How to build a wood fired clay pizza oven

Or at least, how I did it….

I should set the scene a little. There are several pivotal life moments I remember with absolute clarity.

• My mum’s tray baked pizzas (made using tomato paste)
• The day I discovered Parmesan cheese (and some years later when I discovered real Parmesan cheese)
• The first time I ordered a 12inch pizza at the newly opened Pizza Place in Bognor (circa 1985) and ate it. The secret I happened upon was, eat fast so you stomach doesn’t know what’s hit it.
• My first ever takeaway pizza (I carried it home under my arm like a book, only to find that all the toppings had slid off).
• My first monthly pay check. I worked out I could afford takeaway pizza every night of the month.
• My first ever Domino’s (at my aunt’s flat in London) in the late eighties. Amazing.
• The first time I made my own sourdough pizza crust.
• My first Pizza Pilgrim’s pizza.

Yeah, I like pizza. Pizza is the food that can always be different, can be simple or complex, but when done well is delicious.

So one of the first things I wanted to do once we got a garden big enough was build a pizza oven. There are some good reasons for building an oven. Firstly, you can make pizzas in it. Then you can use it for bread, roasts, casseroles. Weirdly anything you’d use a regular oven for.

I remember seeing a River Cottage episode where they built an oven out of clay, and the thought has been rattling around my head ever since. So after much internet information binging, I decided to take the plunge.

Stage one: The plinth.

I’m super impatient, so I ignored all the advice about laying a concrete slab and building foundations and decided to build the plinth on top of the patio area in my garden. I didn’t build the patio, so I don’t know what’s underneath it, but hopefully it will take the weight.

I managed to buy some cheap concrete blocks from my neighbour — about 65 of them. I only used around 40 in the end.

Because I’m quite lazy I settled on a size of 120cm X 150cm. Laziness made me stick to a size dictated by the length of available lintels (for supporting the base) and the length of concrete blocks (to avoid having to cut too many of them).

I decided to make the plinth four courses high, although the last course sits on top of the lower part of the base, forming the walls for the insulation and hearth layers.

I inserted the lintels at 60cm intervals to support 60cm2 concrete paving slabs.I also elected to build a decorative arch to form an entrance to a wood store under the oven. The previous owner of our house had been a keen collector of bricks, so all of the bricks for the arch I dug up from the garden, minecraft style.

Making the arch was fun. I sketched out the shape on cardboard, tested the size with the bricks and then used old pallet wood to create a former to build the arch around. It seemed to work!

The paving slabs were mortared on to the top of the lintels and blocks (and then expertly tested by Toby).

I then laid some more bricks (Minecrafted from the garden again) on the arch. Looks half decent from a distance, but don’t show it to any professional bricklayers.

The next stage involved drinking wine. This is a skill I picked up in my late teens, so both Laura and I felt able to share the responsibility of this one.

Wine bottles make an excellent insulation layer. The idea being that the heat from the hearth shouldn’t leatch out through the concrete paving slabs, and therefore ensuring the oven stays hotter for longer. One adage I’ve constantly found whilst reading up on this subject is, you can’t have too much insulation. Or in my case, wine.

Now for the hearth. So this caused me a great deal of stress. What kind of brick to use?! Firebricks are the best option, but cost £2.50 each. I need 50 bricks, so £125 + another £50 for delivery was out of the question. Others have used reclaimed storage radiator bricks — unfortunately there weren’t any available in my area.

In the end I decided to buy class B solid engineering bricks. They’re baked at very high temperatures, which makes them super hard and they don’t have any holes in them. So whilst they’re not ideal in terms of the correct material for an oven, given I’m only going to be firing it up a couple of times a month I decided that they would be fine. I also reasoned that after a couple of years, I may want to rebuild a brick pizza oven, so I could start saving now!

I laid them on sand in a herringbone pattern (to avoid catching the pizza peel on the edges). This proved to be fiddly, but I got quite good at cutting bricks with my angle grinder by the end.

Can you spot the rookie error? More on this later.

The Dome!

Exciting bit now! I went and bought 175kg of terracotta clay from a pottery supply shop near me (about £87), and 14 bags of sharp sand.

The clay for the first layer should be 1:2 clay sand mix, and the only way to do this is to ‘puddle’ it with your feet.

(or the feet of your family).While they were working the clay and sand together, I started on the sand former. My plinth is 1200mm wide, so the size of my oven needs to be 800mm in diameter (inside), to allow for the three 100mm layers of clay on the outside.

I marked out the oven with some string and chalk, then piled the sand on (about 8 bags). I used a stick with the height marked in tape (40cm) stuck in the middle as a guide.

Then I covered the sand with damp newspaper to stop the sand drying out while we applied the clay/sand mix. This is done by making clay ‘bricks’ — more like thick, short snakes. You start at the bottom and work round and round the former until you get to the top, punching the clay to make the joints as tight as possible.

Then I left it until the next day (about 20hours).

The moment of truth (well one of them anyway). The door should be around half the internal oven diameter wide by 63% of the internal oven height, high. For me this was 40cm x 25cm. I cut out the shape and then spent a nervous hour scooping out the sand (saved in bags for the final layer of clay render).

The dome kept it’s shape! So I lit a small fire inside and marvelled at my new oven!

This is where I got a bit carried away (and should have read more on how to dry out my clay oven). I kept the fire going all afternoon, and by the evening got cocky. I added in too much wood and the oven started to show cracks around the top.

Now, i’d read that cracks are normal, but it didn’t stop me stressing out about it. I slapped some clay mix on them and let the fire go out. The next day, the cracks weren’t that visible so I think I got away with it. We shall see.

Back to my rookie error. I made the oven with a non-heat bearing surface in front of the entrance. The plan was to lay 300mm square quarry tiles on this as a small work surface (suitable for tools etc). So far so good. Quarry tiles purchased, offered up and… Oh, the tiles sit above the hearth. This means that there’s be a lip down to the oven cooking surface. Now this may be ok, but frankly I think I’d end up regretting the mistake. My solution, cut out some of the concrete blocks in front of the hearth and use some smaller tiles to create a slope from the quarry tiles down into the oven. I think it looks ok.

Chimney, arch and insulation

Before going any further, I needed to create the door arch and chimney. This turned out to be way easier than I thought. I used a chunk of foam insulation to create a (wonky) arch former and then used the clay sand mix as a mortar to hold the bricks (Minecrafted from my garden again) in place. The chimney (a clay pipe from the salvage yard) balanced on the front of the dome and the top of two of the arch bricks (halved to create an opening) was also mortared in place with clay. The whole lot was surrounded by more clay mix.

Now I could apply the insulation layer. This is where thing get messy. I find that when clay water starts to fly, the number of keen volunteers seems to reduce proportionally. So when I spent an hour mixing lumps of clay with water in a bucket using a plaster mixer attachment on my drill, I did so alone. This clay slip (the consistency of yogurt) was then poured into a wheelbarrow containing two large bags of pet bedding wood chips, and mixed up like cheap granola. I was aiming for a mix that could be shaped and applied to the clay. Initially I worried it was to wet, but after couple of days in the sun, the newly applied insulation layer was pretty hard.

Before the final clay layer was applied I also cemented in some terracotta tiles round the edge of the plinth. The next layer would sit on top of the tiles making a nice seal (or at least that was the idea).

One week later, and we’re on the home stretch! This time I had no help with the clay puddling, so I’m not convinced I did a particularly thorough job. However, the resultant bricks made by myself and Laura (and stamped on from time to time by Toby) seemed to do the job.

Yes the arch is a bit wonky. Yes it has some ‘rustic’ elements (by rustic read: bodged), but by and large I’m happy with it as a first attempt.

It needs a week of drying (longer if this rain doesn’t let up!), a door, some tidying up… but it’s done! Hopefully the next pizza oven related post will be to show off the first cooking efforts!

Materials list:

40 concrete blocks £40
50 solid class b engineering bricks (for the hearth) £25
4 large terracotta tiles £14
2 lintels £18
Assorted minecrafted backyard bricks £0
25 small terracotta tiles £14
175 kg clay £87
14 bags of sharp sand £30
2 bags builders sand £4
1 bag of cement £6
2 large bags of pet bedding wood chip £10
2 tarps £8
1 plaster mixer drill attachment £10
2 stone cutting discs for my angle grinder £10
1 bucket £4
1 clay pipe £6

Total — £286