SB9 ADU

What is SB 9? This abbreviation stands for Senate Bill 9, also known as the Home Act. It’s a California law passed as a measure against the housing crisis. SB 9 allows for two types of action with single-family residential lots: two-unit development (converting a primary dwelling unit into a duplex) and splitting the lot into two adjacent parcels (each one must be at least 1,200 sq. ft). If you split your lot in two, you’ll be able to have four buildings on it — two ADUs and two primary units (your existing single-family home and a new house). The main purpose of this law is to promote the construction of additional housing units and thus mitigate the effects of the housing crisis.

In our article, we’ll take a close look at SB 9 and its main distinctive features and compare it with accessory dwelling unit (ADU) construction.

SB 9: The Main Requirements

SB 9 has several exceptions that can disqualify property owners from using it. Knowing these exceptions is essential for deciding whether the single-family lot split provision is a suitable variant for you or not.

They are the following:

• If your lot is in a high-risk area — for example, a territory with a high probability of fires, floods, earthquakes, or in a hazardous waste site, you can’t use SB 9. Additionally, this rule covers prime farmland, historic districts, rare species habitats, and conservation zones;
• In case you rent out the primary unit or did it in the last three years, you can’t demolish or modify it;
• The lot split has to be even or at least 40/60. You won’t be able to split your lot into a very big and a very small part;
• This law requires owner occupancy of your existing single-family home. You’ll need to reside on the same lot for at least 3 years since the splitting.

Because SB 9 is a rather new law and exists only in California, the financial institutions in many cities don’t have sufficient experience in dealing with split property. This means that, sadly, you may have some problems with lending.

SB 9 Owner Occupancy

As we’ve already said, the SB 9 lot split provision requires a three-year owner’s occupancy. It means that the property owner has to live in the existing single-family home for three years from the moment of approval. Moreover, the law forbids ministerial approval of property splits on neighboring parcels by the same individual. This measure is meant to avoid possible speculations.

In addition to that, you can’t use SB 9 if a tenant lives on your property now or lived there in the past 3 years. This measure prevents displacing or evicting tenants from rental units.

What You Can Construct on a Split Lot

If you start constructing a new primary dwelling unit on a lot created with SB 9, you’ll have to follow your local zoning rules. You’ll also need to do it if you’re turning your existing single-family home into a duplex — as long as those regulations don’t physically preclude two-unit developments. Moreover, if you want your lot splits to be eligible for optimization, you’ll need to construct a new unit there.

Also, it’s important to mention that many cities have parking requirements (such as constructing a garage). If you build an accessory dwelling unit (ADU), you can waive them, but in case of a main house, complying with them is necessary for completing the permitting process. Note that in many cities, those requirements change depending on the distance to the nearest major transit stop.

SB 9 and ADU: The Main Differences

You’re probably trying to choose between these two affordable housing options and don’t know which one is better for you.

To help you, we’ve compared both variants and their main characteristics:

1. Can you sell a unit separately? In the case of SB 9, yes, you can divide your lot into two parts that are sold separately. As for an ADU, it’s usually illegal to sell it without the primary residence (but you can use it as rental housing). However, a recent California state law gives local authorities the possibility to permit ADU sale without the primary dwelling unit;
2. Can you use it on a multi-family lot? Senate Bill 9 is only for single-family lots, so if you’ve got a multi-family one, you won’t be able to use it. On the other hand, accessory dwelling units are possible to build on such lots — you can construct one or two units in addition to your primary dwelling unit;
3. Is the owner’s occupancy necessary? For SB 9, yes — you’ll need to live in your primary dwelling unit for three years since the approval of the splitting. For an accessory dwelling unit, it’s not necessary at all;
4. Can you do it in a high-risk or historic area? Applying Senate Bill 9 is not possible there, but building additional housing units is (if property owners design them according to special regulations);
5. Can HOAs forbid SB 9 lot splits or an ADU construction? It can prohibit lot splitting but is not applicable to ADUs;
6. What about impact fees? For a split lot or a duplex, they’re standard, but in the case of accessory dwelling units less than 750 sq. ft, they’re smaller;
7. Is the utility metering separate? Various “right of way” works and separate metering of utilities are compulsory for a divided lot, but not for an ADU project.

Note that some of the aforementioned things can be really expensive — for example, making utility connections on lot splits. You’ll need to connect them to the sewer and water pipes, which is super costly. Owner’s occupancy and the possibility of units being sold separately are also very important factors, which you’ll definitely need to take into consideration.

SB 9 Projects: The Biggest Difficulties

Using Senate Bill 9 can be risky because there are no such precedents in the affordable housing sphere yet. This California state law is basically an uncharted field with very few cases, so it’s still unclear how this law will work. Because of this, there are lots of gray areas here, and we can’t exactly say what interpretation they will have. All of this can lead to unpleasant consequences such as prolonged approval periods, additional expenses, and juridical difficulties. So, if you decide to apply SB 9 on your lot, be careful and remember that it probably won’t be easy.

Other potential challenges for property owners include:

• Specific restrictions. To get local government approval for a lot split, your property must match certain local zoning regulations — for example, parking requirements and size limits of single-family homes. You’ll need to plan the splitting very carefully not only to obtain the permit but also to be able to carry out your later construction plans;
• Budget limitations. For an SB 9 lot split, you’ll need a considerable amount of money. As we’ve already said, things like utility metering for separate lots can be expensive. If you don’t plan your budget properly, there’ll be a high risk of unexpected expenses;
• Infrastructure and design difficulties. When planning out your new split lot, you’ll need to think very well about what you’ll place on it and how you’re going to develop it in the future. It will help you avoid many problems with its design, infrastructure, and logistics;
• Potential law implications. We’ve already noted that SB 9 requires three-year owner occupancy. In addition to that, it has several rental limitations. For example, you can’t apply SB 9 if there are rental units on the same lot. You’ll necessarily need to consider all of those aspects. We’d advise you to consult with a local agency specialist.

SB 9 and an ADU: The Compatibility

Is it possible to build additional housing units on split lots created with SB 9? Yes, if your local government allows it. So, in many cities homeowners can have two accessory dwelling units and a primary unit converted into a duplex on one half, and the same configuration on the other. However, this varies depending on the local zoning laws, so it’s crucial to read them thoroughly or consult with a specialist before planning.

Frequently Asked Questions — FAQ

What are ADU and SB 9?

SB 9 (Senate Bill 9) is a rather new local law which allows California homeowners to split their property lots into two parts, or to turn their houses and duplexes. The main purpose of this law is to stimulate growth of the affordable housing market. An ADU (accessory dwelling unit) is an additional, smaller house built on the same lot as the main residence.

There are different types of ADUs: attached, detached, a junior accessory dwelling unit, a garage or basement conversion, and so on. The ADU law varies greatly depending on the local jurisdiction. Typically, the maximum number of ADUs on the same lot in California can be two: one ADU is regular and the other is junior.

Which property qualifies for SB 9?

According to the state law, SB 9 eligibility requires two following things. Firstly, your lot has to be in a city area or agglomeration. It is a strictly urban lot split. Secondly, its location needs to be in a single-family residential area.

How much does an SB 9 lot split cost?

Usually, a lot is split, including county/city permit fees and third-party vendor expenses, which cost $50,000-$80,000. However, there may also be some additional expenses. For instance, different “right of way” improvements, such as utility connections, can significantly increase the overall price.

What is the maximum square footage for SB 9?

The biggest size of any building on a split lot is 850 sq.ft.; meanwhile, the smallest is 800 sq. ft. The total area of both primary dwelling units (single-family homes) on the parcel shouldn’t exceed 1,700 sq. ft. As for the lot parts themselves, the maximum square footage of each one is 1,200 sq. ft.