Recent Updates in Accessory Dwelling Unit (ADU) Legislation

Table of Contents

1. Introduction

2. Key Legislative Changes by State

2.1 California

2.2 Colorado

2.3 Massachusetts

2.4 Washington (Seattle)

3. Benefits of Recent ADU Legislation

4. FAQ

5. Conclusion

Introduction

Accessory Dwelling Units (ADUs), often referred to as granny flats or backyard cottages, have become a pivotal solution to the housing affordability crisis in many U.S. cities. Recent legislative updates in 2024 and 2025 have significantly altered the landscape for ADU development, making it more accessible and streamlined for homeowners. These changes include faster and simplified ADU permit processes, enabling more homeowners to add secondary units to their properties with reduced bureaucratic hurdles and clearer regulatory guidance.

Key Legislative Changes by State

California

Owner-Occupancy Requirement Eliminated: Assembly Bill (AB) 976 has permanently removed the owner-occupancy requirement for ADUs, allowing homeowners to rent out both the primary residence and the ADU without residing on the property.
Relaxed Setback and Size Regulations: New laws have reduced setback requirements to as little as four feet and increased the maximum allowable size of ADUs to 1,200 square feet, facilitating more flexible construction options.
Condominium Conversion Allowed: Cities like San Francisco are exploring legislation to permit newly built ADUs to be sold as condominiums, providing homeowners with additional financial opportunities.

Colorado

Statewide ADU Promotion: Governor Jared Polis has enacted laws to encourage ADU development by easing local restrictions, including eliminating certain safety requirements and promoting factory-built homes.
Financial Incentives:A $5 million grant program has been introduced to assist low- and moderate-income residents in constructing ADUs, covering pre-construction costs and offering down payment assistance.

Massachusetts

Statewide ADU Permitting: The Affordable Homes Act, signed into law in August 2024, allows the construction of ADUs up to 900 square feet by-right in single-family zoning districts, simplifying the approval process.
Elimination of Owner-Occupancy Requirement: The new legislation prohibits municipalities from imposing owner-occupancy requirements on ADUs, enhancing rental flexibility for property owners.

Washington (Seattle)

Increased ADU Flexibility: Seattle's updated legislation permits the construction of two ADUs per lot, including two detached units, and increases the maximum size to 1,500 square feet, accommodating larger families.
Streamlined Permitting Process: The city has simplified the permitting process and removed street improvement requirements, reducing costs and encouraging ADU development.

Check How to Get an ADU Permit in Los Angeles

Benefits of Recent ADU Legislation

Increased Housing Supply: By simplifying regulations, more homeowners are incentivized to build ADUs, contributing to the overall housing stock.
Affordable Housing Options: ADUs provide more affordable rental options, particularly in high-demand urban areas.
Financial Opportunities for Homeowners: The ability to rent out ADUs or sell them as condominiums offers homeowners additional income streams.
Support for Multigenerational Living: Larger ADUs accommodate multigenerational families, promoting family cohesion and support.

Learn more about California's New ADU Laws

FAQ

What is an Accessory Dwelling Unit (ADU)?

An ADU is a secondary housing unit located on the same lot as a primary residence. It can be a detached unit, a converted garage, or a basement apartment.

Do I need to live on the property to rent out my ADU?

Recent legislation in several states, including California and Massachusetts, has removed the owner-occupancy requirement, allowing homeowners to rent out both the primary residence and the ADU.

Are there financial incentives available for building an ADU?

Yes, states like Colorado and California offer grant programs and financial assistance to help with the costs of constructing ADUs, particularly for low- and moderate-income homeowners.

Can I sell my ADU as a separate unit?

Some cities, such as San Francisco, are considering legislation to allow newly built ADUs to be sold as condominiums, providing homeowners with additional financial opportunities.

Are there size limitations for ADUs?

Size limitations vary by state. For instance, California allows ADUs up to 1,200 square feet, while Massachusetts permits units up to 900 square feet.

Conclusion

The recent updates in ADU legislation across various states have significantly transformed the landscape of housing development.These changes not only facilitate the construction of more ADUs but also provide homeowners with greater flexibility and financial opportunities.As these legislative trends continue, ADUs are poised to play a crucial role in addressing housing shortages and affordability issues nationwide.

Check How to Get an ADU Permit in San Diego