In the vegetable garden at Fronrhydd we have the frame of a decent sized polytunnel, which lost it's 'poly' in the last winter storm. On inspection, we concluded just about all the wooden base rails (the bits the poly attaches to) were rotten or failing, though the frame itself is in pristine condition.
We spoke to the tunnel suppliers some time ago, and worked out with them that we could replace the main side rails with aluminium versions that come with a simple system for attaching the poly sheets, and would last a long long time. We chose to go this route for a refurbishment of the tunnel, and ordered these bits, plus a new poly covering.
The first 'adventure' was that to fit the new base rails. We had to detach the end-hoops completely so they could be lifted off their posts, and the fixing brackets added. That wasn't too bad once we'd identified all the bolts to undo, but it did mean the frame was never going to return to exactly the same position as it was before, so here came our first bits of improvisation. Ably assisted by my daughter Bex, visiting for the weekend (well, we all have to earn our keep these days!), we got one end done on Sunday morning, but were distracted by visitors in the afternoon. The opposite end was sorted on Monday.
Attaching the new base rails was next. The first side was fairly painless and everything seemed to line up and fix together properly... well after a visit to the hardware people as the polytunnel people had forgotten to send us some of the fixing bolts we needed.
The opposite side proved a little more tricky, but nothing a sledge hammer couldn't fix to get the bolts through the holes! But then we got to the front corner bracket which was never going to line up. A quick check revealed a rogue collar below the bracket, which needed to be above it. Sounds simple, until you realise to fix this you have to detach the whole end loop once again, in order to lift it out of the way and swap the two parts - Grrr! Anyway, swapping them fixed this issue, and once the end hoop was reattached, the second side rail fitted nicely.
Next came the fun bit - getting the sheet of poly (yes, it's one single sheet!) up and over a frame 25ft long, 13ft wide, and over 7ft tall. Plus spare poly is provided to allow for the twists and turns you have to make to fit the sheet, and it has a 'right side' that needs to face outwards once installed.
We unrolled the sheet as much as we dared, pondered a while which way was 'Up' for the sheet, pondered even longer on whether to lift it over width ways, or length ways. In the end we decided on the 'suck it and see' approach, and just went for it.
More by luck than judgement, it looks like we got it right first time, and also got it into position without any noticeable damage to the sheet. I would like to say though that we were blessed with a few days of beautiful weather (dry and virtually wind free) which was a blessing I'm sure. I guess if the two of us had attempted this in anything worse than 'nearly calm' weather, we'd be flying over Pembrokeshire right now, hanging on to a very large polythene kite.
So far so good, and I guess to this point we were managing more 'chic' than 'shabby'.
Our 'make it up as we go along' approach continued with attaching one side, and then the other - pulling the poly as tight as we could in the process, and then attaching to the front and rear frame, again as tight as possible. If I had done my research better, I'd have know one is supposed to do these two steps in the opposite order, but it seems to have worked well enough - slightly shabby, less chic!
Then you have to wrap the poly in over the curved sides of the frame, to reach and attach to the door frames as tight as possible, folding the poly on the faces as much as necessary to get round the curved frame and maintain as much tension as possible. The front ended up as the 'shabbiest' bit of the job (unfortunately), but the result is a closed structure with poly, more or less, in the right places!