Chimney stability question Pompeii Oven Construction Discuss Chimney stability question in the Pizza Oven Design and Installation forums; I'm thinking of building an almost freestanding brick chimney for my oven. The vent mount will be firebrick on top ...

[charliefarley]

I'm thinking of building an almost freestanding brick chimney for my oven. The vent mount will be firebrick on top of the arch and have clay flue liners bedded on top.
As I was thinking of doing an arch facade of reclaimed bricks in front of the outer arch, I thought why not build the whole chimney stack around the vent and flue so it is free standing and not putting any extra weight on the arches. Another idea I had was to put a lintel across the back of the two side walls so that the back of the chimney is not resting on top of the dome.
This effectively means that the whole chimney would be balancing on two side walls.
Even if I taper the chimney do you think this would this be stable?

[dmun]

This is absolutely the way to go. Except for the lintel in the back, almost every masonry fireplace is built like this. A couple of details: There should be a half inch of free clearance between the flue tile and the brick exterior, and whatever you use for a chimney cap should have some kind of slip plane to allow for expansion of the flue stack when it's hot. I wrapped mine in aluminum flashing before casting the concrete top.