Wood is the oldest material used by humans for construction after stone. Despite its complex chemical nature, wood has excellent properties which lend themselves to human use. It is readily and economically available; easily machinable; amenable to fabrication into an infinite variety of sizes and shapes using simple on-site building techniques. Wood is exceptionally strong relative to its weight, it is a good heat and electrical insulator and more important - it is a renewable and biodegradable resource.