In recent years, Accessory Dwelling Units (ADUs) have become a popular and valuable solution for homeowners looking to expand living space, create rental opportunities, or house family members. However, understanding the ADU ordinances and zoning changes that impact the development of these units is essential for homeowners planning to build one.
Local ordinances and zoning laws govern where and how you can build an ADU on your property, and these laws are continuously evolving. In this blog, we’ll dive into the latest ADU regulations, zoning changes, and what homeowners need to know to successfully navigate the process.

What Are ADU Ordinances and Zoning Changes?
ADU ordinances are rules or laws set by local governments that regulate the development of Accessory Dwelling Units (also known as granny flats, in-law units, or guest houses) on residential properties. These ordinances often define:
Where ADUs can be built: Local zoning laws determine whether your property is in a zone that permits the construction of ADUs.
ADU size limits: Local ordinances may set maximum size limits for ADUs, typically based on the size of your lot.
Setbacks and design guidelines: Zoning regulations can establish how far the ADU must be set back from property lines, as well as specific design standards that need to be met.
Parking requirements: Some ordinances may require a minimum number of parking spaces for an ADU, though this is being relaxed in many areas.
Utility connections: Local laws can also regulate how utilities like water, sewage, and electricity are connected to the ADU.
Why Are ADU Ordinances and Zoning Changes Important?
Understanding ADU ordinances and zoning changes is critical for anyone looking to build an ADU on their property. These regulations dictate:
Where You Can Build: Zoning laws specify the areas where ADUs are allowed. Some properties in residential or mixed-use zones may be eligible, while others may be restricted to multi-family units.
Design and Aesthetic Restrictions: Many jurisdictions enforce specific design criteria for ADUs, ensuring that the structure complements the existing home and neighborhood.
Cost and Feasibility: Local zoning laws and ordinances can affect the overall cost and feasibility of your ADU project. For example, if parking or utility requirements are strict, your construction costs may increase.
Permitting Process: Zoning and ordinances set the process for applying for an ADU permit, which can involve submitting plans, paying fees, and waiting for approval.
Compliance: Failing to comply with zoning laws and ordinances can result in delays, fines, or even forced removal of your ADU if it's built without proper approval.
Key Changes in ADU Ordinances and Zoning Laws
In recent years, local governments, particularly in California, have made several zoning changes and ordinance updates to promote the construction of ADUs. Some of the key changes include:
1. Relaxed Setback Requirements
Historically, ADUs were subject to strict setback requirements, which often limited where they could be placed on the property. However, recent zoning changes have relaxed these setbacks, especially for detached ADUs, allowing homeowners more flexibility in positioning the unit on their lot.
2. Increased ADU Size Limits
Many jurisdictions have increased the maximum allowable size for ADUs. For example, California’s recent legislation allows detached ADUs to be as large as 1,200 square feet, depending on the property size. Some areas have also expanded the definition of attached ADUs and junior ADUs to include larger units.
3. No Parking Requirement in Some Areas
In many urban areas and those close to public transportation, parking requirements for ADUs have been waived or reduced. Previously, homeowners were required to provide one or more off-street parking spaces for each ADU, but this is no longer a strict rule in many cities.
4. Eased Utility Connection Rules
Older zoning laws often required separate utility connections for each ADU, which could be costly. Recent changes have made it easier to connect ADUs to existing sewer, water, and electrical lines, reducing the overall cost of the project.
5. Streamlined Approval Process
Many local governments have streamlined the ADU approval process, providing faster permit approvals and reducing bureaucratic hurdles. In some cities, homeowners can even apply for permits online.
6. ADU Allowances in More Zoning Districts
Previously, ADUs were only allowed in single-family zoning districts, but recent zoning changes in many cities have expanded eligibility to multi-family and mixed-use zones. This makes it easier for property owners in urban areas to add ADUs and create more housing options.
How to Navigate ADU Ordinances and Zoning Changes
Here’s how homeowners can effectively navigate ADU ordinances and zoning changes in their area:
Consult Your Local Zoning Codes: Before starting your ADU project, check with your local planning department to ensure your property is zoned for ADUs and find out about any specific ordinances that apply.
Review ADU Guidelines: Every city has its own set of rules regarding ADU size, setbacks, and other requirements. Familiarize yourself with these rules to ensure your plans meet the necessary criteria.
Work with an Architect: A licensed architect or designer can help you create plans that comply with local zoning laws and ordinances, making the permit approval process easier.
Stay Updated on New Legislation: Zoning laws and ADU ordinances are frequently updated. Keep an eye on local news or consult with a zoning expert to stay informed about changes that might affect your ADU project.