Q: I am building the base for your 28" Mattone Cupola. I have finished the slab base on top of the cement blocks. Next step is the fire brick and standard brick application. Question: Can I use a granite slab instead of the standard brick? I would build up around the fire brick with appropriate cement so the height of the cement and granite is level with the fire brick.
A: You want to stay away from materials like Granite, Slate, Marble, Limestone or Soapstone in the front of your oven. The reason? They tend to break under the high-temps at the front of the oven (and they are usually in larger pieces, not smaller, more forgiving pieces of masonry).
Now, I’m not going to poo-poo on your parade - I think those materials are beautiful and look amazing at the front of the ovens, but I do want to give you a heads-up about the cracking / breaking issues I’ve seen before you attach those materials to the oven with High-Temperature mortar.