Geodesic Dome Greenhouses

boatbuilder

What do you think of these dome greenhouses?
A few places making them in Ireland - anyone tried making one themselves?

Supercell

Never saw those before but looking at them online I must say I like them! The slope of the roof is far better than a traditional one so growing space is maximised. If they can stand up to the winds of the Irish climate then I would definitely consider one if it was the right price.
The only drawback that i can see is that getting shelving to fit it may be hard but i imagine there are probably companies making curved ones for these?

paddy147

Supercell wrote: »

Never saw those before but looking at them online I must say I like them! The slope of the roof is far better than a traditional one so growing space is maximised. If they can stand up to the winds of the Irish climate then I would definitely consider one if it was the right price.
The only drawback that i can see is that getting shelving to fit it may be hard but i imagine there are probably companies making curved ones for these?

They were on display and also on sale at Bloom 2012 and Bloom 2013.:)

dardevle

boatbuilder wrote: »

What do you think of these dome greenhouses?
A few places making them in Ireland - anyone tried making one themselves?

love the shape of them -very pleasing to look at but not sold on the practicalities of them.

I don't know what the cost would be if making your own but the cost of a purchased one is quite steep.....the biggest issue I have is in terms of heat absorption/ventilation, as the models that use polycarbonate sheeting get EXTREMELY hot in any kind of half decent weather and I have not seen any manufacturer address this issue with any success to date.

these guys are in Galway:
http://www.polytunnelsireland.ie/geodomes.html

Supercell

dardevle wrote: »

love the shape of them -very pleasing to look at but not sold on the practicalities of them.

I don't know what the cost would be if making your own but the cost of a purchased one is quite steep.....the biggest issue I have is in terms of heat absorption/ventilation, as the models that use polycarbonate sheeting get EXTREMELY hot in any kind of half decent weather and I have not seen any manufacturer address this issue with any success to date.

these guys are in Galway:
http://www.polytunnelsireland.ie/geodomes.html

Wow, those are pretty expensive. Nice though if you can afford it.

paddy147

Some pics of them I took at Bloom 2012.:)

redser7

They look funky but what's the advantage? Where's the vents?

dardevle

redser7 wrote: »

They look funky but what's the advantage? Where's the vents?

I suppose internal space is the advantage.....but how you lay it out is another matter.

very little in the way of ventilation - just the door and on some models the addition of a couple of windows at more expense.

could be made fit for purpose (I am currently working on adapting one for propagating/growing) but this will add to the already high cost.:o

tommy2bad

I wonder if something like this;
bike-dome.jpg
And some polythene would work?

Pic from http://kiacblog.wordpress.com/2011/08/19/arts-fest-weekend-art-fair-workshops-demonstrations/

boatbuilder

They look fairly easy to make - this fella sells plans.

http://www.geo-dome.co.uk/domeshop/artsearch.asp?show=all

Apparently you make it out of roughly 2x1 treated timber.
Its just lots of triangles screwed together.

I suppose the advantage is that a dome is a very strong structure and can withstand winds that could damage a normal polytunnel - and they look cooler than a polytunnel. For vents you can have some of the triangles opening...

I think I might give it a try - hard to choose a design and size though!

Maybe a 4 metre version of this? It's a pentakis dodecahedron dome which is one of the easiest to make because all the triangles are identical.
The fella reckons you could make one and cover it with horticultural polythene for £100 sterling - can't be bad!

dardevle

.


interesting project - I would love to be able to follow your progress if you do go ahead with it.

hard to see how it could be done for £100 when you factor in time and materials?




.

paddy147

A 16 foot length of PT 2 x 1 is around 2 75 cents euro in any good builders providers.

http://www.goodwins.ie/p-742-treated-rough-sawn-timber-50mm-x-22mm-48m.aspx


http://www.goodwins.ie/c-48-construction-treated-timber.aspx




You will get the horticultural polythene in the likes of a good agri store/nursery or else NAD.

www.nad.ie

Kerry_2008

There is a great youtube videos about their construction
http://m.youtube.com/watch?v=ZBV1RE3uKvo&desktop_uri=%2Fwatch%3Fv%3DZBV1RE3uKvo
http://m.youtube.com/watch?feature=related&v=ZBV1RE3uKvo


Would be really interested to see how you get on, will you update us as you go along?

boatbuilder

Yep I'll do that, hopefully will get something done by Christmas time!

KAGY

boatbuilder wrote: »

Yep I'll do that, hopefully will get something done by Christmas time!

I think I'll keep an eye on this too. I was thinking of building a poly tunnel using the black 2" water pipe, braced with treated 2x1, but this looks more interesting. I'd just be concerned with rubbing as there's a lot more contact points - unless each triangle is covered separately?

boatbuilder

Each one is covered seperately so if it gets holed hopefully it would just be a matter of unscrewing that triangle to recover it.

KAGY

Just looking into this some more, and came across this site:
http://katiecorrell.com/2012/11/09/geodesic-dome/
Interesting how they create the joints -

I'm going to mess around with SolidWorks just to keep my skills fresh. I may just look at 2V domes as there is no cut triangles in the hemisphere. I'll post up if/when I'm done.

boatbuilder

Yeah some designs use hubs at the joints, but I can see some disadvantages to that....
You'd have to spend time making the hubs for a start, plus you would have to cover the entire thing with one sheet of polythene, which I understand would be pretty much impossible to get tight on a dome in one go.

Funny you mentionned Solidworks - never used Solidworks myself but I had a go at drawing a 3d dodecahedron in autocad at the weekend - just about managed it, but got totally stuck after that. Next step would be to "pull out" a pyramid on each pentagonal face to make a pentakis.
Here's the dwg file if its any good to you -
http://wikisend.com/download/254064/dodecahedron.dwg

I reckon its well worth the money paying the geodomes.co.uk fella for the plans!

KAGY

Okay, hope that this might be of help to you. A 2V dome is basically made up of pentagons with only two lengths as per the attached drawing.
For a radius of 1000m Outside of pentagon = 682.88mm, inside = 609.95mm. I did it that way so it's easily scaled.
Next step, I might try to use those figures to create weldments of the repeating pentagon (or possibly the equal triangle) and add them together in an assembly. I will also add a relationship between the two measurements so we can change the dimension of one and have it update.
But don't hold your breath, I've new class plans to prepare ... which I should be doing now ...

For those of you with solidworks who want to know how I got these figures

• Create a thin feature by rotating an arc, just to get the sphere for reference
• create a 3D sketch and draw the 5 spokes, making the hub coincident with the arc you drew the thin feature with
• add the relation "on surface" to each of the ends and an equal length relation to each of the spokes
• join the ends and add an "equal length" relation to these
• Draw the two triangles that I have show reaching down to the base of the hemisphere and add the appropriate "equal length" relationships and make sure the base vertices are coincident with the base of the hemisphere.

There should only be one sol'n to this as shown!
Alternatively, check this pdf for the maths :eek: http://mathcircle.berkeley.edu/BMC6/ps0405/geodesic.pdf

boatbuilder

Yikes that Maths is way over my head!

KAGY

Back of envelope calculation for timber
Least waste diameter assuming 4.8m 2x1s is 5.2m
If it was constructed by making up each triangle you'd need 60 lengths of 1.42 and 70 of 1.41. ( that doubles up the base struts so you could reduce the 70 to 60)
This needs about 44 lengths at about 1.80ea

KAGY

...and I can't find the edit button. (Is there a time limit on it? 'cos it's here for this post!)

I made an error setting up the dimensions above, which I only found when trying to make the assembly (in CAD). (assumed incorrectly that two struts were the same length)

here are the correct figures:
Strut A - 546.53 Strut B - 618.03 (again for 1m radius)
I'll have to check the figures in my last post too.

boatbuilder

I've decided to go ahead and order the plans for the 4 metre version. Looking forward to getting started.

KAGY

boatbuilder wrote: »

I've decided to go ahead and order the plans for the 4 metre version. Looking forward to getting started.

Looking forward to seeing your progress. I'll leave this thread for your use now. I'm going to continue my cad exercise and will start a new thread over on diy when I get the model finished.
Happy building :-)

redser7

Put a duplicate thread up here to KAGY, plenty will be interested

boatbuilder

Just got the plans - 11 pages of drawings and instructions. I think he sent me the 3 metre plan by mistake but I might just make the 3 metre one anyway.
It would take about 18 lengths of 2x2 treated timber (cut down the middle at the required angle to make ~2x1)

At €3.50 per 4.8 metre length and allowing 2 lengths spare to make a door and an opening window, that would be 3.50x20= €70

You'd also need a couple of lengths of 3x2 for the base and door frame and a sheet of half inch plywood for around the door opening.

Then some horticultural polythene, staples, screws.
Looks very do-able.

OldRio

Good luck with the project lads.
Keep us informed.
I'm busy at the moment but this sounds a great project for the coming months.

redser7

The polythene can work out pricey. Chap on adverts selling some, might save you a few bob ...
http://www.adverts.ie/other-home-garden/polythene-polytunel-greenhouse-polythene/2872377

boatbuilder

I reckon it would take 9 linear metres of 6m wide polythene to cover it all including the door. €70 to €80 should do it.

KAGY

boatbuilder wrote: »

It would take about 18 lengths of 2x2 treated timber (cut down the middle at the required angle to make ~2x1)
...

You'd also need a couple of lengths of 3x2 for the base and door frame and a sheet of half inch plywood for around the door

Do you have access to a table saw? It'd pretty difficult to get a consistent cut length otherwise. I'm trying to design it with the two pieces flat to each other.

boatbuilder

KAGY wrote: »

Do you have access to a table saw? It'd pretty difficult to get a consistent cut length otherwise. I'm trying to design it with the two pieces flat to each other.

Don't have a table saw but I have a band saw with a one inch blade so hopefully it'll be up to the job. If the pieces were flat to each other would you have to have compound cuts of some sort at the ends of the struts?

KAGY

boatbuilder wrote: »

Don't have a table saw but I have a band saw with a one inch blade so hopefully it'll be up to the job. If the pieces were flat to each other would you have to have compound cuts of some sort at the ends of the struts?

Yep. But I think that there's enough to justify setting up a jig. There's also the problem that the two sizes are at different angles so the mitre at that join is very odd. Thinking of butting that one and planing the sticking up bit (technical term). Hopefully will get back at the cad this weekend

redser7

Thought you guys would like this ...
http://www.youtube.com/watch?v=9rn6YtCC670

10 videos I think and he goes into great detail, builds a rocket stove to heat it too.

CorsendonkX

Looks really like fancy garden furniture rather than practical growing house. No vents, only the door. How do you support tall crops in the structure? Also you can only grow small crops on the sides of the dome due to limited head space.

tommy2bad

CorsendonkX wrote: »

Looks really like fancy garden furniture rather than practical growing house. No vents, only the door. How do you support tall crops in the structure? Also you can only grow small crops on the sides of the dome due to limited head space.

Yep true enough but nothing wrong with fancy garden furniture. I imagine ventalation would be a problem unless you work some vents/ windows into the structure.
As to space apart from tomatoes you don't need that much head room and a few bean poles would support any toms you were growing, it works outdoors for me.

Supercell

Watching this thread with great interest. Boatbuilder please please make sure to post pics during your progress! Once made, have you given thought to the inside?, will you grow in the ground or are you planning on making custom shelving (or a combination of both) ?

/Off topic - Redser7 how goes your own greenhouse project, is it up yet?

redser7

Supercell wrote: »

Watching this thread with great interest. Boatbuilder please please make sure to post pics during your progress! Once made, have you given thought to the inside?, will you grow in the ground or are you planning on making custom shelving (or a combination of both) ?

/Off topic - Redser7 how goes your own greenhouse project, is it up yet?

Oh yeah meant to post pics. All done. Been building the staging so nearly there. It's turned out nice and sturdy and its such a pleasure to be able to just walk out the back to do some undercover gardening!

redser7

Gimme straight lines any day

boatbuilder

For ventilation you make some of the triangles so that they can hinge open.
Yes I reckon a normal greenhouse with a similar square footage would be more practical, but I think a dome is more quirky and interesting.
I haven't thought of the inside layout really at all yet - but imagine will make some kid of narrow circular shelving around the edge and a central area to sit in! Its not going to be for serious growing - just a nice space to be in with maybe flowers etc growing around in a circle.

Having second thoughts about using polythene to cover it, as it may get vandalised too easily in the place it is going to be in.
Anyone know a cheap source of polycarbonate sheeting and what kind of tape you could use to seal the joints?

I ordered the wood today, so no turning back now.

redser7

Even a cheap source of poly carbonate will work out extremely expensive.
If you do go with poly c. People recommend you silicone the ends. Otherwise moisture will get in the channels and eventually algae will grow inside. I've done that with mine. I really would be inclined to go with the horticultural plastic, 800 gauge plus is really tough.
How about a standard fruit tree in the middle. Something that would appreciate the shelter. Peach maybe? With seating around it ...

https://www.google.com/search?site=imghp&tbm=isch&source=hp&biw=981&bih=450&q=seating+around+tree&oq=seating+around&gs_l=img.1.1.0l4j0i5l2j0i24l4.2264.6411.0.8198.14.12.0.2.2.0.109.1066.9j3.12.0....0...1ac.1.27.img..0.14.1086.KJ6MuR3vv3s

But you have to have ventilation. Otherwise everything will die. Either from extreme heat or moulds and mildew etc. even two doors facing each other would help.

boatbuilder

Yeah I just saw the price of twinwall polycarbonate and quickly changed my mind back to polythene!

boatbuilder

Got a price from NAD - 180 micron thermic polythene 5 year - €92 incl postage

redser7

That's where I got mine. What width and length did you get?

boatbuilder

9.2 metres wide, 6 metres long.

The fella seems like a decent bloke - Colm Matthews... he phoned me and spent lots of time explaining the pros and cons of polythene etc.

boatbuilder

Well, started on the 3 metre dome last week - I used 2x2 treated timber and cut it on the bandsaw at the required angle.... a new blade on the saw would have been a help as it tended to wander a bit, but I'm hoping it will be accurate enough for it. I'm not a big fan of table saws for safety reasons so use a bandsaw where possible.



So far, I've made five isoceles triangles and fitted them together to form a pentagon - seems to fit together ok...I'm using one 4x70 screw in each corner of each triangle.

boatbuilder

Struts are all made from the same cross section material... I've colour coded them because one end of each type has a particular angle cut at the end of it.





Here is the jig for making the triangles....




And here are five triangles joined together...



Next step is to get the students going on putting the rest of the triangles together, sand the edges so it doesn't tear the polythene and then paint with Ronseal Woodland colours "Willow"

redser7

This is great. What polythene will you be buying? Make sure it wont degrade on contact with the Ronseal.

boatbuilder

180 micron polythene from NAD.
Hopefully if the ronseal is allowed to dry properly there should be no problems!

This polythene is thermic and anti-fog and is guaranteed UVI stable for 5 years. You enquired about heavier polythene. It used be that the heavier the polythene the stronger it was but that is not necessarily the case nowadays. The technology used in modern methods of polythene manufacture can produce lighter, more flexible films which have higher tensile strengths and puncture resistance than the older types of polythene cover.

redser7

Got mine there too. I remember coming across a piece discussing polythene failure. Not getting it drum tight was number one, but contact with chemicals and preservatives was a factor too that led to premature degrading. So do some research on that. If it's pressure treated maybe it's ok without the Ronseal?
It will get very humid and there will be a lot of condensation running down the plastic and pooling around the timber so the ronseal might run??

redser7

Found this advise ...

Leaching out of chemicals. We suggest that you find a water based wood preserver low in chlorine.

boatbuilder

I rang the guy who did up the plans and he said it should be ok so long as I choose a light colour. As far as I know the Ronseal woodland colours stuff is waterbased - it says you can clean brushes with water and detergent...