Throughout most of the revival period, cement-based mortars have been used in cordwood building. In recent years, however, there has been more experimentation with cob-based mortars, which makes the building ever more ecological, but requires careful attention to getting the right mix (Roy, 2002). Wood selection and preparation are also factors. Cordwood construction allows great variety, and rule number one is usually use what youve got. But if there is a choice, lighter airier woods such as white cedar, spruce and poplar provide more insulation and more stability than more dense hardwoods. The wood should be well (air-) dried, and thoroughly debarkedsince bark can harbour organic material that can cause decay. Typically the logs are not coated with a moisture barrier, but are allowed to breathe naturally. Sometimes other materials are included in the mix, such as bottle ends that would permit light to enter the wall (Roy, 1992). Cordwood masonry is a good building form for community development and owner-building. It is labour-intensive but fairly simple. It is more energy-efficient than most earth-building modes, with buildings tending to be warm in winter and cool in summer. Cordwood buildings utilize wood waste, but they do require enormous amounts of wood, especially the post-and-beam method. If using cement mortars, one also increases the embodied energy of the building. And while durable, cordwood masonry tends to require a fair amount of maintenance, especially after a year or two, to seal shrinkage or expansion cracks. None of these drawbacks seem overwhelming, however, and in northern forested climates like much of Canada, cordwood provides an appropriate building form to nurture and generalize. For the right situation, it can be an economic and sustainable choice.