ADU Multifamily, California: Note for Multifamily Owners

During the surge of ADU construction, multifamily property owners were in a disadvantageous position before 2020 because their capabilities to build on their plots were very limited. Although the regulations evolve over time and more opportunities arise, not everyone is aware that they can add an accessory dwelling unit to their multifamily property.

Accessory dwelling units are secondary, independent structures built on the same parcel as the existing primary residence. An ADU is a livable space that you can use to expand your square footage, earn additional rental income, or increase the overall property value of your asset.

With A+ Construction & Remodeling in Sacramento, let’s explore how new laws and state building standards affect the possibility of building ADUs on multifamily dwelling properties.

Multifamily Property Definition

A multifamily property comprises two or more residential dwellings structurally connected to one another. This means that if you own some square footage in a duplex, a triplex, a quadplex, or even an apartment building, you can add multifamily ADUs to your property.

However, it’s important to note that if you have multiple primary residential units on the same lot but have no direct attachment or constructional connection, it is not a multifamily dwelling. Nevertheless, there’s probably a significant number of properties that fall under this notion in your region.

So, whether it’s a duplex or apartment building featuring several units under one roof, these all qualify as multifamily land. Now it’s time to discuss accessory dwelling units that you can build in the vicinity of the existing multi-family dwelling.

Additional Units for Multifamily Dwelling

You probably know that single-family homes can add at least one ADU as well as one junior ADU to their possessions. This is, of course, if the primary structure has a convenient location and both accessory dwelling units comply with the setback requirement.

Likewise, multifamily households may have multiple accessory dwelling units. The allowed number depends on the number of existing multifamily dwelling units in the following ways:

• Usually, local agencies allow multifamily owners to build two detached accessory dwelling units and one accessory dwelling unit converted from an existing structure (only non-livable).
• However, if you have a multifamily dwelling with more than eight existing units, you can add two detached 800-square-foot units and convert one ADU per each of the four units. This is especially convenient for apartment buildings if the existing space on the lot is enough for new construction.

Remember that you cannot transform living space into an accessory dwelling unit, but you can do this with attics, basements, garages, storage rooms, or boiler rooms. Besides, some areas let you have detached units united into one, separate only from the primary dwelling unit. However, others require them to be fully independent of each other.

Accessory Dwelling Unit Zoning Limitations

Zoning ADU regulations prescribe that even if you have a multifamily property, for you to add ADUs, it must occupy a residential zone. For example, if you live in a large apartment complex in an industrial or semi-industrial area, your multifamily structure still cannot have accessory dwelling units.

Accessory Dwelling Unit Size Limitations

The size limitations for multifamily properties align with the state regulations for ADUs constructed on any single-family property in Sacramento, California. Thus, city laws cannot restrict ADU size beyond the existing state law limit: a minimum of 850 sq. ft. for a single-sleeping room ADU and a minimum of 1000 sq. ft. for a two-bedroom ADU.

ADU Project Benefits

If you decide to add ADUs to existing multifamily dwelling structures, there are several ways it can impact your life. Accessory dwelling units open up such opportunities as:

• Abundant living spaces

A few square feet are never extra when it comes to life comfort. Like with single-family properties, you can allocate ADUs for work or hobbies if the room or privacy level in the primary residence is not enough. Whether you just need a small home for grown children so they can try out independence or a garden cottage for weekend guests, ADUs provide flexible living arrangements for all.

• Granny flats

An accessory dwelling unit can serve as a shelter for your aging loved ones if you live in a duplex. But your relatives need extra care; an ADU unit is a place where they can peacefully spend their days in a familiar environment surrounded by family members.

• Rental

An accessory structure in the same location as your existing multifamily dwelling can bring you stable cash flow from the property. If you rent out several units, a multifamily ADU can help you broaden your rental income sources, compensating for any possible idling of the primary units you rent.

• Property Resale

Although an ADU increases property taxes a little, it also increases property value. It’s impossible to sell an ADU without a primary dwelling unit, but when you do decide to sell your land, it leads to greater profitability over time. The more demand for housing grows, the more you will be able to make.

To sum up, an accessory dwelling unit comprises diverse uses, from fulfilling your own household needs to serving as a source of revenue (both rental and sale profit).

Accessory Dwelling Unit Types

The accessory dwelling unit types suitable for multifamily properties encompass many designs and layouts aimed at complementing the current configuration of residential structures.

The most widespread accessory dwelling unit types include the following:

• Attached ADU

Units built back to back with the primary residence are attached ADUs. They share a direct physical connection with the townhouse, triplex, or apartment building as they get integrated into their designs. Also, they may share some of the utilities with the main building.

• Detached ADU

Detached accessory dwelling units occupy the backyard or empty area on the lot distinct from the primary residence. Detached ADUs are self-sufficient, standalone structures that have their own utilities and that offer a higher level of autonomy.

• Garage Conversion ADU

Unlike new-construction ADUs, garage conversions utilize the unused space of your existing garage or other covered parking structure. This type of ADU allows for the transformation of something that no longer serves you into a useful asset that can potentially generate income.

• Basement accessory dwelling unit

Some homeowners can convert their basements, boiler rooms, or storage rooms into independent living spaces with amenities and a separate entrance. Even a few hundred sq.  ft. may become additional accommodation options on a property.

• Junior accessory dwelling unit

JADUs are smaller units that can only reach as much as 500 sq. ft. It is also not uncommon for them to complement existing multifamily dwellings because their smaller footprint allows them to boost housing capacity and optimize space.

All in all, local agencies typically permit all kinds of ADUs, from detached ADUs and attached ADUs to conversions and JADUs, to occupy multifamily properties. It’s only up to you which one to incorporate!

Frequently Asked Questions — FAQ

Is it hard to obtain ADU permits for multifamily ADUs in Sacramento, CA?

In order to obtain a building permit, homeowners have to make sure their unit complies with California state law as well as local ordinances. Also, there are certain factors that can delay the process or make it more complex, such as how thorough your building plan is or if you work with professionals or do it yourself. In any case, the process is manageable. It only requires attentiveness and patience.

What are the parking requirements for multifamily ADUs?

Such things as the availability of street parking and public transit, as well as your ADU size and number of primary units, can influence the parking requirement. Typically, if there is little to no street parking, public transit is far, your ADU is big, or there are many primary units, it may require parking. The exact number of parking spaces depends on the local jurisdiction.

What’s the difference between a new-construction ADU and an ADU transformed from an existing detached structure?

The difference lies in the cost and legal considerations. Thus, building from scratch entails higher expenses, from $350 to $450 per sq. ft., against $250 to $300 per sq. ft. in conversion. However, transformed units follow the same regulations as the original structure, while new constructions are not subject to some rent control rules.

What are the rear setbacks and height limits for multifamily ADUs?

The same as single-family ones, for multifamily ADUs, the rear and side setbacks must be a minimum of 4 feet from the property line. As for the height limit, multifamily ADUs typically cannot exceed 16 feet. But under specific circumstances, they can stand 18 feet tall or be two stories, especially if we speak about attached ADUs.

What is a good ADU size?

ADUs can be as small as 150 sq. ft. and as big as 1200 sq. ft. It depends on your goals, but an optimal ADU size is usually something around 750 sq. ft. This size allows for a comfortable lifestyle while remaining economical and seamless to integrate into the current lot.