<<Fleecewife, how does your polytunnel stand up to the strong winds? We are wanting to have additional housing for future and wondering about the option of having a livestock polytunnel, but it would be at 1100ft and is very exposed here so wondering how suitable an option it would be.>>
Hi Blackface (oops sorry - Black
sheep - modified
)
Ours is a veggie tunnel but with plenty of ventilation, so it can double up for the month of lambing. We are at 1000' and windy too, so we have gone for a Northern Polytunnels product. They do the livestock type too. The hoops and uprights are made of thicker metal than the norm, and a slightly greater circumference too, which gives added strength against crushing. We also have all the extra bracers plus crop bars and base rails, all of which add strength. Part of a tunnel's strength is in its flexibility - it's amazing how much the sides move in a gale
We also surrounded the tunnel with 6' high windbreak netting, which fits around our veggie garden which is between the tunnel and the windbreak, so both the veg patch and the tunnel were sheltered. Our hedges have now grown enough that this year we have begun to take down the mesh - which is shredding after about 15 years.
Not long after we put it up (9 months
) the cover blew off, but it was because we hadn't put it on correctly - you wrap laths around the bottom of the polythene and stretch it as tightly as possible before nailing it to the base rails (or side rails with the mesh side option), but we had turned the laths the wrong way
. We didn't repeat that mistake
. That was in an 80mph wind, but it has withstood 100mph winds without damage. It was the side opposite to the direction of wind which blew off, so the wind must have been creating a huge vacuum on that side, rather than pushing on the windy side. Also it was a southerly gale, and our tunnel lies east-west (so end on to the prevailing wind). Southerly gales are rare here so we would orientate another tunnel east-west again.
We have never been able to brush the snow off ours as it's 12' tall and 21' wide, but properly tensioned and with the sturdy hoops it's always been ok. Even when the snow slides off and makes a deep drift pressing against the sides, it's been ok - looks alarming from inside, but stays up.
I don't know how the livestock tunnels perform, but I would imagine that they would be less likely to collapse or blow away because of the mesh sides allowing some wind through.