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Pizza Oven Floor Design

There are a couple of good reasons for you to understand pizza oven floor design. Whether you are going to be building a pizza oven or buying a complete pizza oven—either refractory or steel, understanding the trade-offs of different materials and designs will help you make the right purchasing decision and become an expert at managing your oven, and if you will be building or designing an oven, this knowledge will help you move forward ready to make the right decisions.

Pizza oven floor design is mostly centered around your choice of material, and the thickness of that material. Let’s start with material. A majority of pizza ovens, whether you are talking about a $400 Ooni Fyra 12 or Koda 12, or a $20,000 Naples style brick oven, are built using one of three basic materials—cordierite, firebrick, and Biscotto. Let’s talk about each one. We’ll discuss steel baking stones at the end.

Cordierite is inexpensive and resistant to thermal shock (rapid heating up and cooling down of refractory materials), which makes it the right choice for smaller ovens (think Ooni and Gozney) and even some of the lower end mid-size steel ovens (think no-brand ovens made in China). It’s also the choice of material for virtually all inexpensive pizza stones for your conversional oven. It’s very hard, and not very porous. And it’s pretty durable.

If you look at a basic Ooni oven, it has a simple, thin (0.4″) Cordierite stone that is mass produced in vast quantities at extremely low cost in a high-tech factory in China.

But Cordierite has some very serious drawbacks. Its thermal conductivity is very high in the context of pizza making. That means that heat stored in a cordierite oven floor quickly transfers its stored heat into the pizza—often causing pizzas to burn when cooking at high, Pizza Napoletana temperatures. And because cordierite transfers its heat quickly, it can essentially “pour” its stored heat into one pizza, without storing enough heat for a second pizza. Which means that the stone must be re-charged again before making a second pizza.

Note that this discussion is relative to the context of a high temperature pizza oven, not a convention oven. In a conventional oven, you could make the case that the thermal conductivity of a cordierite pizza stone is too low of pizza making, and that a pizza steel is a better choice to pizza making in a conventional oven. Though a cordierite stone is a good choice for a general-purpose baking stone in a conventional oven, for baking bread, cookies, pies, cakes, etc.

A Biscotto stone, on the other hand, has much lower thermal conductivity and is better suited for high temperature, 800-900ºF+ baking. Biscotto stone material is porous and made using natural clay, and it holds heat better and releases heat more slowly than either cordierite or firebrick.

Firebrick production starts with the selection and preparation of refractory materials, including alumina, silica, and refractory clay, which are processed into a homogeneous mixture. This mixture is then molded into various shapes such as rectangular bricks, tapered arch bricks and cooking floor tiles, and then compressed. After a thorough drying process to eliminate excess moisture, the bricks undergo a high-temperature firing in a kiln, exceeding 1,000 degrees Celsius. This firing induces chemical changes, leading to sintering and the formation of a robust, heat-resistant structure.

The thickness of the pizza oven floor determines its thermal mass, and the balance of how long it takes to full heat up, or charge, how quickly it becomes ready to make pizza from the start of the oven firing, and how long it holds its heat. It’s important to note that there is a difference between the temperature of the inner facing part of the cooking floor and the outer edge, where in the initial minutes of firing the inner face can show a 900ºF temperature using an infrared thermometer, while the middle and outer edge of the floor are much cooler.

For scale, a 12″ Ooni oven cordierite floor is 0.4″, a mid-size oven floor will typically range between 0.8-2.0″, a full-size pizza oven floor is usually 2″, a commercial pizza oven is 2.5-3.0″, a residential bread oven is roughly 4.5″ and a commercial bread oven floor is 8″ or more.