Cob: A Sustainable Building Material
Cob is an ancient building material that combines water, clay soil, silt, coarse sand, and fibrous organic matter (such as straw). When mixed together, it forms a stiff mud that can be shaped into walls while wet. Here are some key points about cob:

Natural and Environmentally Friendly: Cob is sustainable and eco-friendly. It doesn’t involve industrial processes or energy-intensive production.
Thermal Mass Properties: Cob has excellent thermal mass properties. It can absorb and store heat, releasing it slowly over time.
Versatility: Cob can be used for walls, floors, and even sculptural elements in buildings.
Local Sourcing: Since cob is made from soil sourced on-site, it reduces the need for transportation and minimizes carbon emissions.
Cob as Thermal Storage Around a Wood Burner
When you build a wall around a wood burner using cob, you create a thermal mass that serves several purposes:

Heat Absorption: The cob wall absorbs the intense heat generated by the wood burner during operation.
Heat Retention: Once heated, the cob retains this warmth and gradually releases it into the room, even after the fire has died down.
Improved Efficiency: By placing cob around the wood burner, you enhance its efficiency. The stored heat continues to warm the space, reducing the need for constant burning.
Considerations:
Safety: Ensure that the cob doesn’t interfere with the wood burner’s intake or components. Safety is paramount.
Initial Impact: Initially, the cob may absorb some of the stove’s heat, affecting its efficiency. However, once the cob warms up, it will enhance overall performance.
Monolithic Mass: The cob mass should be monolithic (without air gaps) to maximize its thermal properties.