Tunnel Vision

home made polytunnel
The finished polytunnel

As you may have seen from our previous posts the construction of the polytunnel has taken a while (due to some terribly wet weather), so when we finally had a dry spell it was all hands on deck! Many thanks to Theo’s parents Hugh and Alison, and to Rodney who we couldn’t have done it without.

Getting the field ready…
We needed to turn a scrubby patch of grass into a fine tilled veg bed so our first step was to plough. Rodney is the proud owner of a beautifully restored old Massey Ferguson tractor which he put to good use churning up the field.

Once ploughed we had to wait a bit for the weather again, before it was dry enough to power harrow, breaking up the soil and levelling out the land.

harrowed field

Now that we had a beautiful field of mud, it was time to start putting a polytunnel on it.

Building the skeleton…
Using a very heavy post-whacker we got the 5ft scaffold pole halfway into the ground. These will be our foundations so we wanted them to be sturdy. To get the tunnel rectangular we measured the diagonals to make sure they matched and checked they were what they should be with a bit of trigonometry. And there was me thinking I’d never use it!


We then used 63mm MDPE pipe for our hoops, which fitted on tightly over the ground anchors (scaffold) and were secured in place with a large nail all the way through and hammered down on one side. This job can be made much quicker and easier by using the right tool so make sure you use HSS drill bits when drilling through metal! We snapped a cheap drill bit before we switched to one made of sturdier stuff.

We also duct taped around the join so it was smooth, with no jagged bits for the polythene to catch on when we pulled it tight.

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nail through pipe
Nails in and knocked flat, duct tape smoothing the join.

Once the hoops were on, we needed a way keep them secure so they didn’t bend. We fixed 1” battens along each side and along the top with screws going directly into the hoop. To make this easier we drilled pilot holes into the wood at measured out intervals and drilled the screws in part way. This meant when we were holding up the battens it was just a quick ‘whzzzzz’ at each hoop, rather than an endurance test for my shoulders as I held the wood while Theo changed drill bits from pilot hole to screwing in. (Again, we did a couple of battens worth of holding up and drilling before we cottoned on to this!!!)

hedge side battens
 4m battens x3 across each side keep it in line.

Next we used 2″x 2″ timber to build frames at either end and support pillars under each hoop. These will ensure our structure keeps its shape when the polythene is pulled tight and prevent any sagging. The supports will double up as a frame for our tomatoes to grow up – no space wasted!

frame middle and ends
Hoops up with battens, end frames and support struts down the middle

Now our general structure was complete, we needed to get ready to secure the cover. We dug trenches down each edge to bury the polythene ends with enough weight to hold the polythene taut. Ours were approx 1ft wide and 1ft deep, a general guide for smaller tunnels is a spades width and depth, but Hugh had fun with a digger instead….

Before we put the cover on, we used anti hotspot tape over the entire length of our hoops. A bit ‘belt and braces’ but its pretty cheap and as our polytunnel is home made we thought it was better to be safe than sorry. It’s basically a sticky back foam strip that gives the polythene a soft point of contact and stops there being any difference in temperature/ texture when the frame goes from plastic to metal. So hopefully no condensation or melting plastic and more importantly no rips!

polytunnel hoops covered with anti hotspot tape
Each hoop covered in tape

Putting the cover on…
Finally after all our preparations, it was time for the polythene cover. Luckily the weather was on our side for a change and we got a warm day with wind that wasn’t too strong. With 4 sets of hands and a couple of ladders we managed to pull the sheet of plastic over the hoops and line it up in place.

loose cover on
Draped polythene, with a bit spare

We then backfilled the trenches down one side then the other, pulling the plastic tight as we went.

Polytunnel with 2 sides taut
Both sides trenches filled in, ends loose

This took a bit longer than we anticipated and by the time we had pulled tight and battened down one end of the tunnel it was getting dark!
With the help of our car headlights we managed to get both ends secured, battened and as taut as possible.

Time for bed!

Now its up….
In the few days since we got the major work done we have carried on with a few bits and bobs but it still needs some final touches.
We have made one door and hung it – the bottom is polythene and the top is a fine mesh, which will aid airflow through the tunnel but stop any hungry caterpillars getting in. We also have some of this mesh above each doorway as ventilation.

polytunnel door
The first door and airflow vent completed

We have screwed some horizontal bars to the middle support struts at the top and bottom which give it extra rigidity and make it not only a good climbing frame for our vines but a perfect crop bar for our hanging baskets.

polytunnel support
Our middle support bars, ready for crops to grow up and down!

We still need to finish the door for the other end and finish burying the edges of the polythene but for now we are concentrating on the inside! The ends are a bit looser than we would like them to be so we plan to get some more battens and fix the polythene to the diagonal bars in our end frames (visible in above pic), which should hopefully stop the rattle of the wind being quite so ferocious.

We have started digging the soil over now and soon we will be moving seedlings out of our tiny greenhouse and into our much roomier 6mx10m polytunnel!

polytunnel with tree and geese
Some geese having a gander at our finished tunnel…

Check back soon to read our next post all about getting the soil ready and moving in our plants….

Cheers!
Theo and Pippa

PS : While we were doing our research into how to build our tunnel we came across this great website. So if you are looking for additional info, check that out.
Below is a list of our materials and where we got them…..

What we used:
6 x 5′ Scaffold poles
63mm Water Pipe (50m coil)
2″x2″ timber
1″x2″ batons
Polythene cover
Anti hotspot tape
Nails
Screws
Duct Tape
TLC

Where we got it from:
Scaffold poles – Cut from old farm gates
Water pipe – Builder’s merchant.
Timber and Battens – Builders merchant was the best price we could find for the longer lengths we needed, but we’d always recommend for you to check with a local supplier, especially if undertaking a smaller build.
Polythene – Northern Polytunnels, priced per metre with many different specs depending on your geographic climate/ weather.
Nails, Screws, Duct tape – our local hardware store.

Thanks for reading all about our tunnel. If you have any questions for your own build, comment below and we will get back to you as soon as we can. 🙂

 

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4 thoughts on “Tunnel Vision

  1. Are you sure you didn’t use twelve 5′ scaffolding poles??
    Very impreessive structure. Professional finish.. and hopefully you saved a shedload by DIY-ing.
    Well done.

    Liked by 1 person

    1. Yes, twelve poles! Oops.. 😯

      Thanks for the kind words, it cost under half the amount of a new poly with similar dimensions.

      Like

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