
OK it's not a sink hole, but almost as puzzling. The cavity is inaccessible from the house without removing drywall and is about 3x3x8. Inside the cavity, the exterior wall has insulation but the other 3 walls are bare which certainly doesn't help heating and cooling costs.
Any ideas why this would be there? I'm assuming that a simple sheet of plywood and some insulation on top would be sufficient. Do I need to use a vapor barrier above the space since it isn't ever occupied?
Thanks.