With the beginning of the true third millennium - Y2K wasn't the real thing - I can't help but reflect on the origins of my favorite building method, cordwood masonry, which anecdotal evidence places at around the year 1,000-the beginning of the 2nd Millennium. Another anecdote, the source of which I have unfortunately lost, tells of a 3,000-year-old clay tablet found on Crete with instructions on how to build a cordwood wall.

But before going too far with my ramblings and observations, I acknowledge that there are still some folks out there who don't know what cordwood masonry is, and others who have heard of cordwood construction but dismiss it as unsound, funky, or worse. So, in modern computer parlance-and I am assuredly not a computer freak, preferring to stay on the blunt edge of technology-I will address some "FAQs" (frequently asked questions) which I hear all the time at Earthwood or at our booth at the Midwest Renewable Energy Fair.

Earthwood, built in 1981-82, has two full stories and is earth-sheltered. Satellite buildings include the small round sauna to the right and the 20-foot diameter office to the left. Photovoltaics and a windplant provide the electrical energy, raised beds furnish food, and the stone circle attends to spiritual needs.

What the heck is cordwood masonry?

Cordwood masonry is low in cost, easy to do, highly energy efficient when done right, environmentally sound, and quite beautiful to look at if a modicum of care is taken during construction.

Sounds too good to be true.

(While not strictly a question, the person saying it really wants more information, so I try to accommodate.) Yes, I know. Maybe that's why so many people are suspicious of it and claim it won't work. And, in truth, like any other building method, it can be screwed up. Cordwood guru Jack Henstridge from New Brunswick, says, "Cordwood masonry is very forgiving, but it won't forgive stupidity." Fortunately, there is so much information available on cordwood now, that ignorance is no longer an excuse. My wife Jaki and I, and other early modern cordwood builders, have made plenty of mistakes, but we have tried to share these mistakes with others so they don't have to endlessly repeat them, as in that special corner of Hell reserved for those who don't learn from experience. My late father used to say a smart man learns from his mistakes, but a wise man learns from the mistakes of others. It goes for women, too.

How have people screwed up?

Oh, lots of ways, and all easily avoidable. Some don't take the bark off the wood, and eventually, when the wood finally shrinks away from the bark, there is this wonderful habitat for certain small insects. Others don't dry the wood long enough, and there are great shrinkage gaps around each log end. Fortunately, this is mainly a cosmetic problem (or, in the extreme, an air infiltration problem), and can be attended to a year or so after the home is completed. Conversely, some have built using hardwoods which are too dry. While rare, this problem is more serious than wood shrinkage. When the dry wood takes on moisture from, say, a driving rainstorm, the wood can expand and actually break up the wall. Expanding wood can raise the top plate beam and/or cause massive corner posts in a heavy timber frame to tilt out. At Earthwood, we saw expanding dry hardwood take the curved walls three inches out of plumb. Prior to that experience, we had always had good luck using very dry wood, but it had always been white cedar, which is much more stable, both in shrinkage and expansion. In 1981 we didn't know about the dangers of hardwood expansion, but we do now, and try to steer others away from the problem.

What did you do when the walls were three inches out of plumb?

For extra thermal mass, we chose hardwood for the earth-sheltered (below grade) part of the house, and used the dry white cedar above grade for better insulation. We tore the hardwood walls down and replaced them with surface-bonded concrete blocks, which are quick and easy to do, are nice and bright below grade, and have good thermal mass. We put Bituthene waterproofing membrane (W.R. Grace and Co.) on the outside and covered that with two inches of extruded polystyrene for insulation. That way, the 90-odd-tons of sand-filled blocks became a thermal mass over which we can exercise control. I guess we made lemonade out of lemons, but I don't mind saying that five weeks of building walls and tearing them back down again was not the happiest time of my life.

My father (or brother-in-law or local contractor or neighborhood know-it-all) says that wood will rot out when placed against concrete. He says Rob Roy is a jerk.

Done wrongly, that can be a problem. But it is not a problem with cordwood masonry, because we lay the wood transversely in the wall, so that the log ends can breathe along the longitudinal wood fibers. Wood rot is caused by fungi, microscopic critters which literally eat the wood. But fungi need three things to survive: air, nutrients, and moisture. If any of these things are missing, the fungi do not have a favorable climate to propagate and do their nasty little deeds. (Actually, they are not nasty at all-they're just trying to survive and continue their species, like the rest of us.) A cordwood wall may get soaking wet from a horizontal rain, but, because of its wonderful breathability, it dries within days, and the fungi do not get a foothold. People think a split-rail fence lasts for 40 years because it is made of cedar, which has some magical resistance to rot. But this is not so. It lasts in good condition because it is breathing so wonderfully high off the ground. Lay one of those rails in the soil for just a year, and it will rot, guaranteed.

Oh, and while it is entirely possible that Rob Roy is a jerk, I resent that remark.

Did you say your house is round? Why would anybody build a round house?

There is an ancient Scottish Highland saying: "Ye may as well hang for (stealing) a sheep as a lamb." Once someone has made it past the naysayers and decided to build of cordwood masonry, they have shown that they are able to "think outside of the box," so the leap to a round house isn't quite so severe. But it's a slippery slope. The danger is that they may progress (or regress, same thing) to building stone circles. Seriously, round houses make a lot of sense. Humankind is the only building species that goes with right-angled corners. Birds, bees and beavers (who built lodges with a kind of cordwood masonry) all build round. Without benefit of a course in geometry, they know that the round house uses the least amount of materials to enclose a desired space. The same advantage is there when it comes to heat loss. A round home is cozy. Wombs are not rectangular. But, if you like square corners, that's okay. You can build any shape with cordwood, even free-form, as long as the walls are vertical. Jaki and I would feel strange now, living in a house which is not round. Even our summer camp is round, and our cordwood sauna is the coziest building I know. Our garage is rectilinear, though. A round garage is a poor use of space and doesn't handle wide doors very well.

You say cordwood masonry is energy efficient, yet the wood breathes so well. Isn't that a contradiction? Also, won't the mortar conduct the heat right out of the house?

Whoa, easy, one at a time. If large shrinkage caps are left unattended, yes, there would be severe infiltration. This has not happened with any of our buildings, although our first cordwood home, Log End Cottage, was not energy-efficient because the walls were only nine inches thick. Purely and simply, this is not enough insulation (about R9) for our climate in Northern New York of about 9,000 degree days. We advise a minimum of 16" thick walls and it is common in Canada for cordwood builders to go with 24" thick walls or even greater. The 16" cordwood walls at Earthwood are about R19, minimum code for New York. But our walls have another thermal advantage not even addressed by the code. And the second question about mortar is directly related to this.

“Mushwood” is the name of the Roy’s summer camp on Chateaugay Lake, New York. The 22-foot diameter cordwood first floor supports a 29-foot geodesic dome, covered with cedar shingles.

Unlike the log-ends, the mortar does not go all the way from the inside to the outside of the wall. There is a critical insulated space between the inner and the outer mortar joints. The mortared portion of the 16" walls at Earthwood consist of five inches of mortar, six inches of loose-filled insulation, and five inches of mortar. (We use sawdust as an effective, low-cost, environmentally sound insulation.) By this juxtaposition of insulation and thermal mass, the many tons of the inner mortar joint become an effective mass heat storage device, a heat capacitor, if you like. Before the temperature of the air inside the house can go down, the stored heat of the inner mortar joint would have to be used up, and, to some extent, the log-ends as well. The modern stick-frame house with R19 insulated walls does not have this reservoir of heat to help keep the house at a steady temperature.

People are surprised to learn that 40-50% of a cordwood wall's area is the mortared portion. They are also surprised that the mortared portion also has the superior thermal characteristics, what I call that wonderful and perfect juxtaposition of thermal mass and insulation.

In fairness, I have to say that Earthwood's energy-efficiency is a function of five different variables. An important one is certainly the cordwood masonry used for above-grade walls. But there is also: 2. the round shape, already mentioned; 3. the fact that 40% of the cylindrical wall shape is earth-sheltered, effectively setting the house 1,000 miles further south as far as climate is concerned; 4. the fact that we burn most of our firewood through a 23-ton masonry stove, the most efficient way to burn wood, and; 5. good solar orientation. On the last point, it is important to keep in mind that any house we can design and build, energy-efficient or inefficient, can be up to 30% more efficient if it is oriented correctly with respect to the sun's path. Here in the north, where heating is the more important energy consideration, we want to face the house to the south for solar gain. A town near us has a zoning code that says the house must be built "parallel to the road." Never mind which way the road runs. Such a code could cause a 30% higher energy bill in an entire neighborhood. A round house will fox this code enforcement officer, and be energy-efficient.

And just how energy-efficient is Earthwood?

Well, as they say, the proof is in the pudding. Earthwood is 2,400 square feet of gross space-about 2,000 square feet actual usable within the thick walls-and we heat the building with 3-1/4 full cords of wood each year, about 10 face cords of 16" wood. Some years we buy hardwood slabs from a sawmill for burning in our masonry stove, and pay about $100 for a full winter's fuel supply, delivered. The wood comes banded in four-foot lengths, so, with just one chainsaw cut, we can divide the ring of wood into two smaller cylinders of 24" pieces, just right for the masonry stove. For the past two years, we've been cutting up wood from the horrendous ice storm of '98.

But Earthwood's most defining thermal characteristic is its steady temperature, summer and winter. It takes a long time to change the temperature of 240 tons of something. We are warm in winter, cool in summer.

There are other questions people ask. What kind of wood to use? How long should I dry it? What is your mortar recipe? Which way is up? But some of these are can-of-worms type questions, and require a response as long as the 2,051 words my 'puter tells me I've already burned. Another time, perhaps. And please, patient reader, feel free to send your questions to Countryside and we can chat again.

The sauna is 10 feet in diameter, with eight-inch cordwood walls. A sauna would make an excellent first-time practice project.

I wanted to finish with a first report on an exciting new (or is it really old?) cordwood concept that Jaki and I have been experimenting with, along with Ianto Evans and Linda Smiley of Cob Cottage Company in Oregon. (Cob Cottage Co., Box 123, Cottage Grove, OR 97424; (www.deatech.com/cobcottage) Some builders, particularly those in the Natural Home Building field, take exception to the use of Portland cement, pointing out, quite rightly, the negative environmental and energy considerations of the manufacturing process of Portland cement. I won't-or can't-argue the point. Our mortar recipe performs very well, but contains Portland cement and hydrated lime. Cob, on the other hand, is a natural material composed of roughly 80% coarse sand and 20% clay, with straw used as reinforcing material.

Inspired by Tony Wrench, who built an environmentally compatible cordwood-and-cob round house in Wales, we began to build test panels of cordwood masonry at Earthwood, using Ianto and Linda's cob mix for mortar, instead of our cement-based mud. Preliminary results are very encouraging, and, at the Natural Building Colloquium in Kingston, New Mexico last November, we did some more "cobwood" with Linda and Ianto. We also learned that Steen Moeller of Soender-Felding, Denmark, has done some nice work in cordwood and cob construction. I will be doing a cordwood and cob-or cobwood-workshop at Fox Maple School in Maine, June 4-9, 2001. (Fox Maple School, PO Box 249, West Brownfield, ME 04010; (www.foxmaple.com) And, of course, we will continue to offer "regular" (mortar-based) cordwood construction at Earthwood Building School. (See below for contact information.)

I do not believe that cobwood will replace ordinary mortar-based cordwood masonry, but the concept may provide a viable alternative for those who are natural building purists. Mixing cob, in our experience, is more time-consuming than mixing mortar, but if the owner-builder has favorable soils on site, cobwood may offer a lower cost alternative, one which makes good use of indigenous materials. My guess is that cordwood work being done 1,000 years ago in Scandinavia, the Greek Mountains or in Siberia was more likely to have been done with a clay-based (as opposed to cement-based) mortar. Perhaps we are coming full circle in this new millennium. Stay tuned. . .

Rob Roy, author of The Complete Book of Underground Homes, The Complete Book of Cordwood Masonry Housebuilding, Mortgage Free: Radical Strategies for Home Ownership, Stone Circles: A Modern Builder's Guide to the Megalithic Revival, and The Sauna, is director of Earthwood Building School, 336 Murtagh Hill Rd., West Chazy, NY 12992; ph. (518) 493-7744. He will be at the Midwest Renewable Energy Fair, in Amherst, WI, June 22-24, 2001.

Earthwood conducts two-to-five-day workshops in cordwood masonry, earth-sheltering and megalithic stone construction, and acts as a clearing house for books and videos on these subjects. Write or call for free information, or visit: (www.cord-woodmasonry.com).