Poly-tunnels ??

[Bayleaf]

There are so many factors to take into account, Bayleaf Mainly, which direction the wind comes from (it just whizzes over the curve if it hits the side) and how taut the cover is. Would stretchy cord perhaps 'relax' with time and exposure to the elements? Perhaps not if it's UV treated like the covers

Indeed - lots of factors, and depending which way the wind is blowing as to whether it's going to try and convert the tunnel to a kite! I'm thinking about using the stretchy cord as an "in the event of" rather than a permanent fixture. As you so rightly say, it will relax and erode after time. We watch the weather closely, as our work depends on it, and in the event of storms, try to do an outdoor walk-about of battening down the hatches, which would include giving the tunnel some extra support. Just something else to think about ....

[Hotrodder]

In the Charente, a new poly with the flaps weighted down with heavy stones lasted less than a week.
In Brittany, a similar poly tunnel weighted down in similar fashion until the end of summer. Then I took the cover off and stored it away for safe keeping. Gale picked up the tubular frame and destroyed it.
Tunnel number three I weighted the flaps down with 5 foot long solid concrete fence posts. Works fine.
Two years ago I treated myself to an all steel shed 3 x 6 metres to store the tractor and mowers. Screwed down to heavy timber beams and the beams had steel spikes hammered through them into the ground. A gale blew the doors inward, got inside and lifted the whole structure 2 metres+ into the air and dropped it down, destroying every panel in the process. Wife was at the other end of the garden and saw it happen.
Two other sheds of similar size survived undamaged. The only difference was they both had sliding doors and were turned 90 degrees.

[L Austin France]

This is our tunnel, looking a bit worse for wear after a growing season followed by hay storage. The roof section is surported by solid plastic cord a la Quicksilver tunnel & the gables are braced. The metal arcs are insulated, where they touch the bache, with old bits of bache to help avoid friction & heat tranfer. All sides are well buried.
So far so good as after 8-10 years with this bache all seems fine.

IMG_20220123_153932_compress41.jpg

[Hotrodder]

I'd be tempted to live in that. It looks cozy and warm.

[Quiksilver]

Must be nice to have time to sit down I wish! In fact, must admit to having a plastic chair in the chicken hut...I go in there for a bit of intelligent conversation

[Polarengineer]

With a chair?

[Blaze]

@Hotrodder We're a bit further east than you are but nonetheless subject to very strong winds from the south and west, but also from the north-east. We have to think carefully about everything we do in the garden with regard to wind direction. Most of the garden is reasonably protected from the north but we're thinking of planting 3 or 4 poplars as a windbreak. The 2m high wall isn't high enough. We still can't decide where to put the greenhouse. Logically the lee of the house would be the safest, but would be too close to the house ..... too far out and the risk of breakage could be serious .

[Quiksilver]

With a chair?

Smarta*se With the hens, of course.

[Char]

I'm quite used to running round the garden collecting up the plastic panels that have been blown off of the greenhouse, (I've stopped that now by screwing them onto wooden battens).
We also had an episode where our large tin shed decided it preferred to site itself in the field adjacent to our garden, it left the concrete behind though.

However, I have never had (touch wood) any problems with the poly tunnel since we installed it in 2009, we've still got the original cover on it, and we don't have any rope or elastic on the outside of it.