Positioning and building the base of a bread oven
This is part 2 of How to build a free-form bread oven. Click here for bread oven principles, plans and construction recipes (part 1), how to build the oven floor (part 3), how to build the bread-oven dome (part 4), the final layers (part 5), make your own oven tools (part 6) or cooking in a bread oven (part 7).
Where to position a wood-fired oven in the garden
Face the door of the oven side-on to, or facing, the prevailing wind. Even if
there is only a zephyr wind, it is better that any smoke that develops as you
are lighting the oven blows away rather than into your face. Once the oven is
hot there will be virtually no smoke, but it is better that any smoke coming
from the chimney stack blows away from the cooks and the guests. Also beware of placing the oven close to a building with a sloping roof. If wind is likely to
come down the roof line it may push smoke from the chimney back down the chimney or on to guests. If you have a bank in your garden where you could build the oven at waist height and stand on the ground below the bank to service it,
you’re home laughing! You don’t have to build a base. But the retaining wall for
the bank must be strong if you want your oven to be there a long time.
Building the base
The base of a wood-fired oven can be made from almost anything, but it must
be sturdy because the structure of the oven itself is very heavy. Many people
build the base from concrete building blocks. Others use a steel frame.
I built the base for my oven with river stones (photo above right). In the centre is an old concrete incinerator which gives vertical strength in the middle that the weight of the oven sits on. (A tower of building blocks in the centre could take the place of my incinerator.) The rocks in the round rock wall are held together with a mortar of 1 part cement to 3 parts sand. The wall must be built up gradually all round. I placed a full circle of rocks that fitted well and balanced well on their own before I applied the mortar. Once the rocks were balanced well I lifted each individually, applied mortar and then settled the rock into place. This took several days as I built only two layers at a time so that the weight of rocks did not distort the balance or mortar. As the walls rose, I filled any gaps between the rock wall and the central incinerator with scoria. On the top I laid a slab of concrete 750 mm (3 inches) thick, reinforced with steel reinforcing rods. The concrete mix was 1 part cement to 2 parts sand and 3 parts gravel. Use rubber gloves to protect your hands from cement burns. Leave the surface of the concrete rough so that the next layers will adhere readily.
What size should the base be?
The base must be at least the diameter of the oven plus the insulating layer
and refractory layer. See the plan on page 1 here. Also allow more room in the front for the doorway. My base is more egg-shaped than round, by the time it reaches the concrete slab layer, to allow for the door tunnel slab. It was at this stage that the paper real-size plan came in very handy, rather than constantly
struggling with a ruler or tape (see Planning the oven). The top of the completed
concrete slab is about 800 mm above the ground.
Some people like to make the base a lot wider so that the base also forms a
workbench alongside the oven. My preference was to keep the oven free-standing
and the workbench a metre-or-so away because there is always more than one
person wanting to have a go at the cooking. Also, the long handle of the paddle
tool for putting items in and out of the oven needs a lot of arm room!
To learn how to Build the oven floor, click here.