Home Addition in Atherton
Custom Home builds home additions in Atherton at $700-$1000 per square foot. Whether you need a second-story addition, ground-floor expansion, or bump-out, our two-phase process delivers 3D visualization and itemized pricing before construction starts.
How much does a home addition cost in Atherton?
Home additions in Atherton typically cost $700-$1000 per square foot in 2026. A 500 sqft addition ranges from $350K to $500K. Custom Home's design phase locks in your exact cost before construction starts.
Why Expand Your Atherton Home
When your Atherton estate needs more space, expanding the existing structure preserves your established location, mature landscaping, and neighborhood standing while adding the rooms and features your family needs. Established neighborhoods and proximity to both San Francisco and Silicon Valley create consistent demand for quality construction.
Custom Home designs and builds home additions with the same two-phase process we use for custom homes. You see the complete addition in 3D and receive itemized pricing before construction begins.
Types of Home Additions We Build in Atherton
Second-Story Additions
Double your living space by building up rather than out. Second-story additions are ideal when lot coverage limits prevent ground-floor expansion. Custom Home’s structural engineers evaluate your existing foundation to determine what reinforcement is needed.
Ground-Floor Room Additions
Extend your home’s footprint with new bedrooms, family rooms, or home offices. Ground-floor additions integrate with your existing layout and maintain single-level living, which is especially valued in Atherton.
Bump-Outs and Extensions
Smaller expansions that make a significant difference: extend your kitchen, enlarge a bathroom, or add a sunroom. Bump-outs typically cost less and complete faster than full additions.
Structural Considerations for Atherton Additions
Atherton is located in a seismically active region, which means home additions must meet current seismic codes. Custom Home’s engineering team handles foundation evaluation, load-bearing wall modifications, and seismic design for every addition project. Whether you are adding a second story or expanding your footprint, structural engineering is included in our Phase 1 design process.
Atherton Home Addition Permits
Atherton’s Building Division reviews all residential construction applications with particular attention to tree preservation, setbacks, and neighborhood character. Plan review for custom homes typically takes 6-10 weeks. Heritage tree removal requires a separate permit and arborist report. The town’s design review process applies to all new construction and significant exterior modifications.
Custom Home manages the entire addition permitting process, including structural engineering review, plan submittal, and inspection coordination. Our experience with Atherton’s requirements helps keep the approval process on track.
Pricing for Home Addition in Atherton
Home addition costs in Atherton typically run $700-$1000 per square foot, similar to new construction pricing. Second-story additions may cost more due to structural reinforcement requirements. Custom Home's Phase 1 design process locks in exact pricing before construction begins.
Atherton Permit Requirements
Atherton's Building Division reviews all residential construction applications with particular attention to tree preservation, setbacks, and neighborhood character. Plan review for custom homes typically takes 6-10 weeks. Heritage tree removal requires a separate permit and arborist report. The town's design review process applies to all new construction and significant exterior modifications. Custom Home manages the full addition permitting process, including structural engineering review.
Home Addition in Atherton: FAQ
How much does a home addition cost in Atherton?
Home additions in Atherton typically cost $700-$1000 per square foot. A 400 sqft room addition generally ranges from $280K to $400K. Second-story additions may cost more due to structural reinforcement. Custom Home locks in exact pricing during Phase 1.
How long does a home addition take in Atherton?
Home additions in Atherton typically take 6-12 months from design to completion. Second-story additions require 8-14 months due to additional structural work. Custom Home's design phase ensures construction runs efficiently and on schedule.
Can my Atherton home support a second-story addition?
Most homes can be structurally reinforced for a second story. Custom Home's engineering team evaluates your foundation and framing during Phase 1 to determine what modifications are needed and includes those costs in the itemized scope.