Step 1: A layer of grout over the concrete blocks and fireproof board.In accordance with Japanese Fire department regulations the 3 inch concrete block bust be filled with concrete and rebar, then installed leaving a 1 inch air gap between the blocks and the fireproof wallboard. Our mantle will also be Mount Fuji lava and is being cut now. It will be installed on top of the blocks in this picture.
To achieve the 3-D effect we are using black grout and the slabs of lava have been cut in various thicknesses.
Close-up of the stone. It looks somewhat like soft pumice but is very hard!
Event the overhead smoke containment wall (Japanese Fire Regs) is being done in lava. The actual ceiling will be done in black sheet metal over the fireproof board. We wanted a copper ceiling but cannot have it due to fire regs, but that is another story in itself!