One reason why cordwood homes are a good choice for green builders is how long they last. In Siberia and northern Greece, cordwood structures estimated to be a thousand years old still stand, but no one knows where cordwood building began. In the United States in Wisconsin, there is a cedar cordwood house in Old World Wisconsin village, made by Polish immigrants in the 1880's, with a cordwood chicken coop built into the side of the house.
The pros for cordwood:
- If you already have a large supply of firewood, your wall-building material is just sitting there waiting, so it is easily accessible.
- Cordwood is inexpensive.
- Cordwood provides a good thermal mass and decent insulation. A sixteen-inch-wide wall will have about a 20-25 R value.
- Cordwood is a renewable resource.
- Cordwood is low impact on the environment and obviously durable.
- Cordwood can be cut to different sizes for thicker walls and greater insulation.
- No interior or exterior finish is needed over the cordwood.
- You can build any shape with cordwood.
- Even a novice can build cordwood walls, so you can save a lot of money on labor costs if you build it yourself.
- Cordwood is beautiful; very esthetically pleasing.
- Only the cordwood goes all the way through the wall. The mortar is about four inches on the inside and outside, but the gap in the middle is filled with an insulation like sawdust.
- Cordwood homes have high fire resistance. The 1994 Continental Cordwood Conference papers, available from Earthwood, have an article on fires in cordwood, citing a fire that occurred when a propane-fired freezer exploded. The house did burn after two days. After the insurance company witnessed this, they dropped their insurance rates on cordwood homes, finding them far superior to conventional stick frame houses.
- Cordwood is hygroscopic, taking in and giving off water vapor as humidity fluctuates. This keeps the interior air at a consistent humidity level, preventing mold and fungus and providing cleaner indoor air.
- Because it's hygroscopic, the exterior will not rot from rain and snow as long as it can dry out in between.
- The cons against cordwood can be overcome with good design.
Cons of cordwood:
- Cordwood can shrink as it dries out, causing it to split and pull away from the inflexible mortar and leave gaps.
- Cordwood pieces can become loose in the wall.
- On a poor foundation with frost heaving and poorly chosen and prepared wood, cordwood can expand and cause cracks or structural damage.
- Portland cement used in the mortar is never a great choice in green building because of its high embodied energy and pollution created in its manufacture and transport. But when properly mixed, its longevity can outweigh its bad points.
- Cordwood exposed on end-grain is susceptible to water intrusion, insects and mammals.
- Cordwood requires a lot of mortar to fill out the empty spaces between the irregularly shaped wood pieces, possibly as much as forty percent of the wall surface area. Cob may be a better choice for the mortar since it uses less energy and is easier to repair cracks and gaps.
- Wide roof overhangs are necessary to protect cordwood walls from water.
- Selling the home may be an issue since most buyers are not familiar with cordwood homes.
- Building permits may be difficult to get since building inspectors are also unfamiliar with them and may be skeptical.
In the Greenville, South Carolina area, probably the closest cordwood home was built by Luke and Amy Metzger in Spartanburg in 2008. Luke says "We used red cedar that was debarked and seasoned for 1-1/2 to 2 years. Only the largest of logs shrink in the winter…but only 1/32″ max…we heat with a wood stove. And when the spring returns the logs expand back."
A cordwood cottage outside Saluda, North Carolina, was for sale on the NC MLS several years ago for about $100,000 with some acreage and a stream, but a local bank declined lending on it because it had no gutters nor doors on the closets.
Richard Flateau with Cordwood Construction built his own mortgage-free cordwood home thirty-two years ago in northern Wisconsin. He has written books on the subject, led workshops, and consults on cordwood building. See pictures on his Facebook site for Cordwood Construction.
Rob Roy in West Chazy, New York wrote the book Basic Cordwood Masonry Techniques
and did a video on cordwood building. Cordwood is the basis for his 25 year Earthwood building school, with workshops in West Chazy, Oregon, Indiana and Wisconsin.
There is a free ebook on Cordwood Masonry you can download.
Watch the attached video by Tony Wrench of the cordwood house at Denmark Farm in West Wales going up in 2008.