Introduction
In the last decade, California has faced a huge shortage of housing. To deal with this problem, the state has implemented rules for Accessory Dwelling Unit (ADU) - which are also known as Granny Flats, Backyard Homes or in-suits. These small houses soon became popular as they provide income opportunities from additional living space and rent. But there has been a lot of change in laws in the last few years.
If you are planning to create ADU, you must be wondering: What is the difference between new ADU laws and old laws of California? This blog explains it in simple words, so that you can understand how these changes affect home owners, landlords and tenants.
What Are ADUs?
Accessory Dwelling Unit (ADU) is a small, independent residential unit built on a plot similar to a single-family or multi-family house. ADU can be of the following types:
- Detached (a small unit in the backyard)
- Attached (connected to the main home)
- Garage conversions (turning an old garage into living space)
- Junior ADUs (smaller units within the main house)
Old ADU Laws in California
Before 2016, building an ADU in California was complicated. Here’s what homeowners faced under the old rules:
- Strict Parking Rules – Most cities required homeowners to add extra parking for every new ADU, which was difficult for small lots.
- Long Approval Process – Getting permits often took months or even years because local governments had strict zoning laws.
- Large Minimum Lot Size – In many cities, ADU was allowed only on large properties, making it impossible for the average landlords.
- Utility Fees – The builders had to pay a high connection fee for water, electricity and sewer, which increased the total cost.
- HOA Restrictions – Homeowner associations often blocked ADU projects.
As a result, very few ADUs were created.
Latest California ADU Laws (2020–2025 Updates)
California lawmakers realized the housing crisis needed urgent action. Since 2020, the state passed several new ADU-friendly laws to make the process easier.
Key Updates in the Latest ADU Laws:
- Faster Permit Approval – Cities must now approve or deny ADU permits within 60 days.
- No Minimum Lot Size – ADUs are allowed on almost any residential lot, regardless of size.
- Reduced Parking Requirements – If your home is near public transit, you don’t need to add extra parking for your ADU.
- Lower Utility Fees – Cities can’t charge high utility hookup fees for smaller ADUs.
- HOAs Can’t Block ADUs – Homeowner associations must allow ADUs if they follow state law.
- Multi-Family ADUs – Property owners with duplex or apartment buildings can now add several ADUs to the same plot.
- Height and Size Flexibility – Depending on the location, homeowners can manufacture 16–18 feet high-storey ADU.
- Junior ADUs Legalized – You can now build a JADU (Junior ADU) inside your main home, with its own entrance and small kitchen.
Comparing Old vs. New ADU Laws
Category | Old ADU Laws | Latest ADU Laws (2020–2025) |
Permit Approval Time | Took months or years | Must be approved in 60 days |
Lot Size Requirement | Large lots only | No minimum lot size |
Parking Rules | Extra parking required | No parking if near transit |
Utility Hookup Fees | High fees | Lower or waived for small units |
HOA Restrictions | Could block ADUs | Cannot block if laws are followed |
Number of ADUs Allowed | One ADU only | Multiple ADUs allowed on multi-family lots |
Junior ADUs (JADUs) | Not allowed | Allowed inside single-family homes |
Why These Changes Matter
These updates make it easier and cheaper for Californians to build ADUs. That means:
- More affordable housing for renters
- Extra income for homeowners through renting
- Flexible living options for families (guest houses, in-law suites, or housing for adult children)
- Higher property values
General Questions About ADU Laws
1. What are the minimum requirements for ADU in California?
- A separate entrance from the main home
- Basic kitchen facilities
- A bathroom (toilet, sink, shower/tub)
- Must meet local safety and building codes
2. What is the cheapest option for an ADU?
The most affordable options are:
- Garage conversions (turning an old garage into an ADU)
- Prefab or modular ADUs (factory-built units delivered to your property)
- Junior ADUs (JADUs) inside your main house
3. Can I build an ADU on my rental property?
Yes, landlords can build ADUs on rental properties. In fact, multi-family rental owners can add multiple ADUs, which means more rental income.
Should You Build an ADU Now or Wait?
With the latest ADU laws, now is one of the best times to build. Construction costs may rise in the future, and California may tighten rules again if there is overcrowding. Acting early helps you lock in today’s benefits.
Conclusion
There is a difference of land-sky between the old ADU laws and the latest ADU rules of California. Previously, making ADU was expensive, slow and often impossible. Now, the process is faster, cheaper, and open to nearly all homeowners.
If you’ve been thinking about adding an ADU, this may be your best chance. Not only can it give you rental income, but it also helps California fight the housing crisis.
