Designing an Earth Sheltered Home should not be taken lightly. Conserations for structural stability, service realities, duribility and moisture intrusion must each be handled adequately, and with the highest level of care.
Discussed herin will be an approximately 7000 square foot reinforced concrete earth-sheltered residential project.
Initial Structural Study:
- Subsurface Geotechnical Exploration
- Topographical Survey
- Subsurface Rock Formation Exploration
- Material Availability & Cost
- Geographic Location
- Contractor Capabilities
Structural Design Considerations:
- Slope Stability
- Sliding Resistance
- Overturing Resistance
- Retaining Wall Drainage
- Rainwater Runoff
- Seismic Load
- Differential and Local Settlement
- Expansion & Contraction
- Material Compatibility
We started our design with a clean slate on a large open lot. Our geotechnical engineer generated a subsurface rock formation profile that indicated we had rock approximatley 5 to 10 feet below grade with pinnacles and troughs to be expected. We located the foundation bearing elevation by taking into consideration the potential for blasting costs, differential and local foundation settlement, borrow and fill expectaions and availability and cost of structural fill.
For our structural skeleton, reinforced concrete was the obvious choice. The inital design considered an approximately 20 foot tall (2 levels) reinforcend concrete retaining wall at the rear (& highest point of existing grade) with reinforced concrete eleveated floor and roof plates. Lateral sliding forces are transmitted through the second level concrete floor deck and the basement slab on grade to perforated reinforced concrete shear walls spaced approximately 30 feet on center along the lenth of the structure (120′-0″ length). Lateral wind pressures are transmitted through the plywood shathing roof diaphragm and pre-engineered wood trusses to the shear walls below. Exterior finished grade at the rear of the structure is approximately 12″ below the bearing elevation resulting in very low lateral pressures on our wood frame diaphragm.
As of 08.21.2011, we are at 50% progress. Go to Part 2