Rob Roy's Earthwood Home

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Cordwood masonry is labor intensive but low in cost. And consider how many jobs are being accomplished at once. A cordwood wall provides: structural support for the roof, insulation, interior and exterior finish, and—the bonus not found in most other walls—usefully positioned thermal mass. The appearance is unique, combining the aesthetics of good stone masonry with the pleasing warmth of wood. When you consider all the layers that go into a stick-frame house (framing, insulation, vapor barrier, Sheetrock, tape, spackle, two coats of interior paint, exterior sheathing, house wrap, siding, two coats of stain, etc.), well ...cordwood comes out pretty well. And the on-cost (maintenance) is practically nil. Our only "maintenance" of Earthwood's cordwood walls has been the occasional caulking around large log ends with a clear, silicone-based caulk. Wait a year or two after building, you'll only need to do this once.

Post-and-Beam Octagon

Earthwood has a strong octagonal internal post-and-beam frame, situated halfway between the external walls and the central stone mass. This frame is necessary to create internal spans short enough to support the heavy earth roof. The floor plan makes use of these beams, too.

Internal walls rise up to meet the underside of the heavy girders, greatly simplifying internal wall finishing. The first floor joists, as well as the heavy (mostly 5" x 10" pine) rafters, are supported by the external walls (cordwood or block) at their outer ends, the masonry mass at the center, and the octagon post-and-beam frame halfway between. This is called a radial rafter system. Actually, only half of the 32 rafters or joists go all the way to the center. Sixteen of them stop at the octagon. The architect-stamped Earthwood plans are engineered to support the 150 pounds per square foot load of a snow-laden and saturated 8" earth roof.

(1) Stone heat sink: 4' diameter upstairs, 5' diameter downstairs.
(2) 16" cordwood masonry wall.
(3) Post locations, seven in all.
(4) Girders, 8" x 8" best Douglas fir or equivalent.
(5) Special girder, 10" x 12" clear oak or equivalent (spans 15').
(6) Primary rafters, 5" x 10" red pine or equivalent for floor joists (4" x 8").
(7) Secondary rafters, 5" x 10" red pine or equivalent for floor joists (4" x 8")
(8) 2" x 6" tongue-and-groove planking.
(9) 2" x 6" plates. S= Special rafters for greater spans, 6" x 10" red pine or equivalent. Floor joists at these locations can be 4" x 8".

Waterproofing the Walls

While there are a variety of good waterproofing membranes on the market, my choice for cost, quality, and ease of application is a rubberized asphalt membrane with a polyethylene top surface, such as the Bituthene 3,000 waterproofing membrane made by W.R. Grace and Co. Similar membranes are manufactured by several other companies, and are commonly used to prevent ice damming on the eaves of shingled roofs.

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