Roof Cob Oven

About 2 parts sand to 1 part clay.

Roof cob oven. You would place a bond beam at the top of the cob wall ideally concrete and rebar or alternatively airplane cable connecting all the members of the roof in one big circle. For the uninitiated cob is a combination of clay sand straw and water. Any smaller and you won t have good heating or a large enough cooking surface. Materials are raw and often sourced locally from the land.

They way the roof is designed is to act in compression while exerting force on the bond beam which will act in tension. However i wouldn t recommend either of them for an oven. Dampness isn t a problem but exposure to driving rain or even steady dripping will quickly erode cob. When dry cob is extremely hard and durable and highly capable of storing heat given enough insulation the focus here is of course building with natural and recycled materials whenever possible.

The smallest cob oven interior size that we ve heard of is 16 floor diameter. You mix those two together so that they re very well mixed. Pour off the water from 3 buckets of clay and dump the clay into the sand pile. When you bake something like bread in an oven it releases an enormous amount of water vapor as it cooks much of which is absorbed into the oven wall.

Use your hands to carve out a small depression in the middle of the sand pile. The inner most layer of mud or cob that we re going to put on our oven is just sand and clay. I m not in the construction trades. Linseed oil and lime plaster are both sometimes used to seal cob against weather.

Lime wash creates a somewhat weather resistant surface but doesn t fully replace a roof. The oven i will propose and outline below is a highly insulated cob oven. Cob ovens are a relatively inexpensive way to bake with all the benefits of wood fire such as a hot hearth. The interior ceiling height should be around 75 of the interior oven floor s diameter and the door height should be about 63 of the ceiling height.

The oven is a design from build your own earth oven by kuko denzer. Sand about 30 40 gallons to fill oven s base and to put in cob as needed sand can often be found by bodies of water or collected from construction sites like subsoil. This cob oven was built leading up to the 2008 forest festival held in jackeys marsh tasmania. Straw one bale to make cob make sure you do not confuse straw with hay.