Inflated forming techniques coupled with a better understanding of ground temperature control are responsible for a new generation of earth-sheltered buildings. The home described here is made up of a cluster of domed rooms united by arched hallways to create a pleasing and livable structure. The house is built from outside the form with layers of shotcrete or troweled concrete to a thickness of 3 1/2 inches.
SETTING UP THE FORM
The foundation slab is cast with vertical bars embedded at the perimeter for doweling into the dome concrete. The base slab should be at least 3 days old before the dome form is put up. A center scaffold is placed on the base slab, lying flat, and the inflatable form is draped over it so that the scaffold can be set up inside the balloon when it's inflated. The form is inflated by a high-pressure, low-volume blower attached to an inflating tube. The entire dome is covered with 1-inch hexagonal wire mesh. Then a horizontal layer of mesh is applied to a height of 8 feet or more, giving at least two layers over the entire surface of a 20-foot dome.
THE CONCRETE LAYERS
The primary layer of concrete is placed over the wire-covered inflated form, either as wet- or dry-mix shotcrete or by hand troweling. After 3 or more days of curing, the blower is turned off and the form deflated. The resulting shell is then covered with a lattice of #3 reinforcing bars tied to the dowels projecting from the base slab. The second layer of concrete is shot into place to get the total 3 1/2 inches needed.