THE BUILDING OF MOTHER'S STACKWOOD DOME

Enlarge Image Image Gallery [1] The frame of the plywood form is assembled on the concrete foundation, while a pile of cordwood awaits willing hands. [2] Eager seminar attendees lift the truss to a new position as the rear wall of the dome begins to take shape. [3] ""Deadmen "" bristle like porcupine quills on the outside of the structure. They'll be sawed off when they're no longer needed.[4] Two of the volunteer workers invented this ""airmail ""system. [5] Twelve-year-old John Carney did a man's job. [6] The geodesic framework is assembled ... [7] rises to meet the cordwood, and ... [8] is glazed. [9] Cheers! MOM's greenhouse dome is done!

Here's the full story on one of the world's most unusual cordwood structures ...

You may not need an entire 44-foot-diameter, 21-foot-high, geodesic-dome-fronted, wood-wall-backed solar greenhouse like the one that now graces MOTHER's Ecological Research Center ... but-if you're looking for an inexpensive way to construct a solid, well-insulated, dome-shaped structure-the stackwood building method illustrated here is certainly a quick (and easy) one.

In MOTHER NO. 62 (page 33), we told you how-when stackwood expert Jack Henstridge set out to experiment with the low-cost construction technique as a part of last summer's Earth-Sheltered Homes seminar—a whole crowd of folks pitched in, barn raising style, to help create what is (to the best of our knowledge) the world's first stackwood dome.

Needless to say, since our project was a "first", we did a lot of learning as we went along, and there are things that we'll do a little differently when we build our next structure of this type. But we'd still like to tell you how an untested idea (with the help of MOTHER's wonderful summer visitors) became a reality.

STARTING OUT

Our dome began, of course, with the construction of its 44-foot-diameter foundation. This was built on a gravel base ... and the outer three feet (that area which would actually support the wall) is composed of 18-inch-thick cement strengthened with five half-inch reinforcing rods, while the rest of the floor is only four inches thick and firmed up with wire mesh. (Other dome builders might want to make this layer as much as six inches thick, depending upon the load their structure's foundation will bear.)

While laying that "groundwork", we made our first mistake. The drainpipe that channels rainwater away from the "roof" was dug in around the perimeter of the substructure when- actually- it should have been put on the foundation itself. The runoff created some slight undermining, which caused small cracks to appear later. (The problem isn't very serious, but it definitely is avoidable.)

Our next requirement was some 45 cords of wood. Since we decided to use the green logs we had at hand, the timbers had to be split (which, by the way, made for a very interesting and pleasing design on the inner surface of the building). Again, we later discovered that it would have been better to quarter the logs ... to keep shrinkage-as the wood dried out- to a minimum. (If we had used cured wood, this step would not have been necessary at all for any logs smaller than ten inches in diameter.)