Home Addition in Millbrae
Planning a home addition in Millbrae? Custom Home builds additions at $250-$500 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 Millbrae?
Home additions in Millbrae typically cost $250-$500 per square foot in 2026. A 500 sqft addition ranges from $125K to $250K. Custom Home's design phase locks in your exact cost before construction starts.
Why Expand Your Millbrae Home
Millbrae’s convenient location near transit, SFO, and Peninsula job centers makes it a community where families choose to stay long term. Rather than competing for a larger home in a tight market, many homeowners choose to expand the home they already own. Adding square footage keeps you in your neighborhood while giving you the space your family needs.
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 Millbrae
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. Many of Millbrae’s post-war homes are single-story structures that can be reinforced for a second level. 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.
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 Millbrae Additions
Millbrae 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.
Millbrae Home Addition Permits
Millbrae’s Building Division handles residential building permits. Standard plan review takes 4-6 weeks. The city reviews additions for compliance with zoning setbacks, height limits, and lot coverage requirements.
Custom Home manages the entire addition permitting process, including structural engineering review, plan submittal, and inspection coordination. Our experience with Millbrae’s requirements helps keep the approval process on track.
Pricing for Home Addition in Millbrae
Home addition costs in Millbrae typically run $250-$500 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.
Millbrae Permit Requirements
Millbrae's Building Division handles residential building permits. Standard plan review takes 4-6 weeks. The city reviews additions for compliance with zoning setbacks, height limits, and lot coverage requirements. Custom Home manages the full addition permitting process, including structural engineering review.
Home Addition in Millbrae: FAQ
How much does a home addition cost in Millbrae?
Home additions in Millbrae typically cost $250-$500 per square foot. A 400 sqft room addition generally ranges from $100K to $200K. 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 Millbrae?
Home additions in Millbrae 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 Millbrae 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.