How much insulaction value is a bail of hay? I want to put it around the back wall of my solaruim that I am attaching to the house this week. 24 foot along the house will be only thin skirting . I will build a wall when I have the money to do so. But for the time being I want to use hay or some other thing that want cost much. If this will work, do I need to cover it with plastic?