How to Make a Wood-fired Clay Oven

Summers now at its peak and everyone is drawn to the back garden to soak up the rays during those long sunny days. What better way to enjoy some real alfresco dining than with your own homemade rustic food in your own homemade wood-fired clay oven. A great way to impress the guests and a great way to cook authentic meals simply without having to leave your guests to fumble around in the kitchen. Also check out the best wood-fired oven pizza recipes.

Here is a simple guide on how to make a wood-fired clay oven in your own back garden, using simple everyday items from your local DIY store, building merchants or from free recycled materials. Try freecycle.com, preloved.com, EBay, gumtree.com, the recycling centre or local sales pages on Facebook. If you can do basic DIY you can create this impressive work of art right in your own back garden.

It is worth noting that clay ovens take an hour to get up the temperature, but once it does you can cook authentic meals such as pizza in as little as 60 seconds, which comes out with a crisp base and delicious smoked flavour. Wood-fired ovens cook at a very high temperature around 400C, whereas household ovens cannot get this high. Once cooled to around 130C it is perfect for slow-roasting joints throughout the day or overnight.

Plan
Plan where to position your oven. Unlike a barbeque, you can’t move a clay oven around once it’s build. Choose a site with lots of space around it and ideally somewhere in full sunlight. You should be able to make it over a sunny weekend depending on the weather.

Materials
• About 30 bricks: at least 20 will need to be smooth and solid, with no recess (frog) or holes (perforations), to form your oven floor.
• 20 breeze blocks and 5kg tub of cement or twenty 120cm x 20cm x 20cm wooden beams, an electric drill and long wood screws (for the plinth frame)
• Rubble and big stones
• 10-14 bags of builder’s sand (20kg each)
• 125-175kg clay (the cheapest will do – try angliaclaysupplies.co.uk)
• Assorted glass bottles
• Chimney or plant pot (optional)
• Large bag (14 litres or 6kg) of wood shavings (from pet shops)

Equipment
• Wheelbarrow
• Tape measure
• Large heavy-duty plastic or tarpaulin sheet
• Plenty of water
• Old kitchen knife
• Heavy duty gloves
• 10-litre builder’s plastic bucket
• Wellington boots
• Lots of newspaper

Technique – Puddling
• Mixing the clay and sand is the hardest, most time- consuming part of the building process. It’s best to mix this in batches as and when you need it.
• For the first layer (step 3) you’ll need about three buckets of clay to six 10 litre buckets of sand. The final shell (step 7) will need four buckets of clay to eight of sand (1:2 ratio clay: sand).
• You do the mixing (puddling) with your feet. Tip the sand onto a large plastic tarpaulin sheet, break the clay into thumb-size pieces and, wearing wellies, tread the two together with a little water. This is called puddling. The mixture is ready when a tennis ball-size piece dropped from shoulder height holds together. If it splats, the mix is too wet; if it cracks, it’s too dry.

Method
Step 1: Make the plinth
(Takes about 4 hours)
This is the foundation of your oven, so it needs to be solid. You can build the plinth frame out of bricks, breeze blocks or wooden sleepers. Clear the ground and dig a shallow trench 120cm x 120cm square. If you build the frame from bricks or breeze blocks, use cement. If you’re using wood, screw the pieces together. You’re after a solid, square box approximately 1m high and 120cm square.

Put a layer of rubble and stones in the centre, then add a layer of sand and glass bottles. These will act as a heat sink, warming up, then radiating heat back up through the oven. Finally, top with a layer of smooth, solid bricks (1b) to form the oven floor. Bear in mind this is the surface you’ll cook on, so the bricks need to fit snugly together.

Step 2: Make the dome mould
(Takes about 1 hour)
Make a mound of damp sand to form the clay around. You’ll need about 120kg sand. Centre it on the plinth you’ve already built and gradually construct the dome up like a giant sand castle. It needs to be 80cm in diameter at the bottom and 40-45cm high. Keep checking on it from above to make sure it’s round. When it’s finished, cover with wet newspaper to stop it drying out while you puddle the clay.

Step 3: The first oven layer
(Takes about 2 hours, plus 4 hours drying)
Roll handfuls of the puddled clay/sand mix into 20cm long, 10cm thick sausage shapes, then build them up in circles around the sand dome, starting from the base (leave the newspaper on), until the dome is completely covered. Work the clay lengths into each other, then smooth the outside with your hands. The layer should be about 7-10cm thick. Leave the clay to dry for 4 hours.

Step 4: Cut the entrance
(Takes about 1 hour)
Using a kitchen knife, cut out the entrance to your oven. It needs to be big enough to fit a roasting tray through it, but small enough to keep the heat in – about 30cm wide by 20cm high. Once you’ve cut the entrance, scoop out the sand inside (you can reuse it). Let the dome dry overnight. The next morning, light a small fire inside to help dry out the clay further.
(Takes 2-3 hours)
Build an arch to fit around the entrance using bricks and more sand/clay mix as mortar and to create the angle for the arch. Secure the arch to the clay dome with more clay mix. Next, cut a hole in the roof of the dome near where the arch joins the dome and build a clay collar to hold the chimney. You can use a plant pot as a chimney, buy one, or build up rings of clay to make one (as in the photo).

Step 6: The insulation layer
(Takes about 1 hour, plus 2 hours drying)
Make 4 litres of slip (a mixture of clay and water with the consistency of cream). Stir in 14 litres/6kg wood shavings until well mixed. Slap the insulation layer onto the clay dome, then leave to dry for 2 hours.

Step 7: The final shell
(Takes about 2 hours)
This is the same as the first oven layer, just slightly larger. Mix the clay and sand together by puddling. Make sausage-shape bricks and press firmly together to cover the insulation layer until 7-10cm thick all over. Smooth the surface as in step 3. Once the finished oven has had a chance to dry out for a day or two (a week would be even better), clean out any remaining sand or debris… And you’re ready to fire it up!

How to Use Your Wood-fired Oven
You ideally need properly dried hardwood to cook with a light pile of newspaper and small sticks of soft dry wood in the entrance, below the chimney. Slowly build the fire in the same way as wood burning fire by adding pieces of hardwood, then once going, slowly push it to the back of the oven. Once roaring, add enough wood to just keep it going.

Oven Care & Maintenance
When not in use, protect the oven from damp with a well-secured tarpaulin.

There are quite a few of Build and Bake courses available around the country to make your own wood fired ovens and dishes to cook in it. A couple of the top courses available include Sustainability Centre in Hampshire or River Cottage in Devon. Manna from Devon also offers courses on how to get the best out of your wood fired ovens and the best recipes to cook in them.

Once build this is a simple yet effective alternative to a BBQ to delight your guests with. If you want to create authentic food with a delicious smoky flavour that cannot be achieved on the BBQ or in a standard kitchen oven, then this is the way to go. Now you’ve created your masterpiece why not celebrate with a wood-fired oven pizza party! Check out the Ultimate Wood-fired Pizza.