1. Building a Clay Oven – The Basics

[PLEASE NOTE THAT THE LINKS TO THE OTHER 7 PARTS OF THIS ‘HOW TO’ CAN BE FOUND ON THE LEFT HAND COLUMN. ALTERNATIVELY JUST CLICK THE LINK AT THE BOTTOM OF EACH SECTION TO GO TO THE NEXT PART]

Welcome to the first installment of building a clay oven.  This post will cover:

1. Background – including what is a clay oven?, what can you use it for? can I build a clay oven?
2. What you will need – Materials and equipment
3. The build order
4. How long it will take to build
5. How long will it last?

Background

The Finished Clay Oven in My Garden

I assume that most people who have found this site will already know what a clay oven is, however it is probably useful if I define what I mean by a clay oven for the purpose of this blog.  Before I do that though a quick word about nomenclature.  I will use various names for the clay oven interchangeably, these include “clay oven”, “traditional clay oven”, “wood fired oven”, “pizza oven” and “traditional bread oven”.  If you browse around the web you will also see the name “cob oven” being used – cob being a mixture of clay and straw (+ or – sand).  As I am not using straw in my build I will not use the term cob but will include it in my definition as this type of construction is probably the most ancient of all clay ovens.  Another name commonly used is earth oven.

In my definition then, a clay oven is any hollow, dome-shaped structure constructed out of clay, clay and sand or clay and straw, used for the purpose of baking and roasting food.  It has a brick floor and usually a chimney.  Most traditional clay ovens are built outdoors and may or may not be covered with a simple roof structure.  You will find some amazing examples of clay ovens, particularly huge pizza and bread ovens, built inside restaurants.  The oven I have built is much smaller but still suitable for cooking for large groups of people.

Clay ovens are amazing things.  They look incredible and create a feature in any garden, large or small.  The most important reason for having a clay oven for me though is for cooking.  If you have never eaten a pizza cooked at 450°C for 1 minute in a clay oven – you have never eaten a pizza!  Just imagine a thin, crispy, slightly charred base covered in hot melted cheese, olive oil, garlic, sun-dried tomatoes, dried cured sausage, smoked ham, anchovies…do I need to continue?  How about loaves of hot bread cooked to perfection, cracked open and smothered in real dairy butter or a large joint of lamb or pork belly cooked slowly with herbs over night in the oven’s residual heat, falling off the bone when you come to carve it the next day.  OK OK enough of the M&S style adverts already!  I think you get the picture.  Cooking in a traditional clay oven is wonderful, it feels different and definitely tastes different.

Building your own clay oven is not difficult.  I am by no means an expert when it comes to DIY but am normally happy to give things a go.  I have never built anything like this before but managed to complete my oven without any major disasters.  The beauty of building a clay oven is that you use mostly natural and, if you are lucky, recycled or free materials.  There is something very primeval about building one of these ovens.  The process is a direct link back to our ancestors who would have used similar techniques for cooking many millennia ago.  I thoroughly enjoyed building it! It is a very physical and tactile experience – you will handle and form every single piece of clay, sand and wood that goes into it and the finished product is something that you will be extremely proud of.

What you will need – Materials and equipment

OK lets crack on with getting this baby built!  Here I will list most of the equipment and materials you are going to need to build your own clay oven.  I will provide details such as quantities later on as I step through the build process.

Materials

• Builders sand
• Clay
• Water
• Rubble / hardcore
• Wood shavings
• Normal building bricks (e.g. London Bricks) for oven base
• Large wooden “beams” or bricks or stone for plinth (I used beams as you will see later)
• 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
• Wood for burning in the oven

Equipment

• Saw (chainsaw?)
• Wheelbarrow
• Bucket
• Tarpaulin or thick plastic sheeting
• Shovel
• Spirit level
• Large knife
• Hands and feet!
• Wellington boots or other sturdy boots

The Build Order

So you have your equipment and materials list.  Next I thought it would be useful to outline the order of construction.  This will also form the basis for the rest of the posts in this series, each post providing details for each stage in the build process.  Simple – I hope!  As you might have guessed already, I love a good list so here goes another:

1. The plinth foundation, plinth and brick oven floor
2. The clay-sand mixture and puddling technique
3. The dome sand-former and first layer or the oven layer
4. The oven entrance and chimney
5. The wood shavings and clay slip layer or the insulation layer
6. The final clay-sand layer
7. Firing the clay oven
8. Cooking in the clay oven

How Long Does it Take to Build a Clay Oven?

Construction involves quite a few steps and each step takes variable amounts of time to complete.  Probably one of the most time consuming processes is puddling (mixing with your feet!) the clay-sand mixture.  One batch (two buckets of sand to one bucket of clay) will take about an hour to an hour and a half depending on the consistency of the component parts.  If you get a group of people to help then obviously you can speed the process up.  Many feet make light work of puddling!  Building the oven layers is also very time consuming and you need to leave drying time between each layer if possible.  The other major factor which effect the length of time it takes to build your oven is the weather.  You can’t construct anything other than the plinth if it is raining and it does tend to rain quite regularly in the UK!

What with interuptions (both weather and non-weather related) from start to finish my oven took 6 weeks to build on my own.  However if you have a spell of good weather and a few helping hands (and feet) I think you could build one in a week.

How Long will a Clay Oven Last?

To be totally honest I have no idea how long it will last.  I have only had mine in my garden for a few weeks now.  The good people at River Cottage HQ suggest a couple of years but obviously this will vary by your location, local temperatures, weather conditions, air moisture content, the type of cover or shelter your oven is housed in, the amount of use your oven gets, the type of clay you use for construction and many other factors.  They are pretty robust but they are organic structures and they do crack after repeated heating and cooling.  This is not a problem if cracking only effects the outer layer – you can fill the cracks with spare clay-sand mixture.  However, once you get cracks in the internal oven layer then the oven’s days are numbered.  I say, don’t worry too much, enjoy it and use it and if it falls apart you can build another one!