Our house has a porch that was enclosed and made into a den. The floors get real cold in the winter so I want to insulate as best I can before it gets too cold. When I looked under the porch there is a layer of insulation tucked into the underside of the floor with some of it falling out through the torn up plastic sheet that used to cover it. This section of the house is accessible through our basement where there is also a cold breeze blowing through the top of the basement wall. So, I want to find the best solution for this dirt floor crawl space.

Some facts: Dirt floor, three walls of 3/4" wood paneling, the other side of the paneling is the outdoors. It is not vented but I am sure air is able to penetrate through the wood if the panels are not snug. The paneling touches the dirt floor. I will not need to access this site regularly.

So, should I re-insulate the ceiling and add a vapor barrier to the outside or install one prior to the insulation? What should I do with the 3 exterior walls? If I insulate, should it touch the ground? I do not believe water penetrates the room but I am not certain.

Any suggestions are greatly appreciated!