Everything you need to build your own traditional pizza oven

IMG_0899In my book I outline the steps one should follow to build a traditional pizza oven. As a result of following these instructions, lots of people all over the world have now built their own ovens. One question I still get asked quite often is how much x do I need (where x can be clay, sand, bricks etc.). To be fair, I didn’t include lots of quantity details in the original book (new edition coming soon) because, to be totally honest, I didn’t record this information during my first build.

Anyway, at a recent build I made sure I took note of everything we used, and so here are those all important quantities and a full list of other equipment required.

NOTE: 1 bag of builders sand (approx. 15kg) fills a 15 litre bucket. 

RATIOS

Normally I prescribe a  2:1 ratio of sand to clay but this is a rule of thumb. You need to aim for a mixed material which holds firm, is not too soft (or wet) and not too dry. If it is too wet (or if there is too much clay) it will slump around the base of the layer you are building.

In the quantities outlined below I use a ratio of 2:1.5 for the first and outer layers, and a softer, clay-rich ratio mix of 1:1 for building the brick arch, the backfill and chimney, mainly because it is manipulate.
Clearly the plasticity of the mix will depend upon the moisture content of the clay and the sand you are using. The drop test* will help. I’d always err on the dry side, you can always add a little water (or more clay) if you need to.

SAND – 18 bags (approx. 270 kg)

  • 10 for the dome former
  • 4 for the first (oven) layer
  • 2 for the brick arch, backfill and chimney
  • 2 for the brick arch former
  • 7 for the final layer (you will use the sand excavated from the dome and arch formers for this final layer which means you’ll have approx. five bags leftover at the end)

CLAY – 12.5 buckets (approx. 190 kg)

  • 3 for the first (oven) layer
  • 2 for the brick arch, backfill and chimney
  • 3 for the insulation layer
  • 4.5 for the final layer

OTHER MATERIALS AND EQUPIMENT

  • 2 large bags of wood shavings
  • 36 London bricks (11 for the arch, 25 for the oven floor)
  • Water
  • Rubble / hardcore (for the plinth fill)
  • Large wooden “beams”, sleepers, logs or bricks for the plinth (this depends on how you decide to build it)
  • Cement if you are building plinth out of brick
  • Right-angled brackets and screws if constructing plinth from wood
  • Glass bottles (optional)
  • Old newspapers
  • Plastic rubble sacks
  • A bucket or two
  • A drill with plaster mixer (optional)
  • A knife

*Drop Test – Form a tennis ball sized clay:sand ball in your hands. Drop the ball onto the ground from shoulder height. If the ball explodes, the mixture is too dry, if it “splats” it is too wet. Ideally the ball should just hold together.

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3. The Clay-Sand Mixture and Puddling Technique

So now the fun begins!  Before I get on to detailed instructions of how to build the oven I want to provide some details on preparing the all important building material – the sand-clay mixture.

Ingredients

  • Builders sand
  • Clay
  • Water (optional)

Equipment

  • Shovel
  • Bucket
  • Tarpaulin
  • Thick plastic bags
  • Wheelbarrow
  • Wellington or other sturdy boots
  • Legs!

You can buy builders sand from any building suppliers, some garden centres and DIY stores (e.g. B&Q). Either buy it in individual plastic bags or get a job-lot delivered – you will use quite a lot.  

What type of clay should I use?

I have had quite a few questions about the type of clay to use.  As far as I know you can use any type of clay you can get your hands on.  I dug my clay from a local farmer’s field here in Hampshire (clay overlying Upper Cretaceous chalk if you are geologically minded – maybe Paleogene?).  The team at River Cottage get theirs from a pond on site, in Dorset (I think it is Blue Lias).  If you can’t find any clay locally you could always buy potters clay which would be wonderfully homogeneous – free from large particulate matter.  Which reminds me, try to get clay does not contain too many stones – they are liable to form the focus of cracks in your oven if left in the mixture.  

Quantities

The ratio of clay to sand is 1:2 (one part clay to two parts sand).  I used a bucket as a convenient measure and found that one bag of builders sand almost filled two buckets which was nice!  

I think it is wise to make-up just enough mixture (with a little bit extra) to complete one layer of your oven at a time.  Why?  Well if you make up a huge batch (enough to complete your oven) it could dry out before you get a chance to use it if you get delays between layers (if it rains for example).  So how much do you need for one layer?  This will vary depending on the size of your oven.  For mine, if we define one “batch” as two buckets of sand mixed with one bucket of clay, the first (oven) layer took three batches (6 sand to 3 clay).  This left enough over to fill small cracks after drying and to begin building the chimney.  The outer layer required more mixture because it is covered a larger surface area.  I used four and a half batches for this layer.

Mixing or Puddling

Clay chunks distributed onto sand ready for puddling.

Clay chunks distributed onto sand ready for puddling.

Mixing the clay and sand is by far the most tedious part of the whole build process.  What you are trying to achieve is a well-mixed material with no pockets of unmixed sand or clay and the only way to do this seems to be by using your feet.  The process is known as puddling and it goes like this:

 

  1. Spread a tarpaulin out on a firm surface (double it over in case you get holes in it).  
  2. Tip two buckets of sand in a pile onto the tarpaulin and spread out a little.  
  3. Next, fill another bucket with clay.
  4. Take a chunk of clay and break it into small pieces (thumb sized) and distribute them over the surface of the sand (like throwing broken-up pieces of mozzarella onto a pizza base!).  Take this opportunity to dispose of any stones or sticks you might find in the clay.
  5. Puddling Sand-Clay mixture with help from my dog Scout!

    Puddling Sand-Clay mixture with help from my dog Scout!

    Wearing your boots, start to mix the sand using your feet (puddling).  The best technique is to tread and twist.  I recommend putting some music on and get into the groove! Seriously, you will look pretty daft doing this but you need to twist – Chubby Checker sty-lee!  This is where a group of friends come in very handy.  Many feet make light work of puddling sand and clay.  It is great exercise though so keep reminding yourself how much good it is doing you when you start to get knackered and bored!

  6. Keep mixing until the clay lumps have disappeared then add more clay chunks and get back to puddling.
  7. Keep repeating this until the bucket of the clay is mixed into the sand.

I found it takes somewhere between 45 minutes to 1 hour to mix one batch.  One tip I discovered which speeds things up is make sure the sand is damp before you start mixing.  It definitely helps the clay mix in better (essentially you are coating sand grains with clay and water helps break down the clay bonds I assume?).  Add some water before hand if you need to but dont go mad with it!

The last thing you need to do is check that the mixture is of the correct consistency i.e. not to wet and not too dry.  You might be surprised at how sandy the mixture seems but this is how it is meant to be.  The team at River Cottage HQ had a great method for testing the consistency though which I will share with you.  

  1. Sand - clay ball after drop test.  It held together just right!

    Sand - clay ball after drop test. It held together just right!

    Grab a handful of mixture and form a ball about the size of a lime.  

  2. Hold your arm directly out in front of your body at shoulder height.  
  3. Drop the clay-sand ball onto hard ground in front of you.

The ball should hold together quite coherently.  If it splats flat the mixture is too wet and you should add more sand to dry it out a little.  If the ball breaks to pieces (explodes) it is too dry and you can add a little water.  Simple!

Once you are happy that your mixture is just right shovel it into a thick plastic bag to keep it moist while you mix the next batch.

If you are ready to start building your first layer I recommend shoveling the final batch into a wheelbarrow for ease of use.  Wheel it over to your plinth – it’s time to start building your oven!