I would caulk and paint with a porch paint .You can get really cheap paint at lowes in the mess up section .I paid 5.00 for a gallon and that would do your coop. It keeps the drafts out and easy to clean . Very nice coop .
You just have to call around .Check with your local organic store . Lowes and Home depot .I buy mine from a co-op that sell horse feed cow goats everything .You should have one there .Check with your ranchers and see were they buy there feed .
Good Luck