Allotment Gardening Advice Help Chat
Chatting => Design and Construction => Topic started by: al78 on January 06, 2018, 19:35
-
Over the last couple of years I have been helping a friend with her greenhouse. The panels were twin wall polycarbonate and no matter how many clips I used to secure them in, several would blow out during high winds.
After querying on here, I tried some No More Nails tape to stick them to the frame. That failed.
I then tried a silicon based sealant applied liberally between each panel and the frame. That failed.
I have recently tried drilling several holes in each panel next to the frame, then chaining panels together with cabel ties wrapped through two panels and the frame. That has just failed, with one panel pretty much wrecked as it was literally ripped away from the cable ties and thrown 50 meters away onto my plot.
I can only think the panels are not rigid enough, and the pressure force from the wind blowing parallel to the panel is causing it to bow outward, escape the clips, then the wind gets under it and away it goes. The next plan is to gradually replace the twin wall polycarbonate with 4mm solid polycarbonate. This is much heavier and more rigid. With any luck this will not bow outward in strong winds so the clips will be able to hold it in the frame. We shall see. It is rather frustrating as no-one elses greenhouse seems to suffer, although most of them appear to have glass rather than plastic.
-
Would it be useful to put debris netting weighted heavily over the greenhouse in winter
-
That may work, the current plan is to gradually replace the twin wall polycarbonate with solid polycarbonate which is stiffer. If that doesn't work it may be a case of removing the panels in autumn and putting them back in the spring.
-
Is it maybe a case that the frame is not squared up & that is what’s allowing the whole thing to flex? Or maybe the panels are too big & flexible, can each section be braced through the middle?
-
No it isn't perfectly square, water in the two gutters flows in opposite directions. Nothing can by done about that now, the greenhouse has been there a long time and has probably shifted slightly over time. I like the idea of putting something across to brace it, it is just a case of finding a suitable material that can easily be cut to size and attached securely.
-
In that case I’d be inclined to take the bull by the hornets & dismantle it, rebuild it square & add some aluminium struts down & across each window section before putting back the plastic. A big job but will save lots of time & frustration in the long run.
We had to take all the toughened glass out of my 8x10 greenhouse 2 years ago as the base had sunk in 1 corner & I couldn’t close the doors. It was a huge job but well worth the effort, I did not want the frame to twist & buckle & although in a sheltered position it was open to being ripped apart by heavy winds. See site owner Johns experience of that happening to his reasonably new greenhouse a few years ago in his blog.
-
I have a glass green house but a few panes broke so I replaced with that twin wall stuff, and yes a bit of wind and off they go , as you say they are just to flexible
-
It’s a game int it. Mine has a panel out at the minute. My glass greenhouse has not come through winter unscathed either. One complete side of the door, 3 pieces have been smashed by a flying plastic chair Repair man coming tomorrow