Non-flammable roof sheathing?

[rwiegand]

Thinking about the house, I'm hoping to build a structure with steel studs, use a cement backer board for the walls, finish with stone on the cinder block bottom and tile on top. I'm not so sure about the roof. Slate tile would be, I think, my first choice for roofing material (though perhaps three materials in a small building will be too many), but I'm not sure what to use for roof sheathing.

I'm not sure that a cement board like Durock will hold roofing nails. Our climate precludes Hardie backer for outdoor use. So what do you use? I suppose plywood sheathing on top of a Durock layer would work, putting a non-flammable surface between the oven and the wood.

[Gulf]

I think that a properly installed oven should be as safe as a home fireplace with any roofing material imo. There being said, there are plenty of options for metal roofs that look like slate or tile .

[rwiegand]

I'd like to do real slate roofing shingles.

When we rehabbed our house the inspector insisted on fire resistant materials from the top of the fireplace to the ceiling. I expect the roof deck will be within a foot of the top of the dome, so I'm anticipating a similar need for fire-resistant materials. A small garden structure like this is exempted from the permit requirement, but I like to build to what the code would be should questions arise later.

[Chach]

You could do 2 layers of drywall for a 2hr fire rating then plywood on top of that but it seems like a lot of material to go through. Drywall is not that expensive but if there is a leak in the roof drywall soaks it up and cement board would be better. There is fire treated lumber as well but not sure if that would suffice. That is a building code here in Chicago when using wood framing in a commercial environment. This is a good question.