Cordwood - Alternative Building Association
Text by Richard Flatau of Cordwood Construction
Cordwood buildings have been found in Siberia and Greece as far back as 1000 years ago. More modern structures have been found around Europe, the Americas and Asia.
Cordwood also known as log end or stackwall construction has been undergoing a continual evolution since its rediscovery in the early 70′s. The Cordwood Conferences of 2005 and 2011 brought the best minds and builders in the field together to discuss improvements and demonstrate new methods using cordwood construction.
From the work at and after for use with cordwood these conferences, a set of Best Practices and test data emerged.
Like all building decisions there are continual cost/benefit/budget choices that must be made before and during construction. There is no absolute right way to build your home, rather there are decisions that you must make based upon available money, skills, time and preferences. Here are some. The list is not exhaustive or complete, it is continually being added to and improved:
- Foundations: Most cordwood builders use an insulated frost protected shallow foundation (FPSF). Many are putting radiant-in-floor heat into the slab
- Post and Beam Framing: Most cordwood experts now agree that one of the advantages of post and beam framing, is that you can put your roof on first. That allows you to do the cordwooding out of the elements, it gives you a covered space to store all of your log-ends, tools and supplies. It gives you the opportunity to build one section of wall at a time. If winter comes early, simply side up the sections that aren’t finished and finish them in the spring
- Wood Prep & Drying: The biggest problem with cordwood is the natural tendency of the mortar to separate from the wood. This is why it is very important to dry your wood to the minimum moisture content (EMC) for your area.
- Pick your R-Value: 16″ will give R-24. 1.5 per inch of wall.
- Wood choices: Cedar is the ideal wood for cordwood. However, except for staying away from hardwoods (they have a tendency to swell and crack mortar joints) most of the other dry, insect free softwoods are suitable for cordwood building.
- Mortar Mix: The mortar mix must be one that will set up and cure slowly. There are about five basic mixes (traditional cement based mortar, Lime Putty, Cob, Paper enhanced and Cellulose enhanced) Some will leave your walls smooth and others will have an adobe like quality. Before you make a decision it is wise to try a few of the mixes and see what they look and feel like after you mortar.
- Large Overhangs & gutters: In order to keep the cordwood dry and free from splashback, it is a good idea to have at least a 24” overhang
- Code Compliance: One of the main thrusts of the Cordwood Conference 2005 was to establish a document that dealt with Code Issues. Fortunately the document Cordwood & the Code: A Building Permit Guide was one of the gems produced for the Conference.
- Solar design: Consider passive and active solar design options. If you can’t afford them right now at least keep a solar window open for later attachment.
- Practice Building: Learn the cordwood technique, gain valuable storage space, learn how to mix mortar and tuck point. This is a win/win.
- Take a Workshop: Work on a cordwood project, go visit a cordwood home, consult with someone who has built and lives in a cordwood home. These will be your experts.
The latest book to hit the bookstores is Cordwood Construction Best Practices (2012) which gives the reader a detailed and complete account of the choices available to the “wood-be” builder.
A list of websites and blog sites also give a rather comprehensive pictorial view of cordwood homes, cabins and cottages throughout the world.
- Interesting Cordwood Build With Sand Bag Foundations - http://www.daycreek.com/dc/asp/forum2002/display_topic_threads.asp?ForumID=2&TopicID=2795