Get a quick, early look at what you can build before investing in a full ADU feasibility study.
Curious about adding an accessory dwelling unit (ADU)—sometimes called a backyard home—to your property? This ADU basics guide explains what ADUs are, how they work in California, and the key steps to plan a code-compliant, livable, and value-adding home on your lot.
What Is an ADU?
An ADU (Accessory Dwelling Unit) is a secondary, self-contained home on the same lot as a primary residence. It has its own kitchen, bathroom, sleeping area, and entrance.
Common ADU types
- Detached ADU: A separate backyard cottage.
- Attached ADU: Shares a wall with the main home.
- Conversion ADU: Transforms space like a garage, basement, or attic into a legal dwelling.
- JADU (Junior ADU): A smaller, efficiency-style unit carved from existing space (has specific rules).
Why build one? Multi-generational living, space for caretakers, future flexibility, potential rental income, and long-term property value.
ADU Requirements: The Basics You Should Know
Zoning & Development Standards
Local rules shape size, height, setbacks, lot coverage, and parking. These vary by city and county, so a quick property check is the smartest first step.
Permits & Inspections
ADUs must be permitted and pass inspections (life safety, energy, and habitability). A code-compliant ADU protects your investment and resale value.
Utilities & Site Conditions
Plan early for sewer, water, and power capacity, trenching routes, and proper drainage/grading. Clear access paths and fire/life-safety requirements also matter.
Design for Real-Life Living
Prioritize livability: natural light, privacy, furniture-friendly layouts, storage, and a real kitchen. Thoughtful design makes small spaces feel big—and keeps maintenance low.
ADU Costs, Timelines & Tradeoffs (High Level)
- Scope drives cost. Structural upgrades, utility distances, and finish selections affect budgets.
- Timelines vary. Permitting timelines change by jurisdiction; standardized plans can help.
- Quality matters. Durable materials and a proven process reduce change orders and delays.
(Tip: Beware of “lowest-bid” scope gaps that lead to expensive change orders later.)
Build Pathways: Which Approach Fits You?
- Build Ready ADUs: Pre-designed, engineered plans with curated finishes and predictable timelines. Great for speed and clarity.
- Custom ADUs: Tailored layouts and architecture for unique sites, aesthetics, or multigenerational needs.
- Garage Conversions: Cost-effective if the structure and slab can meet habitable code; often require significant upgrades.
How an ADU Project Typically Works
- Property Check (Fast, Early Insight)
Get a preliminary read on size, placement, access, and likely constraints.
CTA: Check Your Property - Feasibility Study (Site-Specific Detail)
Verify zoning, setbacks, utilities, access, and align the program with your goals.
CTA: Get a Free Quote - Design & Engineering
Create a plan that optimizes livability, privacy, and durability, then prepare permit-ready documents.
CTA: Design Your Own ADU - Permitting
Submit plans, respond to comments, and secure approvals. - Construction & Inspections
Build to code with a predictable schedule, then complete final inspections and move-in.
ADU FAQs (Quick Answers)
Do I need separate utility meters?
Not always. Some cities allow shared services with sub-metering. Feasibility will determine the best, compliant setup.
What size ADU can I build?
It depends on local standards (setbacks, height, lot coverage) and your site. Many lots can support studios to two-bedroom homes with the right design.
Can I convert my garage?
Yes—if upgraded to habitable code (foundation, structure, insulation, egress, energy, fire). “Light” conversions rarely pass.
Will an ADU increase my home’s value?
A legal, well-designed ADU typically improves functionality and market appeal, supporting long-term value.
How do I keep the project on time and budget?
Start with feasibility, use standardized plans where possible, finalize selections early, and work with an experienced ADU builder.
Bottom Line: Start with the Fundamentals
A successful ADU starts with clear feasibility, livable design, and code compliance. Nail those basics, and you’ll create a flexible, lasting asset for your family and your property.
Ready to Explore ADU Possibilities on Your Lot?
- Check Your Property – Quick, early insight for an ADU basics assessment.
- Get a Free Quote – Understand costs and timelines for your site.
- Design Your Own ADU – Explore layouts built for everyday living.
- Get in Touch – Talk with California ADU builder experts today.
