Building a Medieval Clay Oven in the Anglo-Saxon House - Part I | Romano-British Updraft Furnace 

The Anglo-Saxons and Romano-British built clay ovens to cook food, bake bread, and heat their homes.
These ovens were built of cob; a mix of clay soil, sand, gravel and straw.
While gathering resources for the oven I also finished the interior walls of the pit house. The wattle walls were covered with a daub of sandy clay and straw. This was then covered with lime wash, mixed from slaked lime. The walls were painted with two coats, but will need several more over time.
Gathering cob materials is hard, heavy work, and one of the buckets broke free of its hazel hoop, so another was quickly fashioned to repair the bucket.
This oven design is based on an updraft kiln used by both the Romano-British and Anglo-Saxons. Early Anglo-Saxon examples have been found at Cassington, Oxfordshire. In these kilns, the fire is stoked from below, and is drawn up vertically through a flue or vent into a clay or turf dome above, with a smoke vent in the top or side of the dome.
These updraft kilns were primarily used for pottery, and there is no evidence that they were used indoors or for cooking. However, I wanted to create a design that aligned with the known technologies of the time, but allowed for a smoke free house!
First, a small chimney and arched stokehole were built as the 'updraft' part of the oven. This is known in modern times as a 'rocket stove'. This chimney was built up around into a solid cob block, to provide good thermal mass for heating the house.
Heavily grogged cob, with lots of gravel for thermal resistance, was used for all areas in direct contact with fire, while the rest of the block was made of standard straw cob. The arch and chimney were supported temporarily by hazel frames until dry. These will frames will eventually burn away as the oven is used.
The domed oven was built around a woven willow frame. Again, this frame will burn away eventually, leaving the solid cob dome. A thermal layer was applied first, followed by a straw cob insulation layer.
An outlet flue was formed from the back of the dome, out through a hole in the wall, to the exterior of the house, which will allow the smoke to exit.
The floor was covered with dry rushes for warmth, and a test fire lit in the oven, to check it worked as intended. The updraft draws the fire well once it is going, with little smoke, and once a door is added to the upper entrance of the oven, there will be very little, if any, smoke in the inside of the house.
Next, the oven just needs a cob door, flue grate and some finishing touches, before it is ready to start experimenting with baking!
With thanks to:
Herknungr, Musician, playing “Spekð".
Grzegorz Kulig, Silversmith, for making the pattern-welded knife.
Matuls, Cooper, for making the alder bucket with hazel rings.
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