I just got back from doing some emergency storm-management. Earlier this year, mum got a greenhouse with polycarbonate panels (some sort of corrugated plastic laminate), but a fair number of the panels have blown out in the wind, since they're so light and flexible, and were scattered all over the garden. She also got a trellace put in, but it seems the workmen did a shit job of it; each 2*1.5m panel was secured just with 4 little screws, and two of them came loose, with one landing on her car. There was no damage to the car, despite the panels being pretty heavy, but I'll have to remount and brace the trellace so that this doesn't happen again. For now, I've tied up one of the panels with wire and left the other lying against a post. Of course, the trellace that I made is absolutely fine, and the gate that I did a fairly major renovation on is having no problems.