The Ecohome Demonstration House is well underway, the following page chronicles the first stage of constuction, building the slab-on-grade. The house is oriented facing south to maximize passive solar heat gain in winter, but will be shaded in the summer by deciduous trees, wall mounted sun shades and a large overhang to prevent overheating.
By Mike Reynolds
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Location and orientation of the house on the lot was chosen not only for passive solar heat gain, but to make best use of the terrain for drainage, to limit the cutting of mature trees as much as possible and to ensure a quality of life for occupants with a mix of privacy and usable outdoor space.
After the land was cleared, compacted gravel was brought in to bring the site to a workable level. The house sits at about grade at the north side, but needed about 3.5 feet of fill at the south to level the building site.
Compacted gravel was tamped in stages to ensure a solid base. The machine we used can apparently tamp successfully to three feet deep, we did it every foot and a half for good measure.
A retaining wall was built using rocks from the site to hold the compacted gravel and future slab in place.
It is more common to drive stakes in the ground then nail boards up as concrete forms, but we decided to pre-build forms, then raise and square them the way you would with walls. This was intended to make disassembly easier so we could reuse the wood. Hard to say if it was easier, but it went fine.
Mike Reynolds is a former home builder, a LEED for Homes Green Rater and the editor of Ecohome.net.