ADU Construction in Half Moon Bay
Half Moon Bay is a strong market for ADU construction, with options ranging from $175K for a garage conversion to $550K+ for a large detached unit. Custom Home builds detached, attached, and garage conversion ADUs in Half Moon Bay with full 3D visualization and itemized pricing through our two-phase process.
How much does an ADU cost in Half Moon Bay?
Half Moon Bay ADU costs range from $175K-$275K for a garage conversion to $300K-$550K for a detached unit in 2026. Custom Home's two-phase process provides 3D visualization and exact pricing before construction begins.
Why Half Moon Bay is a Strong Market for ADU Construction
Half Moon Bay is a strong market for ADU construction, with property values and rental demand that support the investment. Homeowners use ADUs for rental income, multigenerational living, and home offices. Coastal construction requires salt-air-resistant materials, wind-rated designs, and compliance with the Local Coastal Program.
Custom Home builds ADUs in Half Moon Bay with the same two-phase design-build process we use for custom homes. You see the complete design in 3D and receive itemized pricing before any construction begins.
Types of ADUs We Build in Half Moon Bay
Detached ADUs
A standalone structure in your backyard, typically 400-1,200 sqft. Detached ADUs offer the most privacy and design flexibility. They work well for rental units, home offices, or multigenerational living. Construction costs in Half Moon Bay typically range from $300K to $550K.
Attached ADUs
Built as an addition to your existing home, sharing at least one wall. Attached ADUs are typically more cost-effective than detached units since they share structural elements with the main house. They are a good fit for family members who want proximity while maintaining separate living spaces.
Garage Conversions
Converting an existing garage into a living space is the most affordable ADU option in Half Moon Bay, starting from $175K. Since the structure already exists, you save on foundation, framing, and roofing costs.
Half Moon Bay ADU Permitting
Half Moon Bay’s Building Division administers permits for residential construction within city limits. All projects in the coastal zone must comply with the Local Coastal Program, and properties near sensitive habitats or bluffs may require a Coastal Development Permit. Plan review for custom homes typically takes 8-12 weeks. Custom Home helps clients navigate these layered requirements from the start of the design process.
Custom Home manages the entire ADU permitting process in Half Moon Bay, preparing plans that meet local requirements for efficient review and approval.
ADU Rental Income Potential in Half Moon Bay
Half Moon Bay’s rental market supports strong returns for ADU owners. Estimated monthly rental rates:
- Studio/1-bedroom (400-600 sqft): $2,400-$2,900/month
- 1-bedroom (600-800 sqft): $2,800-$3,500/month
- 2-bedroom (800-1,200 sqft): $3,300-$3,800/month
At these rates, many ADU investments pay for themselves within 7-12 years through rental income alone, not counting the property value increase that a permitted ADU provides.
Pricing for ADU Construction in Half Moon Bay
Half Moon Bay ADU construction costs range from $175K for a basic garage conversion to $550K+ for a large detached unit with premium finishes. Per-square-foot costs typically run $450-$650/sqft. Garage conversions are the most cost-effective option since the structure already exists. Custom Home provides itemized pricing during Phase 1 so you know every cost before committing.
Half Moon Bay Permit Requirements
Half Moon Bay's Building Division administers permits for residential construction within city limits. All projects in the coastal zone must comply with the Local Coastal Program, and properties near sensitive habitats or bluffs may require a Coastal Development Permit. Plan review for custom homes typically takes 8-12 weeks. Custom Home helps clients navigate these layered requirements from the start of the design process. Custom Home handles the entire ADU permitting process, preparing plans that meet local requirements for efficient approval.
ADU Construction in Half Moon Bay: FAQ
What does ADU construction cost in Half Moon Bay?
ADU costs in Half Moon Bay range from $175K for a garage conversion to $550K+ for a large detached unit. The biggest cost factors are ADU type, size, finishes, and utility connections. Custom Home provides itemized pricing during Phase 1 so you know every cost upfront.
How long does it take to build an ADU in Half Moon Bay?
ADU construction in Half Moon Bay typically takes 6-12 months from design to move-in. Garage conversions are fastest at 4-6 months, while detached units take 8-12 months including permits. Custom Home's design phase front-loads decisions to keep construction on schedule.
What size ADU can I build in Half Moon Bay?
California law allows detached ADUs up to 1,200 sqft on most residential lots. Attached ADUs and garage conversions may have different size limits. Custom Home evaluates your specific lot during Phase 1 to determine the maximum allowable size.