Beginners Tunnel

I get where you are coming from and I'll take that advice on board and run with the standard green cover. Should I put door frames at both ends? I probably won't use the door at one end as access is limited. If the zip at the non usable door isn't used will it last?

What about the ground? The site where the tunnel is going has poor soil. I have a supply of good soil so I was intending to dig out two trenches where the raised beds are to go and fill these will compost and good soil. I have a riddle and will remove the stones from the soil.

 

That is the way to go in my opinion, your green cover has windows for ventilation but when and if you go for a proper polythene cover then you will be glad of ventilation at either end (both doors open create a through draft). Plus the doorways themselves become fixing points for new polythene.

I've been involved with or done half a dozen re-sheetings of tunnels now and for trenching in a little more than a spades width and depth was used, and the cover itself follows the frame to the ground and into the trench not impeded by anything. So bear that in mind if putting concrete footings in, this is why I used the stakes instead myself. This just future proofs you for when you go with real plastic.

No harm in digging ground over before hand, in fact I recommend it as it can be very hot work once the cover is on, I would not bother riddling it, just hand pick bigger stones as you dig, smaller stones aid drainage.

Steve...

 

Scrungee: What is the correct name for the metal straps you used to tie your tubing to your timber supports?

 

Wickes Multi Purpose Builders Fixing Band - 20mm x 10m | Wickes.co.uk

But I only used that on my first tunnel because the frame tubes were push fit and didn't have bolted connections. It was difficult to work with and required covering with anti-hotspot tape to prevent damaging the cover. But it can still be useful for joining bits of timber.

The 25mm dia. steel frame tunnels have bolted connections, enabling the supplied bolts to be swopped for longer ones, creating fixing points for all sorts of stuff. The supplied bolts also have nasty pimply projecting heads that will wear through covers, maybe even if covered with anti-hotspot tape.

Here's a few ways I used longer bolts to create fixing points:

Fixing timber battens along horizontal tubes enables screw eye points for fixing tops of bamboo cane supports.

'Hoop'/horizontal tube intersections are ideal for using longer bolts and L brackets to fix ends of internal raking supports, that can also be used to support demountable staging and high level shelving.



The upper horizontal batten below is fixed using Screwfix 25mm saddle clips, which enable a horizontal bearer to be fixed to support staging slats.



Extended bolts at the bottom of the 'hoops' enable both edging boards and L brackets cast into concrete pads to be fixed to the framework.

 

Cheers for that scrungee. My tunnel arrived this morning much earlier than I was expecting. I'll get the frame up over the next couple of evenings. I dug out a lot of subsoil on Saturday and dumped in a good layer of good soil. I'm going to put in raised beds so there will be more good soil/compost going in.



The bank on the right hand side will block some morning sun which isn't idea, but this is the only spot I have for the tunnel right now.

I'm like a child waiting for Christmas.

 

This is normal, at least it is for me, every tunnel move or new one, every sowing, planting and harvest. Just received my first seed order for next year.

Good to have a clear site to start with, it looks a mighty big space for the tunnel you have bought. One of the things you will get in a few months time is "It's not big enough".

Good luck and keep those photo's coming!

Steve...

 

You could have got a 3 x 6m tunnel in that space!

 

I have half the frame assembled and will get back to it when I have the kids to bed at 8. Enjoyable so far and fairly self explanatory.

I had cleared 4m long and its not long enough. I've had to clear a bit more. I have more room width wise but I need a walk way past the tunnel into the field.

 

I took this snap of the frame before the light faded.



I dug the trench at the rear and levelled the base after this photo was taken. If I drive the support posts on the inside of the frame there will be a 25mm gap between the post and the vertical bar of the frame because of the bottom frame. How do I overcome this?

 

That's one of the reasons I changed to bolted connections on those 25mm dia frames. Changing the bolt at low level will enabled the hoop/ground rail intersection to be bolted through any vertical timber just above ground level.

If you wish to fix the tops, use 25mm electrics saddleclips from Screwfix (cheapest I could find) to attach a 25mm thick horizontal timber at the required height. https://www.screwfix.com/p/deta-bzp...Aj-74jVo7FgaCVvS_j81zAf5yve8hIdRoCOoYQAvD_BwE N.B. For fixing a horizontal timber they need fixing so that downward pressure doesn't cause the saddle to be released from the backplate (if using) causing a nasty suprise if it's used as a staging bearer, or discard the plate and fix using washers to reduce the hole. Or simply plant timber packings on the rear of vertical stakes.

Temporarily putting the cover on and doing the zips up before anything is driven/ concreted into the ground will help avoid more nasty surprises after it's too late to relocate something. Do this before putting your anti-hotspot tape on as bolt heads may need accessing, and again after adding the tape as the cover will then be noticeably tighter. If a zip can't be done up all the way, don't worry as a small amount of the front panel can be allowed to ride back over the end hoop when fixing to door frame(s). Dont leave unfixed covers unnattended for even a minute if windy!

As soon as I've secured the 4 corners to the ground I remove the end ground rails as they get in the way when forming door openings.

 

Your photo shows you have the frame slightly skewed, the base rail has the four uprights connected on one side. The two corner uprights are outside the base rail, the two uprights in the middle are on the inside.

All of my uprights are fixed to the outside, so the base rail is inside, which then rested on the batten fixed to the bed, so overcoming the 25mm gap issue.

The tunnel frame is fixed to the raised bed, the raised bed is staked on the inside into the ground.

Grab one of my frame photo's and zoom in to see how it is.

Also, because I raised the frame off the ground I cut out the base rail at either end to allow for the doorways.

Steve...

 

Eagle eyes! Well spotted, I hadn't noticed that myself.

 

I have enough fence posts and have timber for the door frame, and don't really want to spend more cash and time getting timbers for battens. I'm going to take a similar approach to Scrungee. I'm just going to drive the 8 posts down and use the 25mm clips to fix the posts to the vertical frame. The door frame I will use concrete and fix to the frame. The cover will be trench filled.

So tonight weather permitting, I'll sort those mistakes Steve spotted and then try the cover on to make sure it goes on ok. If that works I'll start putting posts in which might not be easy with the stony sub soil.

 

I made a bit of progress last night. I corrected the mistakes Steve pointed out and then put the cover on which wasn't to hard to put on. I started to drive the posts in which was hard because the ground is so hard once you get through the layer of soil I've dropped.

The green cover really isn't pretty, my wife near had a stroke when she saw it! Our house is quite elevated and the tunnel is higher than the house, it can be seen for miles! And that's no exaggeration. I might go with the clear plastic cover. I found a company not far from me through gumtree this is the gist of their add:

-----------------------
Thickness 225 Micron 900 gauge
UV-10 product stabilized for min 10 seasons.
Heavy duty membrane meets the highest requirements of professional vegetable and flowers growers

Gardenvit Greenhouse Film is made of the highest quality raw materials in COEX-3 technology.
All films are ISO 9001 certified. The production technology guarantees high strength, long service life and high light transmission.
3-layer film manufactured using metallocene catalysts and the highest quality PE-LD
High light transmission up to 92-94%
Uniform light diffusion - perfect exposure
High durability: tear, puncture and stretch resistant
Flexible: with softening agent
Thermal effect A parameter defining the quantity of light transmitted through the film and its diffusion.Perfect light diffusion for uniform exposure.Light promotes growth and impoves fruit quality.
Tear , stretch and puncture resistant for greenhouses subject to strong winds and with lower quality frame.

APPLICATIONS:
construction of garden tunnels for a period of min 10 seasons
for crop protection in horticultures, agriculture and forestry
for crops requiring high light intensity, especially during low-temperature or cloudy spells, e.g. for roses or early vegetable cultivars
Its heat absorption ,at a level of over 80%, increases crop efficiency, accelerates plant vegetation and constitutes an effective protection against frost, allowing for considerable heat energy savings in heated tunnels
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What you guys think? I need to measure over the hoop tonight to find out what size of sheet I need. The tunnel is 4m long so I'd need 7m long to allow for a bit around the doors. An 8 x8 sheet is €89 EUR.

 

A proper polytunnel cover needs to be put on in warm weather, it heats up and stretches so you can get it tight, if that does not happen it will slacken off and become loose. If the wind can move it about as it blows, it starts to degrade the cover eventually leading to it failing.

As well as the cover, you will need anti hot spot tape to go over all hoops and supporting metalwork, as the metal heats up in summer, if it is in contact with the cover, it degrades it.

You will need timber battens to go around the door frames to fix the plastic firmly in place. You will also need help to fit the cover too, it can be done on your own but I would not advise this on your first one.

So there are extra costs involved over the cost of the cover, extra work and skill needed an extra pair of hands required and guaranteed warm sunny weather for a couple of days too,

Are you certain you cannot live with the green cover till next spring?

Steve...