Hollow smoke shelf???

[freeman.public]

I have a new masonry fireplace under construction right now. They just built the firebox, set the damper, smoke chamber, and first flue tile. We are waiting the next county inspection. Where I would expect to see a flat or slightly concave smoke shelf is just an empty cavern. There is just an airspace between the back of the firebrick and the back wall of the fireplace. I asked the folks building the fireplace, and they said this was normal. Every drawing I have seen of a fireplace shows a flat or shallow smoke shelf. Mine is just a deep "V" that goes down about a foot. Is this OK? (It is a traditional fireplace, not a Rumford.)

p.s. My other two masonry fireplaces have a flat smoke shelf.

Thanks.

 

[elkimmeg]

Has the county finished inspection? make sure behind the fire brick the space id filled solid with masonry. Also the space in the front where the angle iron is completely sealed so that heat and fire does not find a space to get into your framing members.
This is a common areas most masons neglect. It is hard to picture what you are asking. Without me personally seeing what they are doing I cannot answer you question about triangle