Cordwood
Cordwood construction is a building technique where short logs are laid crosswise in a wall and supported by a mortar mixture.
This versatile technique is suitable for both interior and exterior walls and is often used as a decorative element in restaurants and bars. In regions with low seismic activity, cordwood walls can serve as load-bearing elements, but they are more commonly used as non-load-bearing walls in combination with a post-and-beam construction.
A Look into History
Cordwood houses can be found worldwide, from America through Europe to Asia. In the USA, there are houses over 100 years old that are still in excellent condition today. In Germany, remains of cordwood structures have even been discovered that are up to 1000 years old. Nevertheless, little is known about the origin and historical development of cordwood houses.
The Material
Cordwood construction is based on two main components: wood and mortar. For the walls, lighter, less dense woods are preferred as they are less prone to expansion and shrinkage and offer better insulation values. The wood must be as dry as possible, and the bark should be removed to prevent rot and insect infestation. Cedar and pine are particularly recommended, but other softwoods are also suitable. In total, more than 30 different types of wood can be used, with local woods being preferred for sustainability reasons.
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The mortar can be made in various ways:
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Cement mortar: traditional mixture of cement, lime, sand, and sawdust
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Lime mortar: lime putty (lime, sand, possibly cellulose) or hemp-lime mortar (hemp, lime, sand)
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Clay mortar: cob mixture of sand, clay, and straw
Building Method and Application
The construction involves several steps:
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Determining the wall thickness (typically 40 cm)
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Applying a 10 cm thick layer of mortar on both sides
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Embedding the logs through the entire wall thickness
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Filling the spaces with insulation material (sawdust, straw-clay mixture, or sheep's wool)
​Cordwood walls can be built using two different methods. In the classic variant, the logs are embedded directly into a solid wall, with the spaces between the logs filled with mortar. A modern alternative is the double-wall method, where two thinner cordwood walls are erected parallel to each other. The resulting cavity between the walls is filled with insulation material, which significantly improves the insulation properties.