I don't know if different types of plastics are used, but.. I am thinking of the same plastic that people who live in places like Tahoe use to shield their entries/porches during winter. We used to use "clear construction plastic", I think it was a 6mil plastic, to hold up to wind. Only other thing I could think of being a problem, if it's not made specifically for a greenhouse, is crumbling to bits after so much exposure to directly sunlight.

Sounds like a plan!

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