I have an old wood home raised several feet off the ground on brick pillars. At this point you can see the ground through some of the floors. I'm wondering if it would be effective to insulate the floor by putting foam panels across the joists to create an insulated air space (not looking for great insulation, just an improvement). Would there be a moisture concern? It is a waterfront home (on a bay, mildly salty). Am also considering skirting to enclose the area.