I am writing today in praise of twin wall polycarbonate glazing materials. We are having trees removed on our property due to size (large) and shade (dense). A top from a multi topped western red cedar angled away from its fall line despite a line and undercut, and fell across my cold frame two days ago. The in-ground portion of the frame is 2x4 lumber with ground contact plywood (1/2 inch) sides on both sides of 4 inch foam panels. This frame survived. The above ground movable tops were wood 1x2 and 1x4 materials, glazed with twin wall. These are now kindling. The twin wall, on the other hand, while it was punctured in spots by branch tips, and crushed where the main trunk hit it, remained in intact panels. There was very little damage to the pots underneath as a result. The panels are in good enough shape that they could be removed from the crushed frame and laid across the base to protect the pots underneath until we rebuilt the above ground frames. It’s not great, but I won’t lose the plants this winter. I am totally impressed with this glazing! Kathleen PNW Coast on a cool drizzly day