Previous owner of our house improperly installed a metalbest chimney system. He squeezed the pipe through 2 floor joists between the 1st and 2nd floors, there is 10.5" between the joists instead of the required 12". To compensate he created a makeshift heatshield using aluminum flashing tacked to the sides of the joists with fiberglass insulation between the layers to protect the joist from heat of pipe. I attached a picture that is hopefully helpful. I've monitored this over the winter here and it seems fine, but I'd be concerned about how it would stand up in a chimney fire. I see two solutions, the easiest being to create a better heat shield by attaching a thin piece of aluminum to the joist but with a ceramic spacer to hold it off the joist so it can properly dissipate the heat. Option 2 is opening up the ceiling and properly blocking off the floor joists. This will be tricky as I'd have to block off 2 joists and the next one in line is the rim joist making it very awkward to re-frame properly. Has anyone created a heat shield to reduce the clearance of metalbestos from 2" to 1"?