# Basement Structural Engineering Atherton: Deep Foundation Specialists
Atherton, with the highest median home value in the United States exceeding $7.5 million, demands engineering precision matching its extraordinary real estate investments.
Why Atherton Property Owners Build Underground
Atherton's 1-acre minimum lot size creates a unique dynamic: despite large lots, floor area ratio limits and setback requirements restrict above-ground development. Underground space adds square footage without visual impact.
What Atherton Homeowners Build Underground
- **Entertainment**: Full-size home theaters with stadium seating
- **Wellness**: Spas, pools, saunas, and fitness facilities
- **Wine Storage**: Cellars housing 5,000-50,000+ bottles
Deep Basement Engineering Requirements
Engineering for 20-40+ feet of excavation requires comprehensive geotechnical investigation, soldier pile and lagging shoring systems, tie-back anchoring, groundwater management, and permanent waterproofing systems.
Foundation Systems
**Caisson Foundations**: Diameters of 24-48 inches, depths of 30-60+ feet to bedrock or dense soil.
**Mat Foundations**: Thickness of 24-48 inches with two-way bar mats or post-tensioning.
Contact Information
**Town of Atherton Building Division**
- Phone: (650) 752-0500
- Website: ci.atherton.ca.us/building
**Call (949) 981-4448** - Free initial consultation for projects over $25K.