I know I am not going to do a great job explaining this one, but here goes. In my living room is a small window alcove (5 ft X 3 ft) - meaning the floor of this alcove hangs out over the foundation. So outside, it pops out of the house -follow me? Meaning the floor hangs out roughly 2-3 ft from the foundation and about a foot from the ground.
Now that we some freezing weather here in Oregon, I notice the floor in the alcove is very cold. From the outside I can't tell if there is insulation in this floor or not, but the temperature of the floor tells me there isn't.
Finally- my question - Can I just attach some foam board to the underside of the exterior floor? Will this do anything to insulate or do I have to remove the old wood (that I can see), insulate, then reinstall wood? The wood on there now is old planking, should it be plywood? Since this is a overhang, it doesn't get rain, just cold. This is all made more difficult by the fact that the PVC gas furnace vent runs right below this exterior floor.