Rob Roy's Earthwood Home

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The details: Build on undisturbed earth. Scrape the organic material (topsoil, vegetation) to the edge of the site with a bulldozer. Keep this valuable material. It will be your roof later on. Now, build up a pad of percolating material to a height of about 16". At Earthwood, we spread sand in runs (layers) of about 6" each, then we watered and compacted each run in both directions with a hired power compactor. Three such runs were compacted to a pad about 16" thick.

The concrete footings at Earthwood are 9" thick and 24" wide, with two continuous rings of #4 (1/2") reinforcing bar (rebar) supported about 3" off the bottom of the footing track on clean broken bricks. Prior to pouring, the footing tracks are lined with an inch of Dow Styrofoam Blueboard, which will take a compression load of 5,600 per square foot with only 10% deflection. (The Earthwood walls weigh "only" about 2,000 per square foot, well within the Blueboard's support capability.) The insulation is very important in northern climes. Without it, there is a direct and rapid conduction of heat through the footings to the comparatively cold earth; condensation will occur where the block wails meet the floor. At Earthwood, we have experienced no such condensation.

Using 82 cubic yards of 3,000-poundtest ready-mixed concrete, we poured the wall footings and the central mass (masonry stove) footings. Although it is possible to pour the footings and the concrete slab floor on the same day-called a "monolithic slab"—we chose not to do this. There are a lot of different kinds of preparation required for each pour, and at least a truckload of concrete is required each time, so there is really no advantage in pouring footings and floor at the same time. In fact, the concrete footings provided an excellent guide for pouring and screeding the 4" floor a week later.

Some of the preparations required prior to the floor pour are: installing any under floor plumbing and electrical conduit, installing 1" of extruded polystyrene rigid insulation, and laying down the wire mesh reinforcement. An insurance technique of my own is to snake a 4" perforated drain throughout the sand pad to carry any under slab water away. This drain should terminate above ground, someplace downgrade from the pad. As the concrete is poured, a designated "wire-puller-upper" keeps pulling the mesh up into the concrete. The tines of a rake work well for this. The mesh holds the concrete together when it cracks.

The wet concete is flattened with a long screed board made from a straight two-by-six. I fasten wooden handles to the screed board to make pushing and pulling easier. Next, the floor is "floated" with a bull float with extension handles. Finally, it's troweled smooth, either by hand or with a hired power trowel. Power trowels, with four rotating blades, can be tricky to operate. In fact, I always hire a contractor friend to take charge of the whole pouring process. I let him tell me and my press gang what to do. It's worth it.

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