Pic roofing sheets in cold frame design / hoop frames

[Hector]

Have any of you folks used these. I've been told some fare better with UV degregation than others...and some retain flexibility better?

[Hector]

[squeezyjohn]

Do you mean polycarbonate (PC) roofing sheets?  The corrugated ones are generally rigid and brittle but can be shaped using a hairdryer to heat them - I don't know how they'd fare on a windy allotment site - they act very much like sails so if you were to create a tunnel from them they'd have to be closed at the ends somehow and very securely attached to the ground.  I think it would be safer to try and construct something square based around a frame and the kind of polycarbonate that they use in plastic greenhouse panes.

[Hector]

Thanks Squeezyjohn. I'd seen these and thought very clever but wondered if I could do a taller version.

http://www.lavenderandleeks.co.uk/shop/grow/clocheborder-hoops/