ADU RESEARCH BLOG
Useful answers for real ADU decisions.
Explore focused articles about costs, California rules, financing, permits, construction choices, rental analysis, and floor plans—each with a concise answer, a comparison table, a checklist, and primary sources.
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Ten focused articles. No vague answers.
These articles answer common questions about planning an ADU. Cost articles identify their published sources and model assumptions, regulatory articles link to official agencies, and every page identifies assumptions that still require local verification.
01California ADU Laws 2026
A homeowner-focused overview of California ADU laws in 2026, including the state framework, local review, property checks, permits, and official sources.
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02ADU Cost per Square Foot
Compare published San Diego ADU costs with transparent calculator examples. Understand construction-only vs. project budgets, exclusions and cost per square foot.
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03500 Sq Ft ADU Cost
Build an early 500 sq ft ADU budget with transparent examples for detached, attached, garage-conversion, and prefab approaches.
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04800 Sq Ft ADU Cost
Compare transparent 800 sq ft ADU cost scenarios, planning ranges, scope assumptions, and budget checks before requesting local bids.
Read the article05ADU Financing Options
Compare common ADU financing options, including cash, HELOCs, renovation loans, construction loans, and refinancing, with official lender resources.
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06California ADU Permit Timeline
Understand the difference between California ADU plan-review timelines and the complete project schedule, from feasibility through final inspection.
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07Garage Conversion vs Detached ADU
Compare a garage conversion and detached ADU by cost, privacy, existing-condition risk, design flexibility, utilities, and long-term use.
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08Prefab vs Stick-Built ADU
Compare prefab and site-built ADUs by total installed cost, design flexibility, schedule, access, permits, quality control, and contract responsibility.
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09ADU Rental Income Calculation
Estimate ADU rental income with a transparent worksheet for market rent, vacancy, operating costs, reserves, financing, and local rental rules.
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10ADU Floor Plan Checklist
Use this 15-question ADU floor plan checklist to test layout, storage, privacy, accessibility, furniture, utilities, daylight, and long-term flexibility.
Read the articlePublished by ADU.app · Updated September 26, 2026
ABOUT THE NUMBERS
See the assumptions behind every cost example.
Each article identifies its sources and model version. The California cost-per-square-foot comparison includes published builder examples and current v2.1 scenarios; older comparisons retain archived v1.1 assumptions. Model estimates are not contractor quotes.