would you use polycarbonate panels for a garage roof?

[Kolesar]

1. I made cold frame "lights" out of that product

I bought them as surplus "cut offs" from the local greenhouse builder. Nice product!

My hunch is that you would have to support them at close intervals or they will flex. I don't think they would work over rafters with a 24" spacing.

Comment: The benefit I was interested in was light weight compared to 1/4" plywood. Very good in that respect. A possible downside in construction is flexibility if used for roofing in snow country.

Unless you really need to control the temperature in the barn, you could use something simpler like the wavy fiberglass panels that are ruffled like Ruffles potato chips. You could wait until March to keep some plants in there at temperatures above freezing.