Home Addition in Hillsborough

Why Expand Your Hillsborough Home

When your Hillsborough 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 Hillsborough

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 Hillsborough.

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 Hillsborough Additions

Hillsborough 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.

Hillsborough Home Addition Permits

Hillsborough’s Building Division processes residential permits with oversight from the Architecture and Design Review Board (ADRB). All new construction and significant exterior changes require ADRB approval, which evaluates design quality, neighborhood compatibility, and landscape plans. Plan review typically takes 6-10 weeks. The town requires detailed material specifications and color boards as part of the review package.

Custom Home manages the entire addition permitting process, including structural engineering review, plan submittal, and inspection coordination. Our experience with Hillsborough’s requirements helps keep the approval process on track.