I'm thinking about buying a pre fab garage on skids with a wooden floor to store my T Bird so I have room in my shop to work on other projects. 12 x 20 should be ok. Debating on going with a metal roof with vapor barrier and metal siding or shingled roof and T5 wood siding. I am concerned about moisture condensing with a metal building. Less maintenance with metal. Either roof will outlast me but will have to paint wood siding eventually. Not a huge deal but something to consider Opinions?