Underground Home Construction Methods

Bermed Construction

• Bermed homes are built slightly below ground elevation with one side open and the other sides and roof covered entirely by earth. They are also constructed on an above ground elevation; soil is then packed around the house and on its roof. Both types of construction require waterproofing and insulation. Wing insulation protects the dwelling's foundation from moisture and frost. Wing insulation entails running alternate horizontal layers of protective sheeting and straw out from the structure's foundation; top soil is then backfilled over the layers.

Fully Underground Construction

• Fully underground homes sit below ground level and have flat roofs. Underground homes have from three to nine feet of earth on top of them. Building a fully underground home off of an open center provides better cross ventilation and allows for some natural light. Building the house around a hub also allows more home design choices and scenic variety. A fully underground home is not necessarily more energy efficient than its bermed counterpart. Underground homes lose some of their passive heat capacity due to lack of sun exposure.

Advantages and Disadvantages

• Bermed earth homes generally cost less than homes built totally underground. Both construction methods accrue the primary advantage of underground construction: energy efficiency. Increased home security from natural occurrences such as storms as well as from intruders is another advantage of underground home construction. For many, bermed homes offer more aesthetically appealing design choices. They also provide better cross ventilation and more natural light than fully underground construction methods. Both types of construction can suffer from drainage problems as well as earth settling and shifting.

Construction Considerations

• Underground construction works best in regions with widely fluctuating seasonal temperatures; in these areas, the temperature of the earth remains more stable than the temperature of the air. The prevailing climate directs whether the home should be built facing north or south. Sandy soils bode better for construction than denser soils which swell when wet and lack porosity. The soil should also be sampled for contaminants prior to building. Ascertaining the water table and mapping the area for seasonal drainage patterns are also imperative.