Building a Pizza Oven

With COVID-19, our lives changed. Instead of traveling and spending some of our valuable time on vacation, we had to stay at home. So we did what many decided to do too: Home Improvement. What started with a small concrete slab for our BBQ grill ended up becoming an elaborate projected moving ton of stuff from the ground, gravels, concrete, and other building material. At the end of the 3 months project, I was in great shape. I lost 10 pounds and had nice muscle. Well, that was back then. You know too well what winter with Thanksgiving, Christmas, and New Year can do.

If you read this blog, then you know that I am a passionate bread baker. Still, I was surprised when my wifey suggested that we should get a pizza oven. A pizza oven can be much more than an oven for pizza but also baking and cooking.

We will discuss here shortly what and why we chose our oven. You will see what we built and later what we cooked/baked.

Woodfire Oven

100 to 200 years ago, people still cooked a lot on the open fire and wood stoves/ovens. Electricity and gas made these ovens obsolete. The new ovens were user-friendly and did not require firewood chopping, storing, and lengthy preheating. Today we can simply turn on the stove, and almost instantly, we can cook.

Stone ovens were probably used as early as the so-called Neolithic (11000 years ago. The origins of baking in wood ovens come from Sumer and Egypt via the early Mediterranean to Europe. 6000 years ago, beer brewing was an essential element of their economy. The Sumerians and Egyptians brewed over 60 types of beers, even some for export. At the time, they made beer from bread. Women dominated the bread baking and were, therefore, the beer brewers too. Egyptian texts mention at least 30 different products made from bread, indicating how widespread and appreciated it was. Their loaves of bread were made from wild yeast-generated sourdough and lactic acid. As ovens, they used Clay pots. The inside was filled with wood or charcoal and fired for several hours until they were hot enough for the baking process. One can find the tandoor-type of ovens in Afghanistan, India, Turkey, Armenia, and nearby regions.

The Greeks and later the Romans perfected the art of baking and technology. The Romans had established an industrial type of bread baker producing a thousand of loves a day. The bread was an essential part of their food source for common people and necessary for their army. The large Roman Empire had to maintain robust logistics to supply the front troops with all the necessities. Soldiers carried especially baked hard-beaked loaves of bread with them if the enemy disrupted their supply chain.

Each medieval convent or abbey had a baking facility, and the monks baked large quantities of bread (and brewed beer too). With growing demands, many large grain mills opened.

How a Woodfire Oven works

Gas and electric ovens control the temperature with a thermostat and a heating system. Most wood-fired ovens are heating up the inside of the baking/cooking chamber. Three types of heat transfers can be distinguished:

1.) Direct heat (typical for meat): A grill over ember (some indirect heat comes from the walls)

2.) Convection heat (typical for Pizza): A small fire on the side while cooking on the cleaned side. Hot heat travels from open flame to the “colder side” and browns the top. (Indirect heat from bottom tiles and top walls).

3) Indirect heat, radiant heat(Typical for baking) from bottom and walls:

After the wood has burned out and the ember was removed there is no heat source available. The heat for cooking is therefore retained inside the walls and floor tiles.

Choosing Woodfire Oven

There many types of wood fire ovens and you can find a vast amount of information on the internet.

The first question you need to ask yourself is what you want to cook or bake. there are various types of oven shapes: Tube, Dome, Square, and various types of materials: clay, fire bricks, refractory concrete etc.

Here we discuss only commonly dome ovens, also known as pizza ovens.

If you are interested in a Pizza oven only and for a small family, then you could go for a small Napolitana type. These ovens are not high and therefore have a smaller volume, which means they heat faster up and irradiate heat from the wall. Tuscany Pizza ovens are a little higher and thus have more volume. Many people consider them more versatile for grilling and baking, which was my choice.

At first, I wanted to make a full-fire brick oven, also called a Pompeii oven. As it turned out, getting all the building materials in Georgia would have been too expensive, due to hefty transport costs were added. Also, a brick oven is time-consuming. Luckily one can find on the internet several providers that sell kits for building various types of pizza and wood fire ovens. I will give links to several providers. In the end, we selected for a PRECAST WOOD-FIRED PIZZA OVEN KIT.

Figure: Heat Retention of Brick oven (blue) vs Refractory Concrete Oven (yellow). X-axis: Time (min), Y-axis: Temperature (C) The heavier brick oven retains the heat for a much longer time than the lighter cast oven. Obviously, the heat decay depends on the type of material, insulation, and auxiliary weather conditions.

Our precast oven consists of four sections made from a high-grade refractory castable, reinforced with stainless steel fibers for superior strength and durability, rated to over 1350°C. This oven can be constructed considerably faster than a full-fledged brick oven. Also, it is significantly lighter (1600 lbs. vs. 2500 lbs.) and can be installed on top of a solid welded steel frame table. The heavier Pompeii oven requires a solid center stone concrete stand and concrete foundation. Another consideration was the heat up time of 1.5 -2 h vs. 2 – 3 hours to 400°C. Of course, the lighter oven has smaller heat retention, which results in a faster cooldown time from 400°C to 70°C of 36 hours vs. 60 hours; in 12 h or from 400°C to 220°C vs. 300°C. We will discuss these retention times later as they are essential for cooking and baking. Unlike in conventional gas or electro ovens, no additional heat source is present once the fire and ember are removed.