Home Addition in Los Altos Hills
Custom Home builds home additions in Los Altos Hills at $600-$900 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 Los Altos Hills?
Home additions in Los Altos Hills typically cost $600-$900 per square foot in 2026. A 500 sqft addition ranges from $300K to $450K. Custom Home's design phase locks in your exact cost before construction starts.
Why Expand Your Los Altos Hills Home
When your Los Altos Hills 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. Silicon Valley’s tech-driven economy supports strong demand for modern, energy-efficient residences.
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 Los Altos Hills
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 Los Altos Hills.
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 Los Altos Hills Additions
Los Altos Hills 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.
Los Altos Hills Home Addition Permits
Los Altos Hills processes building permits through its Planning and Building Department. All new construction requires review by the Architectural and Site Control Commission, which evaluates design, grading, tree preservation, and compatibility with the town’s rural character. Plan review typically takes 6-10 weeks due to the additional environmental and site considerations.
Custom Home manages the entire addition permitting process, including structural engineering review, plan submittal, and inspection coordination. Our experience with Los Altos Hills’ requirements helps keep the approval process on track.
Pricing for Home Addition in Los Altos Hills
Home addition costs in Los Altos Hills typically run $600-$900 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.
Los Altos Hills Permit Requirements
Los Altos Hills processes building permits through its Planning and Building Department. All new construction requires review by the Architectural and Site Control Commission, which evaluates design, grading, tree preservation, and compatibility with the town's rural character. Plan review typically takes 6-10 weeks due to the additional environmental and site considerations. Custom Home manages the full addition permitting process, including structural engineering review.
Home Addition in Los Altos Hills: FAQ
How much does a home addition cost in Los Altos Hills?
Home additions in Los Altos Hills typically cost $600-$900 per square foot. A 400 sqft room addition generally ranges from $240K to $360K. 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 Los Altos Hills?
Home additions in Los Altos Hills 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.
Do I need to move out during a home addition in Los Altos Hills?
For most additions, you can remain in your home during construction. Second-story additions may require temporary relocation during certain phases. Custom Home plans the construction sequence during the design phase so you know what to expect.