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How to make a pizza oven - part 2
In 'How to make a pizza oven - part 1' we looked at the steps involved in making the foundation and the base for your own wood fired pizza oven. In this article, we will walk through the rest of the process - making the floor, dome and chimney.
The first step is to make a layer of insulation on top of the concrete floor. This is absolutely critical for 2 reasons:
- The concrete will weaken and crack at the temperature the cooking floor reaches.
- The oven will heat up much more quickly if the heat isn't wicked out into the whole base.
I used a castable insulation, but a good cheap option is to use a 5:1 mixture of vermiculite and portland cement. I setup a plywood form and poured the insulation into it in 2 stages. First, a disk big enough for the oven to sit on, and then an extra square for the oven entry.
Another easy option is to use a square sheet of insulating board - I would recommend this approach, having done it the hard way!
Once you have poured the insulation and let it dry, pour a thin layer of sand over it to set the floor bricks into.
The Cooking Floor
The floor of the oven is made of bricks in most cases. Large, flat firebrick tiles may also be available from specialty suppliers.
I started by laying out my bricks and ruling the shape of the floor. I used an angle grinder with a diamond blade to trim the bricks to shape. It is also possible to come up with a design where the edges of the floor bricks are hidden, in which case you can save some time by not trimming the bricks.
Once I had the bricks cut to shape, I transferred them on top of the floor insulation layer. The layer of sand I had set up earlier allowed me to use a rubber mallet to tap the bricks into place so that they were all level.
I used 2 layers of thinner bricks, and after the first layer I set up the first course of the oven dome. The oven dome is not mortared down at all, so that it can freely expand when heated.
You could also use a single layer of thicker bricks rather than 2 thinner layers like I did - aim for a cooking floor around 75mm thick.
Next, I laid out, traced and trimmed the second layer of bricks, and set them up as well. For the actual cooking surface I used a 'herringbone' pattern of bricks, and set them at a 45 degree angle to the oven opening. This stops your cooking implements from getting stuck on any raised edges so easily.
Building the dome
Next comes the dome of the oven and the entry. The dome looks much trickier than it really is, but there are a couple of good methods to get the shape right.
One common trick is to build a dome shape out of damp sand, and build the bricks up around it. Once the brickwork is finished, the sand is simply scooped out.
Another method is to use a wooden semicircular form, sitting inside the oven, to get the angle of the bricks right.
I didn't use any forms, preferring to use a piece of string attached to the very centre of the cooking floor with a knot tied at the point the dome was to start. I held the piece of string tightly to find the right position for each brick, and used the mortar to hold the bricks into place.The bricks are normal red house bricks, cut in half longways with a hammer and bolster. The rough part of the cut is left facing outwards. Try to stagger the bricks each layer, so that a brick crosses over the join between the 2 bricks beneath it.
Before building much of the dome, I made the entry arch. This meant that I could fit each layer of bricks around the entry as I went along.
Once I had built the dome nearly to the top, I had to use a stick occasionally to hold some of the bricks in place but the mortar sets enough to grab each brick in just a few minutes.
For the mortar mixture, use 1 part portland cement, 1 part lime, 1 part fire clay and 3 parts brick sand. The fireclay helps to stabilise the mortar at high temperatures, and also makes it stickier.
When the dome is nearly finished, you will find that you need to cut your bricks into smaller pieces to fit them in. I used a bolster to break the bricks into manageable chunks. When your rings can't go any further, carefully shape one brick to fit into the space left over and gently tap it into place.
Insulating the dome
Once the dome is finished, you will need to apply a layer of insulation around the entire dome. This stops the heat from escaping, so the oven stays hotter for longer. You can use the vermiculite mixture for this as well.
Once the dome was insulated, I made the entry to the oven. This is just an extension of the front arch, made slightly larger so that you can fit a door inside if you want to. The purpose of the arch is to support a chimney, which helps draw smoke away from the front of the oven.
Finally, I had a steel chimney made up and attached it to the brick entry. You could do this yourself if you are handy with a welder, or have one made up by a commercial welder.
At this point, the oven is ready to start cooking! However it is best to slowly build up your fire, making just a small fire on the first day, then slightly larger and so on over the course of a week, until you have a full cooking fire. My oven takes about an hour and a half of a good big fire before it is ready to bake, but it holds the heat for ages. The fire is pushed to the side and pizzas cooked directly on the hot bricks - they are ready in less than 2 minutes, and absolutely delicious! I have written other articles recently about how to make a great pizza dough that you could cook in this oven as well as some ideas for pizza toppings.
Check out my blog for more pizza and other recipes!