DIY Autonomous Lean-to Polytunnel

[Jay-ell]

https://youtu.be/vt0Y39eMvpI

Right - it's curtains for you.

Would you prefer the velvet ones or the chinz?

[Jay-ell]

OK, to recap. The perimeter fence has metal fence posts. Across three of these fence post you have two 38mm poles cable tied. These poles are joined to a fence panel (with the side poles removed) on the top pole. The top and bottom poles of the fence panel are connected by scaffold poles shorter than the fence panel height causing the panel to make the arch roof.

This roof is then connected to the front panel using steel cable in such a way that it can swing like a hinge(?). the front is at an angle and pushed against posts at the bottom to stop it moving, but isn't fixed to the ground. Everything is then covered by plastic sheeting.

What is the front made from - it looks like scaffolding poles.

[no_akira]

The front panel is made from roofers blue coated mold resistant baton screwed together and further strengthened with cross batons. The scaffold cladding sheet is stretched over the batons using Scaffold ties pushed through the holes in tape on tarp.

Pack of 50 100 Up to 1000 Elastic Scaffold Toggle Ties Sheeting Bungee Ties | eBay

https://www.allplas.co.uk/acatalog/S...s_Netting.html

[Jay-ell]

You say it's easy to put up, how heavy is the whole thing? Is there a risk of the wind whipping it away in a heavy gust?

[no_akira]

I was able to erect this structure by myself...

The roof panel section is made from the thicker tubed (38mm) heras panel for added robustness. To overcome the failing of the MK1 version 2016.
A 21mm car wheel brace fits the heras clamps (useful tip).

The front panel is like a large kite, light, under 10kg id say. The elastic barbed cords give the front panel tension like a drum skin.

The cladding sheet is thick, remember its meant to last the length of a building site which could be up to 2 years often in highly exposed positions.

The open sides lets the wind pass around it, so shouldn't get too hot in high summer. Just a couple of degees temp diff. But mainly its about wind protection.

Note: On the leading edges of the roof sheet I have stapled 1.2m light pallet planks (sheet wrapped both sides of plank) and drilled 12mm holes so that the bungee strap have got something strong to pull on. Without these planks the wind might rip the plastic away

[Jay-ell]

Based on what you've said about the construction the problem I see with this is that it is like a large kite and is only secured by the cable ties to the fence.

As you say the weight of the front panel is 10kg, tall enough to work in and it's 3m long a good wind could catch it and lift it and turn it into a flaying flapping thing made out of wood and steel.

I think you need to revisit how it is secured to the ground and definitely look at securing the front panel so that it can't be lifted by the wind.

[Nicos]

^^^^^^agree....a kite does come to mind to me too...but I have to say, it does look great!

[no_akira]

Remember this is MK2 version...

MK1 lasted 12 months and used the thinner heras panels & thinner gauge plastic. It never got caught by wind.

The front panel rests on x2 of my "pallet dividers" that water the tomato s, it would be easy enough to drill a couple of holes & metal wire tie to further secure the panel.

cheers Nico... ������

[Cadalot]

Where's Cadalot when you need him

Working late on getting the Hall Stairs and Landing completed before the carpet layers arrived today

Have read the transcript of the Spanish Inquisition, (yes we do like to ask lots of questions and understand what we are looking at), I would say it need adequate anchorage at the ground and all connections

The only change I would have made is not have the braces in the front panel in the same direction \ \ I would have had them \ / so that one was in compression and the other in tension which ever way the wind blows through the structure and it provides a much stiffer structure against lateral loads.

The curved roof is inspired and solves the holding water and bowing problem of the Mk I version. That basically is what design is all about, before we started to analyse and calculate, it was build it, watch it fail, make it better, see if fails somewhere else make that better.

Building techniques evolved, however it appears that the current bunch of Architects have forgotten what a ceiling tie purpose is other than support the ceiling and they want to design sloping roofs without them.

[Jay-ell]

Well you got a lot of good bits for your £30 - you obviously know where to look.

As Caders said, we like to understand what it is so we can give feedback. Never thought about the arrangement of the bracing.

[Cadalot]

Jay-ell - Bracing is something to think about when making long inverted V Runner bean frame supports out of bamboo.

[Jay-ell]

I know that, looking at the photos I didn't pick up on the bracing in the same direction.

[veggiechicken]

Thanks no_akira for answering my questions - I have a better understanding of the construction now. It wouldn't work for me as I don't have any high fences and I'd have to buy Heras panels. If I did summat similar it would be with wire mesh, arched at the top and panels at the side.

For those of you who have implied that this has been like the Spanish Inquisition, don't you have an enquiring mind of your own? Surely its better to ask questions and show interest in a design than give a Like and move on.
A forum is a place to discuss, ask questions and receive answers from the wealth of knowledge that our members possess and happily share. So don't knock it when people need to know more.

As you were...............

[Cadalot]

VC am I sensing a sense of humour failure?, as a Python fan I loved the link to the video on the thread...

[JARRING CHORD]
[The door flies open and Cardinal Ximinez of Spain [Palin] enters, flanked by two junior cardinals. Cardinal Biggles [Jones] has goggles pushed over his forehead. Cardinal Fang [Gilliam] is just Cardinal Fang]

Ximinez: NOBODY expects the Spanish Inquisition! Our chief weapon is surprise...surprise and fear...fear and surprise.... Our two weapons are fear and surprise...and ruthless efficiency.... Our three weapons are fear, surprise, and ruthless efficiency...and an almost fanatical devotion to the Pope.... Our four...no... Amongst our weapons.... Amongst our weaponry...are such elements as fear, surprise.... I'll come in again

And yes normally I would have asked a load more questions but my "little nest of vipers" has been keeping me busy with decorating.

[Nicos]

Sorry, but I think perhaps we all need a break from this thread for now.
I'm going to close it, but... no_akira....let us know if/when you'd like it opening again please.

Well done so far, and I hope other Grapes' advice has been of some help?
*Will there be a Mark III?......