Is in that such entity as a fireproof board you can buy to use similar to drywall around furnaces conceivably? impermeable? ...

When the ground is frozen and we find...
Answers:    Its 5/8 in drywall or type x. That should tender you your fire rating that you need.If you want to use 5/8 greenboard for the extra moisture you can,but its still not "hose proof".
Plumbers or general public who no just about...
Metal.