posted 12 years ago
Red cedar is quite a bit more dense than northern white cedar, only about two-thirds of the R-value. So walls must be thicker to get the same insulation quality. Also, red cedar shrinks more than white cedar. It really performs more like a hardwood. Rot is rarely a problem with any species of wood, because of cordwood masonry's unique breathability.
There are several kinds of red cedar, including aromatic red cedar, used in cedar closets to discourage moths in the woolens. Be careful using a lot of this, as the aroma can be overwhelming. One lady I heard of had a sauna built for her out of red cedar boards and she could not use it; at 150+ degrees, you could not breathe in the room. It was not cordwood, but cordwood would not have been any better, maybe worse.
Finally, to conclude on a positive note, I know of an excellent Earthwood type cordwood house in North Carolina built out of red cedar that was brought down on a flatbed from Maine. Beautiful, very successful home, no aroma issues, an unqualified success.