What Is An ADU?

What does ADU Stand For?

Many people ask what is an ADU unit, but that's a slight redundancy— as “unit” is the last letter in ADU meaning “Accessory Dwelling Unit.” It doesn’t exactly roll off the tongue, and there are many terms for them (granny flat, in-law suite, backyard cottage, to name a few).

But what does ADU mean definitionally?

Simply put, it’s a structure built on residential land, separated in some way from the primary residence, and intended for long-term occupation by renters or relatives. ADUs must be smaller than the main home. They can be attached to the primary housing unit by a wall (i.e., converted garage, basement, loft) or built apart in the backyard.

All the facilities and amenities expected of a residence are contained in an ADU (kitchen, sleeping quarters, and restroom), meaning its occupants can live independently of the main dwelling.

There are many advantages to having an ADU on home property. Retirees can live out their golden years with peace of mind, knowing their family is just a short stroll away—but not so close that one might feel as though they were imposing upon the other.

ADU homes allow extended or inter-generational families to live together on one lot, one group in the main house and one in the ADU, meaning more privacy and space for everyone. Adult children can have a place to live while they study or work nearby without having to contend with a highly competitive rental market.

Alternatively, homeowners can earn a passive income by renting their ADUs to members of the community, providing a more affordable and convenient alternative to renters who might otherwise be subject to long work commutes from the periphery of town.

In this way, ADUs help maintain a more robust local economy by providing housing to local workers, reducing urban sprawl.

Types of ADUs

As with any other type of housing, accessory dwelling units can come in all shapes and sizes. ADU companies worth their salt will tailor their designs to the needs or specifications of the homeowner. It’s worth noting that each type has its advantages and disadvantages.

While many ADU types have their own naming conventions, they generally fall into three categories: internal, attached, and detached.

Attached ADUs are, as the name implies, physically attached to the primary dwelling and share an existing wall or foundation with the main building. This might include a space above a garage or a side addition to the house. Attached ADUs might be referred to as “granny flats” or “attached apartments,” depending on the expansion.

Internal ADUs are conversions of parts of a home into a dedicated living space (for example, a former garage, loft, or basement). Like an attached build, the naming conventions for internal ADUs depend on the conversion. For example, a converted basement might be referred to as a “basement suite.”

Detached ADUs are entirely divided from the house but are still within the boundary of the lot. One obvious advantage for homeowners with space on their lot to spare is that each occupant has more abundant privacy. Detached ADUs are sometimes called “guest houses,” “in-law suites,” “laneway cottages,” or “backyard cottages.”

Internal and attached accessory dwelling units come with their own advantages and disadvantages, and the same goes for detached ADU homes.

For those looking to implement ADU building on their property and currently considering each type, it’s worth remembering that the best ADU companies will assess the size and terrain of a lot and how well their ADU designs will blend with the main property from the street view.

While the wishes of the local homeowner association should be taken into consideration, homeowners with an abundance of space should still consider internal conversions or attached ADUs for reasons beyond aesthetics.

What Is A Junior ADU?

A Junior ADU is a small accessory dwelling unit.

What is a Junior Accessory Dwelling Unit?

While requirements differ depending on the jurisdiction, a JADU is generally attached or internal to the main residence and does not exceed 500 square feet in size. Additionally, unlike standard accessory dwelling units, JADUs are not required to house bathroom facilities.

Requirements and permits to get an ADU

As long as the structure is smaller than the primary residence, has an independent entrance, is on the same lot as the main residence, and has adequate space for bathing, sleeping, and cooking—and comes with the prerequisite facilities for each—it can be considered an ADU.

Since the government of California streamlined the process of obtaining permits for ADUs, they have become more and more popular with homeowners, especially in California, since 2018.

What Is An ADU In California?

All ADU types are permitted in the state of California, including internal, attached, detached, and junior ADUs. However, regulations for ADU designs can differ from each jurisdiction.

How Many ADUs Can You Have In California?

The number of ADUs allowed depends on the municipality. For example, in the county of San Diego, the owners of a lot with a single-family dwelling (or proposed single-family dwelling) are permitted to apply for the construction of one ADU and one junior ADU—two in total.

Owners of lots with multiple-family dwellings are a little different, and the requirements again differ depending on the jurisdiction. ADU San Diego County permits lots with multi-family dwellings to have a minimum of one or two ADUs, then one for every four dwellings (or up to 25% of existing multi-family living units).

Interested in building an ADU in San Diego?

If you're looking to have an ADU in your property don't miss the chance to work with the best ADU designers! NT Studio would guide you in the process from A to Z and design your ADU as you want to. Being experts in ADUs they'll help you choose the ADU type, design and ... that fits your needs. Get a quote today and start the best investment of your lifetime!

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