Earth-Sheltered Home Kits for Owner-Builders

Image Gallery In typical earth-sheltered home kits, the dome's structural members are bolted together on top of a preformed slab. PHOTO: MOTHER EARTH NEWS STAFF

Financing, contract labor, and raw materials costs have taken their toll of the American own-your-own-home dream in recent years. At the same time, in an effort to seek a new, energy-saving route indoors, many people are now considering housing alternatives that once were shunned by society's mainstream.

Unfortunately, "more efficient" doesn't always mean "less expensive". Take earth-sheltered housing, for example. A decade ago, few folks had ever heard of it, and even fewer understood its advantages. Today, though, soil-covered structures number in the thousands and appear in a variety of styles and sizes. Even so, these subterraneans share one common drawback: All of them must be specifically engineered to withstand the pressures that their earthen blankets invariably subject them to . . . and in many instances, this has required the services of a professional architect and the use of some downright serious structural components.

Well, that may be within the reach of folks who have husky financial resources, but shoestring budgets aren't designed to handle that kind of load. There's no easy way around the dilemma, either. Regional and local building codes universally demand approved engineering on earth-bermed construction for the protection of the residents-to-be . . . effectively quashing any do-it-yourself shortcuts contemplated by the greenback-strapped owner.

Situations such as this beg for solutions, and we've recently heard of an ingenious one you might want to look into: A firm by the name of Earth Systems, Inc., markets a pre-engineered structure that it sells in earth-sheltered home kits. This package differs in at least four ways from the other prefab homes currently available. First of all, it's truly an earth-sheltered design and thus incorporates all the advantages inherent in that kind of building. Second, it's in the shape of a hemispherical dome, which offers an excellent strength-to-material ratio and is freestanding, with no internal supports. Third, the structure is composed of an integral steel framing network covered with a shell of concrete (this monolithic construction eliminates problem seams and joints). And finally, you can purchase the kit shipped complete from the factory, or—if local purchasing of some materials seems more attractive—you can send for part of it and supplement the rest at the building site.

Earth Systems offers an oval dome and a half-dome (open end) structure, as well as the "true" dome shape . . . and their standard kit comes in four sizes with diameters of from 30 to 52 feet. The form is established with a frame of lightweight bolted-together steel beams to which is attached a network of 1/2" reinforcing bar to create a grid of 12" squares. Then a fabric-and-wire panel is fastened to this skeleton, and a 4"-thick covering of concrete—shot from a pressurized gun—is applied to the surface of the structure, with additional material being supplemented at the base. Once that's set, insulation and waterproofing can be added to the outside, and—after a sufficient curing period—the excavation can be back-filled and the house can be covered.