How Much Does It Cost to Build an ADU in Long Beach in 2026?
- Josh Alvarez
- Apr 4
- 3 min read
Updated: Jun 7
Accessory Dwelling Units (ADUs) continue to be one of the most popular ways for California homeowners to increase property value, generate rental income, and create flexible living space for family members. Whether you're considering a detached backyard cottage, garage conversion, or attached ADU, understanding the costs involved is one of the first steps toward a successful project.
At Alvarez Design Build, we help homeowners throughout Long Beach and surrounding communities navigate the entire ADU process, from feasibility studies and architectural design to permitting and construction.
What Is an ADU?
An Accessory Dwelling Unit (ADU) is a secondary residential unit located on the same property as a primary residence. ADUs can be used for:
Rental income
Multigenerational living
Housing aging parents
Guest accommodations
Home office space
Future downsizing opportunities
California's ADU laws have made it easier than ever for homeowners to add legal housing to their property while increasing long-term property value.
Average ADU Construction Costs
The cost of building an ADU depends on several factors including size, site conditions, utility requirements, and finish selections.
Detached ADU
A detached ADU is a standalone structure located in the backyard.
Typical Cost Range:$350,000 - $500,000+
Average Cost Per Square Foot:$350 - $450 per square foot
Attached ADU
An attached ADU shares at least one wall with the primary residence.
Typical Cost Range:$250,000 - $400,000+
Average Cost Per Square Foot:$300 - $425 per square foot
Garage Conversion ADU
Converting an existing garage is often one of the most affordable ADU options.
Typical Cost Range:$125,000 - $250,000+
The final cost depends on existing utilities, structural modifications, insulation upgrades, and required code improvements.
Factors That Impact ADU Costs
Size of the ADU
Larger units generally cost more overall but may have a lower cost per square foot due to economies of scale.
Site Conditions
Properties with difficult access, utility upgrades, grading requirements, or demolition needs can increase construction costs.
Utility Connections
Costs may include:
Electrical upgrades
New sewer connections
Water line upgrades
Gas service modifications
Design Complexity
Vaulted ceilings, large glass openings, custom kitchens, luxury bathrooms, and premium finishes can significantly impact budget.
Permits and Professional Services
An ADU project typically requires:
Architectural plans
Structural engineering
Energy calculations
Surveying
Permit fees
Construction management
How Much Rental Income Can an ADU Generate?
Many homeowners view ADUs as a long-term investment.
Depending on size, location, and amenities, ADUs in Long Beach may generate approximately:
Studio ADU: $1,800 - $2,400/month
One-Bedroom ADU: $2,000 - $2,800/month
Two-Bedroom ADU: $2,500 - $3,500+/month
Actual rental rates vary based on market conditions and property location.
Does an ADU Increase Property Value?
In many cases, yes.
An ADU can increase:
Property value
Rental income potential
Buyer demand
Flexibility for future family needs
Many homeowners find that an ADU provides both immediate functionality and long-term financial benefits.
Why Work With a Design-Build Team?
One of the biggest challenges homeowners face is coordinating between architects, engineers, consultants, contractors, and city agencies.
With a design-build approach, the entire process is managed under one roof.
Benefits include:
Single point of contact
Streamlined communication
Faster project delivery
Better budget control
Reduced design conflicts
Improved construction coordination
At Alvarez Design Build, we provide both architectural design and construction services, allowing homeowners to move from concept to completion with confidence.
Start Planning Your ADU Today
Every property is unique, and the best way to determine the feasibility and cost of an ADU is through a professional evaluation.
Our team can help you understand:
Whether your property qualifies for an ADU
The maximum allowable size
Estimated construction costs
Rental income potential
Design options that fit your goals and budget
If you're considering an ADU in Long Beach, Lakewood, Cerritos, or the surrounding areas, Alvarez Design Build is here to guide you through every step of the process.
Contact us today to schedule a Pre-Design Consultation and begin exploring the possibilities for your property.
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