We have a 12'x23' poarch that is 20' above the ground held up with brick columns. The poarch has 2 walls that are brick & 2 walls that are half siding & half screen with deck wood flooring. We want to replace the screen portion with windows. We are located in NC & our house backs up to woods with lots of birds & squirrels. What is the best way to insulate the underneath side of the poarch floor?