In the Begining There Was A Base

So in the beginning I had to start somewhere. Since the brick oven was what started all of this I figured the clay oven was where to start. With that I had to come up with several questions and answers. These are the questions that I had to figure out:

1. How large of an oven do you want? Otherwise put, how much food do you want to be able to cook at one time?
2. How high do you want your oven, or how far do you want to bend down?
3. What direction does the prevailing wind blow?
4. What to build the base out of?
5. How far away from a house or structure is the oven going to be?
6. How do you want to cook in the oven? Should it have a chimney? Should it have an external door?

I know that seems like a lot of questions and some of them seem basic while others may not make sense but I promise that each question is important and I learned the hard way. So let's start thinking about these questions and see why they are all important.

How large of an oven do you want? Otherwise put, how much food do you want to be able to cook at one time? This seems simple but, every other decision you'll make from here on out is based on this choice. What this comes down to is how much food do you want to cook at one time. As I said in my first post my wife and I have eight children so you can imagine how much food we have to cook sometimes. I opted for a large oven. Most clay ovens that I have read about were a maximum size of about 28 inches in diameter. I did some measuring and calculations and decided that this was too small for the times when we were cooking a lot. In a smaller oven the problem was putting the food in and pulling it out then putting more in and since it's a slow cook what's already cooked would be cold by the time the next items would be cooked. So I opted for the largest clay oven I was willing to build the first time out. I decided on a 48 inch internal diameter oven. This is important because you have to start with the internal oven size and add on thickness of the thermal layer, the insulation layer and finish layer. Add all that together and that's how big your base needs to be. For example my oven is 48 inches in diameter then my thermal layer is about 7 inches thick, so that would be 48 inches and 14 inches, 48 + 14 = 62 inches in diameter. The number to add is always double the thickness of the layer since the diameter is double the radius. So you measure from the center out and then double the layer thicknesses to offset the correct diameter measurements. Now add a 6 inches thick insulation layer and a 1 inch thick finish layer, 12 + 2 = 14 inches. So 62 inches and add 14 inches, 62 + 14 = 76 inches in diameter. This is the required size of the base in order to support the 48 inches internal diameter of the oven. You'll need to make these calculations before beginning the construction of your base.

How high do you want your oven, or how far do you want to bend down? This is simple but important. If you build your oven on the ground then you have to bend way down every time you get into the oven. With my back injury I was not planning on bending down like that. So I decided that I wanted the floor of the oven no lower than about my waist. You'll have to make this choice but keep in mind that if your oven is maintained it can last for years so consider your physical condition now and the possibilities in the future. I had to learn this the hard way.

What direction does the prevailing wind blow? I know this seems like an odd question but, if the wind can blow directly into the oven door than ash and embers can be blown out as well as all over any food that maybe cooking in the oven. A cold wind blowing into the open hot oven can also disrupt the thermal dynamics of the oven. I also had to learn this one the hard way. Now in my case the door is facing the sitting area and entrance to the house but, this aligns the door with the west to east winds that we get here. However in my case this was the best overall positioning so as I'm building my kitchen I have to take this into consideration and make sure to build wind blocks to solve this issue.

What to build the base out of? This is really up to you and it seems to be a very personal choice. My kids and I went out to the desert to collect rocks to use to build the base. While looking for rocks we came upon discarded urbanite. Wait, what was that word? Ya I know it's just a fancy way of saying broken up cement, but it really means any man made stone like material of which cement is only one. So we collected rocks and the urbanite to use as the stacked stone of my base. You can use just about anything you like such as bricks, block, stone, cob, adobe, metal and even wood. The choice is yours.

How far away from a house or structure is the oven going to be? This seems strange to ask but it serves a purpose. As I learned the hard way that I can no longer carry large trays of food and move the door. I need a place to set things down. my oven is about 40 feet from my door so I had to add a counter into my design for the base. You'll have to decide what kind of work space you'll need. Keep in mind that if you think you'll have just enough room you will run out. So make sure to plan ahead because as soon as you start using your oven you will want to use it more and more. There is nothing like food from a wood oven and you'll learn to appreciate that very quickly.

How do you want to cook in the oven? Should it have a chimney? Should it have an external door? Why am I asking this question in regards to the base of the oven? Well again this is something that I learned the hard way. If your base is lightweight and not able to support the weight of a chimney or additional insulation layer then your base will fail. My advice is if you can build it with a 2x4 then use a 2 foot in diameter log to make sure it will never fail. In other words overbuild, overbuild, overbuild. Everything will depend on your base. Ovens that are built on a solid base and maintained have been known to last well over a decade.

So with those questions answered you'll be well armed to begin construction of the base of your oven. Below is a diagram of the design that I used for my oven base. We used the rock and urbanite as stacked stone that we mortared together with a thick clay mud mortar. We then filled the internal void with rocks in the bottom and a damp dirt and sand mix. Be sure to tamp the fill as you put it in. Once the internal void was filled and tamped down solid my base became rock solid. My base is so tough that before we built the oven on it I had to use it as a workbench to repair my car. This required me and a friend to beat pressed parts out and reshape parts with a sledge hammer. My base didn't even flinch. At this point I can honestly say that I think it would stop a car dead in it's tracks.



Once you have your walls built and the internal void filled you'll need to decide whether to cover your base with cob or not. I chose the cob as it will allow me more options for decor and design and allow me to make a waterproof coating when completed.

Next I used a ring of cob on the outer edge of the ring of the base. About 3 inches thick will allow you to fill the top with sand in order to be ready to build the base of the oven and eventually the oven. I would recommend not adding anything else to the top of the counter area until after the insulation layer is added.