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Saint Paul Bread Club

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Location: Quest for Ovens / Oven Types
 

Oven Types

There are several types of ovens in modern use. I mention some sources here, but you should look at the Oven Sources and Oven Links for more complete information.

How Ovens Are Built

Ovens have an ancient history. Ovens built in the modern day tend to be of a few different kinds. (This is pretty much regardless of who builds them.)

  1. A single cast piece of concrete.
  2. A single prefabricated oven unit.
  3. Multiple prefabricated ceramic parts.
  4. Hearth slab and fire brick.
  5. Hearth slab and cob (clay).
  6. Stacked bricks or dry-laid stone.

There is also a question about whether the oven is a “white oven” or a “black oven.”

This is a distinction seldom drawn because most people never care about it.

  • A white oven has the firebox separate from the baking chamber, and the fire can be going while the oven is in use.
  • A black oven has no separate firebox, so the baking chamber gets a certain amount of soot and ash from the fire. The fire is usually removed and the hearth cleaned before baking to keep the ash off of the baked goods. If the oven is used for pizza, a fire might be maintained around the edges or in the back to keep the oven hot during baking.

How Ovens Are Used

One key question you need to know before you build or buy an oven, is how you are going to use it.

  • Bread oven
  • Pizza oven
  • Both

A bread oven needs to hold heat for a long time, but has a lower operating temperature than a pizza oven. A pizza oven at 800 degrees can cook a pizza in 90 seconds. A bread oven is better at 350 to 450.

Oven management, where you learn to bake the right things at the right temperature, is one of those skills that you will have to learn to successfully operate a brick or cob oven.

In general, bread ovens have more mass, take longer to heat, and keep their heat longer as well.

A pizza oven may also be designed to keep a fire going on the inside as long as pizzas are being baked; this helps maintain the temperature.

Common Features

For wood-fired ovens, there are some common features that sometimes take people by surprise.

Where is the chimney?

In wood-fired ovens, the chimney is outside of the oven itself. It will often be placed outside the oven door, but between the oven door and the front facing of the oven. That’s because when the fire is burning inside the oven, the circulation of hot air is forced to go over the entire oven ceiling and then out the door of the oven. Directly venting the oven interior would just result in heat being lost.

Where is the ash dump?

A wood fire produces ash. It has to go somewhere, and you want it out of the oven if you are baking directly on the oven floor. Often there is an ash dump slot just outside the oven door (about where the chimney is). A metal trash barrel can be placed underneath to collect the hot ash as it is raked and brushed out of the oven when the fire is done and the oven is ready to be used.

What kind of roof?

An outdoor oven is a kind of building, one that would suffer degradation from the elements. For this reason, outdoor ovens often have roofs. There is no standard for the roof type, but can be a shed roof, an A-frame, with or without a substantial overhang (for protecting the bakers).

It is one of the elements where costs and benefits need to be considered when planning an oven.

How high should the oven floor be?

This doesn’t get discussed much, but this is actually an ergonomic issue in tension with a cost issue. There must be some kind of base for the oven. This serves as part of the thermal mass of the oven. It can also be used for fuel storage, and as part of the ash dump. (See the pictures of the different private ovens for some examples.)

Generally you want the floor of the oven to be about waist level, so that you can use a peel to get bread into and out of the oven with the least amount of strain on your back and arms.

The cost of the height of the base is partly based on the volume of material that it takes to build it. Kiko Denzer has several ideas on how to find material to use for little or no money. If you want to take the direct approach, concrete blocks are often used for the base.

Concrete Ovens

The only source I know for prefabricated concrete ovens is here in Minnesota: Artesian Ovens.

(There might be others, but shipping such large and heavy items would tend to make them uneconomical.)

Prefabricated Ovens

There is one source I have found for an entire oven: Vesta Fire USA

It is a stainless steel enclosure around a fire brick interior. This is for a pizza oven that can operate at temperatures of up to 950 degrees.

Prefabricated Ceramic Parts

There are three sources of these that I’m aware of. (You would need to determine for yourself how to get these ovens installed for you, because I don’t know.)

Apparently one of the advantages of the ceramic ovens is that they use less fuel than a brick oven because of the nature of the ceramic. (I don’t know how to verify that claim, but it’s worth considering.)

Brick Ovens

For ovens built from brick, there are designs that are merely a careful stack of bricks (as few as 100 and as many as 500), domes (a traditional Italian style) and barrel vaults (many of which are known as Alan Scott designs, since he was most well-known modern proponent, designer, and builder of such designs).

There can be a lot of parts that go into building a brick oven. If you can salvage any of the parts, you can reduce the construction cost. Expect parts costs to be $2000 to $5000.

For the better built brick ovens, just the hearth slab can be three layers of different materials that make the oven more efficient.

There is also an interesting range of complexities of brick oven. Some are, shall we say, a bit more crude than others.

Some points along the spectrum of crude to fancy:

photo of Alan Scott

Photo of Alan Scott used with permission of the photographer, Art Rogers.

Cob Ovens

Cob ovens are in some sense individual works of art. They are much cheaper to build than brick ovens. In the right environment, they can be built entirely from materials available on-site.

  • Sand
  • Clay
  • Straw
  • Rock (or brick)

For this reason, there are many garden ovens that are built from cob, because all of those materials might be found around a major garden. (Look in the Oven Links for Cob Ovens in Gardens for some links. You can also go to Google and search for 185,000 links that might be appropriate.)