Expand Your Home Without Moving
Second-story additions, room expansions, and more. Designed in 3D before we build.
Love your neighborhood but need more space? Custom Home designs and builds home additions that blend seamlessly with your existing structure. From second-story additions to ground-floor expansions, we bring deep structural engineering expertise to every project.
Years in the Bay Area
Licensed since 2005. Hundreds of projects completed across the South Bay, Peninsula, and beyond.
BuildZoom Rated
Ranked in the top 1% of Bay Area contractors based on qualifications, performance, and reliability.
Design-First Process
See every detail in 3D before construction. Our two-phase approach separates design from build so you never commit blind.
Change Orders
When you follow our full two-phase process from A to Z, every decision is locked in during design. No mid-project surprises.
Itemized Pricing
Every material, every line item, visible before you sign. No allowances, no hidden fees.
Why Choose Custom Home for Home Additions
Second-Story Additions
Double your living space by building up. Our structural engineers ensure your existing foundation can support the addition.
Room Additions
Expand your footprint with new bedrooms, family rooms, or home offices that integrate with your existing layout.
Bump-Outs & Extensions
Smaller expansions that make a big difference: extend kitchens, enlarge bathrooms, or add a sunroom.
Structural Expertise
Load-bearing wall modifications, foundation work, and seismic considerations handled by experienced engineers.
What to Expect
Every addition is different. Cost varies based on structural requirements, finishes, and whether the addition is ground-floor or second-story.
Key Cost Factors
- Addition type (ground floor vs second story)
- Structural reinforcement needs
- Material and finish selections
- Permit and engineering requirements
- Square footage
All pricing is approximate and subject to change. Every project is unique, and final costs are determined on a project-by-project basis during our design phase.
Ready to discuss your home additions project? Call (888) 306-1688 or schedule a consultation.
Frequently Asked Questions
How much does a home addition cost in the Bay Area?
Home addition costs are a real concern for Bay Area homeowners. Additions typically range from $250 to $500 per square foot, similar to new construction costs. Second-story additions may cost more due to structural requirements. Our design phase locks in your exact cost before we start, so there are no surprises.
Can my home support a second-story addition?
Most homes can be structurally reinforced for a second story. Our engineering team evaluates your foundation and framing during the design phase to determine what modifications are needed.
How long does a home addition take?
Most home additions take 6-12 months from design to completion. Second-story additions typically require 8-14 months due to additional structural work and permitting.