Quick Answer
Cordwood construction has several advantages over cob construction, including higher thermal mass, improved durability, and increased structural integrity. Cordwood walls can retain heat better due to their density and the use of insulation. Additionally, cordwood masonry can be built to withstand harsh weather conditions.
Higher Thermal Mass and Insulation
Cordwood walls achieve higher thermal mass due to the density of the wood and the insulation provided by the cordwood mixture. This mixture typically consists of 50-60% wood, 20-30% insulation material (such as sawdust or wood chips), and 10-20% lime mortar. The high thermal mass of cordwood walls allows them to absorb and release heat slowly, reducing temperature fluctuations and energy consumption.
Improved Durability and Structural Integrity
Cordwood masonry is more durable than cob construction due to the use of wood, which provides a higher compressive strength. The addition of lime mortar and insulation materials also enhances the structural integrity of cordwood walls, making them better equipped to withstand external forces and weather conditions. A typical cordwood wall can be designed to withstand wind loads of up to 100 mph (160 km/h) and snow loads of up to 50 lbs/ft² (240 kg/m²).
Log End Walls and Mortar Mix
Cordwood construction often employs log end walls, where the logs are stacked on top of each other to form a wall. This technique allows for a higher degree of thermal mass and structural integrity. To achieve a strong bond between logs, a high-strength lime mortar mix can be used. A typical mortar mix consists of 1 part lime to 2 parts sand, with a water-to-mix ratio of 0.5. This mixture provides a strong and durable bond between the logs, ensuring the stability of the cordwood wall.
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