The Dwelling Index
The Dwelling IndexResearch
Independent Research Initiative

ADU Research
& Housing Data

Independent, data-driven research on accessory dwelling units. Policy analysis, construction economics, financing markets, and housing supply impact.

ADU Statistics & DataOur Methodology
Built for:JournalistsPolicymakersUrban PlannersResearchersHousing Professionals

50+

Data Sources

All 50

U.S. States

2026

Current Data

Open

Methodology

Publications

Research & Data

Government-sourced data, original analysis, and citable statistics. Every number links to its original source.

Data Report

ADU Statistics & Data (2026)

Permits, costs, laws, and trends. Government-sourced data aggregated for citation. The definitive ADU statistics reference page.

State Data

California ADU Permits by City

ADU permit data for every California jurisdiction. Sourced from HCD Annual Progress Reports. Permits filed, issued, and completed from 2018 to present.

Cost Comparison

ADU vs. Assisted Living Cost by State

State-by-state breakeven analysis comparing ADU construction costs to annual assisted living costs. The cross-industry data hook.

Focus Areas

Research Domains

Six core domains spanning the full ADU lifecycle — from policy environment to financial outcome.

Data

Construction Cost Data

National and regional ADU construction cost benchmarks, cost-per-square-foot analysis by build type, and annual trend tracking.

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Policy

Policy & Zoning Reform

Analysis of state and local ADU zoning reform outcomes, pre/post implementation housing supply data, and policy recommendation frameworks.

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Finance

Financing & Equity

Home equity product analysis, ADU-specific lending gap research, renovation financing market sizing, and consumer protection review.

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Housing

Housing Supply Impact

Quantitative analysis of ADU contribution to housing supply, density effects, neighborhood valuation studies, and affordability metrics.

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Markets

Market & Permitting Data

ADU permit volume tracking by jurisdiction, approval timeline analysis, fee structure comparisons, and regulatory friction indices.

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Income

Rental & Income Analysis

ADU rental yield studies by metro area, occupancy rate analysis, short-term vs long-term income comparisons, and ROI modeling.

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Publication Types

What We Publish

Every publication follows our open methodology standard and is designed for citation, reference, and policy application.

Research Briefs

Focused, 2,000-5,000-word analyses of specific ADU topics with cited data and clear methodology.

Data Reports

Quantitative publications with original datasets, visualizations, and downloadable tables.

Policy Analysis

Pre/post analysis of zoning reform, permit streamlining, and regulatory change impact on ADU production.

Market Snapshots

Quarterly updates on ADU construction costs, permit volumes, financing trends, and rental market data.

Standards

Research
Methodology

Our credibility depends on methodological rigor. Every publication follows these standards without exception.

All research published under the Dwelling Index Research imprint adheres to our public methodology framework. We disclose data sources, analytical methods, sample limitations, and potential conflicts of interest for every publication.

Full methodology documentation available with each publication.

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Primary Sources Only

Government datasets, regulatory filings, lender documentation, and direct-survey data. No aggregator citations.

Reproducible Analysis

Published methodologies, disclosed sample sizes, stated confidence intervals, and version-controlled data pipelines.

Independent Editorial

Research funding, if any, is disclosed. Findings are published regardless of outcome. No sponsor review or approval.

Peer-Reviewed When Possible

External subject-matter review for major publications. Correction policy published and followed.

Audience

Built for Citation

Structured for the people who shape housing policy, inform public understanding, and make investment decisions.

Journalists & Media

  • Citable data points with source attribution
  • One-click stat & citation copy buttons
  • Pre-formatted suggested citations (APA, Chicago, Plain)
  • Press-ready charts and visualizations

Policymakers & Planners

  • Before/after analysis of zoning reform outcomes
  • Comparative policy frameworks across jurisdictions
  • Housing supply impact quantification
  • Regulatory cost-benefit breakdowns

Researchers & Academics

  • Disclosed methodology and data sources
  • Downloadable datasets (CSV and JSON)
  • Clear limitations and scope statements
  • CC BY 4.0 license for citation and redistribution

Research Updates

New publications, data releases, and policy briefs delivered to your inbox. No marketing — just research.

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