckminster Fuller and his amazing inventions.

Geodesic domes, to me, are quite beautiful. Lightweight and strong, they make very efficient use of materials which suits my pragmatist take on things. Geodesic domes are elegant and sophisticated structures. Deceptively simple to look at they hold a whole realm where art, craft, science, mathematics and nature peacefully co-exist. Fuller originated his mathematical principles of domes from observation of nature.

drinking straw dome

drinking straw dome

I had made some geodesic dome structures before, but never for a greenhouse: a 2 foot dome at art college made from drinking straws, a two metre dome out of garden sticks to grow over with sweet peas, some smaller models.

Every day my springer spaniel, Freya, needs a walk so often when we went I out I would take a saw and find and cut myself the longest length hazel rods of a useable diameter I could find, (in addition to providing numerous sticks for the dog).

Over the course of a couple of months of winter I built my collection of long, straight hazel sticks up to the 30 I needed for the icosahedron. I trimmed them down to an optimal length which came out at 196cm. Normally you would work out the size of the dome you wanted and calculate the strut length from this – but things don’t work quite the same with wild materials.

The reason for this seemingly arbitrary measurement is just so that I could choose the optimum length of stick available in the hedgerows. I just built the icosahedron with these and came out with a fair size greenhouse dome with a diameter of 315cm, an internal height on the inside edges of 165cm sloping up to 230cm in the middle. To add strength and stability (and to compensate for using ‘natural’ materials of irregular shape) I added a central pole to the structure.

For the more scientifically orientated of you, this intuitive dome making is hardly instructive. The icosahedron has 30 edges of the same length, in dome making these are often called ‘struts’. There is a relationship between the strut length and the radius of the icosahedron. The radius of the dome is slightly less than the strut length. With bigger domes, calculation involves a ‘constant’ called a chord factor and these can vary depending on what sort of dome you want to build. Some constructions, such as the 3 frequency icosahedron I built later, involve several chord factors in a single dome. The chord factor involved in an icosahedron is 0.95 . That is to say the strut length is 95% of the radius.

Firstly though, estimate the diameter of the dome you want to build, let’s say 300cm across, giving a radius of 150. To find the length of strut you need the formula is:

Chord factor x radius = length of strut

0.95 x 150 = 142.65

So you will need 30 lengths of 142.66cm to build a 3 metre dome.

It could be that to avoid the irregularities of ‘wild wood’ you might decide to purchase enough 2 x 1 planed timber to do the job and this is often available in ‘packets’ of 10 ready cut to 200cm lengths. In this case you will need 3 packets (get 4 in case of splits). Your ready-made lengths will give you a dome of these proportions:

Chord factor x radius = length of strut

951 x radius = 200 (200 divided by .951) = 210.3 x 2 = 420.6 diameter icosahedron.

If you estimate sawn 2×1 timber at 2011 prices, that is 65 pence a meter 40 x 65 = 2600 = £26 (which is about $40). So it would be easily feasible to construct this icosahedron greenhouse using planed or rough ‘2×1’ – but I didn’t want to spend any money.

The size of the dome is also going to vary a bit depending on how the struts connect to each other. There are several tried and tested methods for this in dome connection theory (deserves its own article – later). In an icosahedron each vertex (the singular of vertices) joins five struts – a very complicated joint for joining wood to wood, although it can be done. I decided to keep it simple for this one and drilled holes through the end of each piece of wood.

Posted in Uncategorized | Tagged , , , , , | Leave a comment

an icosahedron primer

What is an icosahedron?

An icosahedron is a 20 faced spherical shape recognised even by Ancient Greek mathematics – it is one of the Platonic Solids, which are: Tetrahedron, Cube, Octahedron, Dodecahedron and Icosahedron (see more about this).

An icosahedron is a regular polyhedron with 20 identical equilateral triangular faces, 30 edges and 12 vertices. It is a form found in nature, for example some viruses have icosahedral shells.

Ever since I learned about Buckminster Fuller at art college, who developed structures called ‘geodesics’ based on the icosahedron and other three dimensional structures, I have wanted to experiment more with making human-scale geodesics. So a first stage to ‘understand’ this shape is to build a basic model, this time using cardboard.

Firstly, draw out 20 equilateral triangles in the shape shown in the first picture:

Draw flaps around the edges of each triangle so that you can stick them together with a glue stick. Then cut out the shape and make some creases along the lines so that the icosahedron can find its shape:

Then start gluing the tab surfaces to the triangles to form a spere shape fom the cardboard. You may need to trim off some of the tabs as you go – you should end up with something like this:

I have drawn additional lines onto the shape to show how you can have different frequencies of geodesic dome, by subdividing the large equiliateral triangles. The smaller the triangles which go to make up the dome, the more it tends towards a sphere.

So this shape is the basic plan for my first greenhouse. As you can see from the above picture, you can ‘slice’ the isocahedron to make sub-shapes. In this case I will take the top five eights of the shape and create a frame using wild hazel from hedgerows, covered in polytunnel material.


Posted in Uncategorized | Tagged , , , | Leave a comment