Tips for building a chimney on a pizza oven - Thermal expansion and expansion joint

Thermal expansion:

Most materials are subject to thermal expansion: a tendency to expand when heated and to contract when cooled.

Most Portuguese manufactures of wood-fired pizza ovens build their chimneys in direct contact with brickwork. We strongly do not recommend this procedure.

The force exerted on a chimney pipe or damper exerts tons of pressure ( stress ) on the steel as temperatures reach up to 1000 F  causing the steel to expand and cause structural cracks to the surrounding brickwork. 

Our ovens have built-in protection against the hazards of thermal expansion known as an expansion joint.

We separate the steel damper completely from the oven and it is loosely fitted over the chimney brick stub leaving space for the hot gases to expand. 

https://www.youtube.com/watch?v=NVkO1Dww1e8

Why does food taste better in a wood-fired pizza oven?

Our ovens are made based on thermal mass. Thermal mass soaks up the heat - like a battery building up to full charge. When the oven is hot ( and it will get very hot ) the heavy dense oven walls release the heat slowly for hours. Food is cooked not only by the hot air but also the radiant heat from the hot dense bricks and hot floor. A steamy atmosphere produces a more flavorful and chewy crust while keeping other foods moist and tender. The triple combination of radiant, conductive and convected heat also speeds cooking.
www.domeovens.com