Cordwood construction looks somewhat like a stack of firewood. This method building method is charmingly rustic, but also results in a highly insulated and energy efficient structure. This natural building technique has been around for 1,000 years, and may be used for new homes, additions and outbuildings.
How It Works
Short pieces of wood, typically from fast-growing species like poplars and cedar, are stacked and held together by mortar. The flat ends of the wood create the interior and exterior surfaces of the wall. Their length determines the wall's thickness, along with an insulated cavity in the middle that is typically filled with sawdust. In total, cordwood walls typically range between 12 and 24 inches deep. It is possible to admit natural light by using bottle ends in place of some pieces of wood.
Benefits to Cordwood Construction
Building with cordwood offers several benefits to the homeowner:
- Walls are dimensionally stable, with little expansion or contraction.
- The thickness of the wall creates a thermal mass.
- It provides a use for waste wood that would otherwise end up in the landfill, such as pieces that are unsuitable for firewood.
- Cordwood is affordable. In many cases, you can obtain free scrap-wood from sawmills, log cabin builders, or furniture makers.
- Using local building materials cuts down on fossil fuel use for transportation.
- Many homeowners can do the work themselves-all you need to do is be able to mix mortar and use tools to cut the logs, such as a buzzsaw or chainsaw.
- Since natural materials are used, there is no off-gassing, only a pleasant woodsy smell.
- Cordwood can be constructed in curves as well as straight walls.
- It is low maintenance, and no other materials are required to finish the exterior or interior surfaces.
- The result is in a long-lasting structure that biodegrades better than most construction types.
There are always a few drawbacks to every construction type, and cordwood is no exception:
- Though cordwood construction exhibits good compression strength, it typically functions best as infill within a post-and-beam structure.
- Wood should be debarked before use, and it should ideally be dried for a year before construction begins, so you must plan ahead.
- The aesthetic is not for everyone, and if you aren't a fan of the rustic look, cordwood might not be a good fit for your home.
- This type of wall construction does not admit a lot of natural light, and it can be challenging to incorporate electrical wires and plumbing pipes.
- The cement used for the mortar isn't so green, but it you don't need to use a lot of it and there are some alternatives that are more eco-friendly, such as lime putty mortar and cob (clay, sand and straw mixture).
- Cordwood walls are heavy, so you must verify that the soil and foundation can support it.
- Since wood is prone to fungi growth, cordwood walls must be protected from the ground with a masonry base and from the rain by an overhang that is at least 12 to 16 inches deep, so that they don't absorb moisture.