Construction of the Polytunnel

Before we’d even purchased the ‘orchard’ behind the cottage, it had always been our plan to site a polytunnel if we ever did have an opportunity to buy or rent the land. So, in September 2021, just a few months after buying the acre or so of land, we put an order in to Polytunnels Direct for an 18′ wide x 30 ‘ long tunnel. The orchard by now had been tamed slightly and some good friends with a mini digger kindly took off the top of the proposed location spot.

Because we have electric cables running over the field, we also called out our local electricity supplier, Western Power, to advise on the location and safety aspects. These guys were (and indeed always are) really helpful and they advised us that there is an underground earth cable buried somewhere near the polytunnel location. To date, we’ve still not found it.

To begin the construction, we firstly dug holes, around a metre or so deep for each of the dozen or so ‘foundation tubes’ (the ground level tubes that the arch tubes slot into). As it can get extremely windy down in the orchard, we strengthened the tubes by drilling lengths of rebar through them and then weighed the tubes with rocks before back filling with the soil. The tubes themselves were pretty easy to erect and we paid a little extra for ‘storm bars’ which brace the top of the polytunnel from strong winds which can rock the structure from side to side. We also drilled and inserted loose screws through the foundation tubes where they met the main hooped bars so minimise the likelihood of the hoops ever detaching from their anchor points.

Before we then added the plastic, we had to build the ends up with locally sourced timber and we made two outwards opening doors at each end, which not only allowed easier access with wheel barrows, but also allowed doors to be opened both ends on sunny days to allow better airflow. We didn’t know at the time when building the tunnel, but temperatures could approach 50 degrees on warm sunny summer days inside.

It also made sense before getting to the plastic stage, to create the raised beds inside the tunnel using railways sleepers sourced from a contact that Russell’s business provided services for (Bradfords) and we also added weed membrane between these sleepers which in turn would then get covered in woodchip to act as paths (wood chip supplied by local tree surgeon). The beds were turned firstly by hand, and then several tonnes of locally sourced compost were barrowed in along with around 4t of fresh farmyard manure, which was allowed to rot down over that winter. We also continually added chicken bedding and manure and seaweed. It’s fair to say the tunnel stank a bit for a while.

The first year of owning a polytunnel see’s owners watching weather forecasts like a hawk, and our first job was to find a break in the weather for the wind to drop to less than 10 miles per hour. Anything more than that and the 1500 square feet of plastic would just act like a kite. Finally, one weekend, the forecast was for winds of 2-3 miles per hour, for a few hours – almost unheard of in Delabole!

With the assistance of some good friends and neighbours, we took to the task one Saturday morning of fitting the plastic sheet. We had already dug, to a depth of about 1 metre all round, a trench to bury the plastic in. But, because the steel bars would undoubtedly also get very hot in summer, we also added a special type of polytunnel heat tape to the outside of the bars for where they came into contact with the plastic. Then, with the aid of our friends, we pulled the plastic tight over, and backfilled the trenches, adding salvaged breeze blocks that we discovered along the edge of the field, for extra weight on each corner.

The door ends were trickier but didn’t require our friends to remain on site, so we patiently made 2 x pairs of timber doors each end, each with a cross bar, plus a timber door step, and painted the timbers grey to sit more naturally and neatly in the landscape. With some adjustments, we eventually got the doors shutting more or less as they should.

Whilst we thought this was it for the construction, we soon discovered less than 2 months later that nature wanted it’s say in the tunnel too. Read our ‘Living with the Polytunnel‘ article for this story.