Introduction

A mudbrick oven looks like a beehive, a hemispherical cone, or the top of a giant's helmet partially buried in the ground. It cooks real food, that tastes wonderful. It can be a great communal attraction and you may never want to cook in a 'conventional' oven again.

Why?

Mudbrick is one of the most ancient building methods in the world. Ovens have been used for millenia and are one rung up from the open fire, in the culinary ladder of civilisation. Archaeologists have found the remains of mudbrick ovens from ancient Egypt, Persia and Mesopotamia. Most have been external structures, presumably due to the heat that the ovens produce and to the potential fire risk. They are more suited to warm or hot climates, which are conducive to al fresco cooking and eating, but mudbrick ovens can successfully used in a temperate climate.

Civilisation has moved on¹, so why bother with an ancient method of preparing food, when we have electric, gas and oil-powered ovens, which are indoors and out of the weather? Three reasons: there are millions who do not have power on tap, or socket; we may not have power on tap in a few decades² and some people aspire to a life of more adventure and greater simplicity.

Two key facts about mudbrick ovens should be borne in mind:

• A chimney is not needed. An oven without a chimney burns more slowly, giving the mass of the oven more time to absorb the heat of the fire.
• The oven is heated by a fire, not underneath the cooking space, but within it; and then raked out prior to use.

Who and Where?

Anybody can build a mudbrick oven. All the materials are free, except some concrete, so the only significant resource is time. Learning to build a mudbrick oven is an ideal introduction to general mudbrick construction and gaining experience of bricklaying and small dome building can lead to more elaborate and skilled construction.

The location of the mudbrick oven is worth spending some time over. It should be outdoors, a safe distance from any buildings or flammable fixtures³. For a single household, an oven with a diameter of about 1m is suitable, so an open area of 2sq.m is required: to allow for the base upon which the oven is constructed. The oven door should face slightly away from the prevailing wind, to allow some ventilation, but to reduce rain getting inside.

Construction

The Bricks

Make the mudbricks first, as they need to be completely dry before use. A framework measuring approximately 80mm x 20mm x 50mm made of wood offcuts is about the right size for the bricks⁴. Bigger bricks take longer to dry and will not go round the circle so easily. Mix mud with water to form a sticky slurry⁵. Place the framework on a large plastic sheet or board, undercover, and fill it with the mud slurry. Once it is packed, carefully lift the frame away and repeat the exercise, until there are about 200 bricks. Leave them to dry in a warm, dry and well-ventilated place for a few days. The bricks will crack slightly and they will not be uniform. This is normal.

The Base

While the mudbricks are drying, lay the base. This raises the oven off the ground, reducing the likelihood of damp and chef's backache. It can be as deep as necessary, but at least 80mm. Build a square wooden framework, about 2m across and fill it with cement. Before the cement completely dries, put a small wooden stake into the centre, and using a cord, mark off the perimeter of the oven: about 1m across.

The Walls

Spread a layer of damp mortar, 15mm deep, on the base where the first course of bricks will be laid. The mortar should be made up of the same mud and water mix as used for the bricks. Lay the first course on the damp mortar, as you would for any wall. The mortar between courses should be between 10mm and 20mm allowing for bumps in the bricks. Remember to leave a gap for the oven door - wide enough to get the biggest pizza through. Use a spirit level to check the bricks are all at the same height as the courses go up. Continue the brickwork, laying a maximum of 3 courses at a time and allowing the mortar to dry before laying the next courses. This prevents slumping. Point up and wash down each set of courses, inside and out, as soon as each set of 3 is completed. When the wall reaches a height of approximately 400mm the real fun starts - the dome.

But first.. The Doorway

The doorway will need a lintel, which can be made of concrete (and custom built once the dimensions are known) or metal⁶. The lintel can be placed in the curving section of dome wall if the door can be shaped accordingly. As a rule of thumb the doorway should be two-thirds the total height of the oven. The simplest door is one made of a thick hardwood offcut, cut to shape, with a wooden block handle bolted to it. It will last a surprisingly long time, as it will not be in place when the fire is burning.

The Dome

The simplest and most reliable method of dome construction is to use an internal frame, made of long flexible sheets of 3-ply or 2mm plastic. Place 6 to 8 of these with their feet inside the walls, so that they form a series of arches to create the dome shape. Bricks can then be laid in courses, as before, but following this shape. Lay one course at a time and allow the mortar to dry before the next one, as the potential for slumping and collapse becomes greater.

The mortar course for dome bricks must be thick on the outside edge and thin on the inside edge, to ensure the tilt of the brick. As the dome forms, each course becomes smaller and the size of the bricks needs to be reduced accordingly. Finish off the dome with a spiral pattern of the last few courses. Once the mortar is set, carefully remove the internal frame (cutting it out if necessary) and wash down the oven inside and out. Protect the oven from the weather until it is completely dry. If cracks appear⁷ fill them with mud mortar. The oven then needs to be mud plastered on the outside. Lay the plaster about 25mm thick onto the oven surface, which needs to be slightly damp for a good bond. If it cracks as it dries, give it a second coat of 10mm. To provide extra protection, coat the whole construction, including the base, with a thin layer of waterproofing material, such as cement. To finish the oven lay heat-proof tiles on the internal floor, upon which to cook the food.

Using the Oven

Heating the Oven

The first fire should be small and brief, to prevent cracking of the walls and to complete the drying process. After that, it is ready for use. To build and keep a good cooking fire, use the driest hardwoods. Do not use firelighters, as they will fill the oven with fumes, so keep a stock of dry kindling to hand. Do not use any pressure-treated, tarred or creosoted wood, for the same reason. Light a fire inside the oven, to heat it to the required temperature. This should take about an hour. Leave the door off, to allow ventilation and greater heat generation. Use a thermometor to measure the temperature of the oven, or throw a few wheat grains onto the floor of the oven (not onto the fire). If they burst, it's about right for pizza cooking.

Cooking

When the oven is hot enough, rake out the fire and ash. Place the item to be cooked inside. The food can be placed directly onto the oven floor, in a clay pot, or on a pre-heated flat stone. Close the door and seal it with mud, if the cooking is a long process. There are no exact cooking times: it takes as long as it takes. It is efficient to put as much as possible into the oven at once. The more is cooked, the more of the stored heat is used. Pizzas and other quick hot cooking should be done first, followed by bread and meat roasts, then casseroles and other slow cooked food. There should be sufficient heat stored in the walls and floor of the oven to cook for up to 2 hours. If it cools too much, simply remove the food, replace the fire until it is hot enough again and carry on cooking.

That's It!

It is as easy as that. Building a mudbrick oven takes mostly natural materials, some forward planning, some mudbricks and quite a lot of labour. For all that, there is immense satisfaction when it's first fired up. As for cooking: that is a great gourmet adventure and you will never eat a better pizza.

Bibliography

• "Building a mudbrick beehive oven" Bakes, R. Earthgarden Magazine No. 88

• Building a Horno: the Adobe Bread oven Moquin, M.

• Oven Building

• Building and Using a Medieval Style Hemispherical Bake Oven