I need to build a heat shield between my wood stove and wood stairs which are about 4 feet away. Originally I was going to just hang a few large pieces of sheet metal, with air gaps in between. I am sure it would work fine, but I assume it wouldn't be much harder to build a more permanent solution. What about a wall made of metal studs and fire proof drywall on both sides. Or even two walls, with an inch or two in between? Or....whats the correct way to do this?