ADU in Real Estate

It is any home that has an additional self-contained living space on the property. The terms for ADUs vary widely from location to location, and by type of ADU.

In law suite image

In-law suite

An in-law suite is a separate dwelling space in your primary residence or on your property. They’re sometimes referred to as granny flats or secondary units. Generally, people build in-law suites to allow their aging parents or in-laws to live with them while still ensuring a private place to retreat to.

You could build an in-law suite by extending or renovating your loft or basement, or upgrading an unused garage or shed. If you have enough space on your land, you could even build a structure from scratch, often known as a granny pod.

In law apartment

In-law apartment

When your in-laws come to visit, where did they stay? If they came to live with you, would they enjoy living in that same space? For most homeowners, the answer is no.

Which is where a mother-in-law apartment comes into the picture. But what is a mother-law-apartment? Also called an accessory dwelling unit (ADU), in-law suite or granny flat, these are living quarters where in-laws can reside when they move in with their children.

These apartments include a bedroom, bathroom, living space, and kitchen. What sets them apart from a typical suite is that they have a separate entrance from the main home and are not just additions, they’re fully functional houses.

They can be attached to the main house, converted from a garage, or (most commonly) a detached structure.

An in-law suite is ideal for a living situation in which an older adult would move in with their children but also wants to maintain their independence.

Granny unit

Granny unit

"A granny flat is a small house built on an existing property. It has its own entrance, kitchen, bathroom and living space."

Granny flats—now commonly called accessory dwelling units, or ADUs—are the answer to more room for family members or more income from renting the unit.

Granny flats range in size from about 250 to 1200 square feet. They can take many forms and be attached to the primary dwelling or detached from it, but they must have their own entrance, kitchen, bathroom and living space. While granny flats can be new stand-alone homes, they are often converted from a space that once was a garage, basement or attic.

With California’s 2020 passage of AB 68 and a host of supportive legislature, almost anyone who owns a single-family home in that state must be allowed to build one ADU of at least 800 square feet, as well as a junior accessory dwelling unit (JADU). If you own a duplex or other multi-family housing, you can build two ADUs on the property!

In 2021 California passed another bill, SB9, that will allow even more small homes to be built on single-family properties. As the kinks are getting worked out of that bill, granny flats are the most reliable way to increase housing now.

Carriage house

Carriage house

A carriage house (also called a coach house or a cart shed) is an outbuilding near a larger home that was initially built to store horse-drawn carriages and sometimes housed the coachman or caretaker on the upper floor. In contemporary society, homeowners often repurpose these buildings into small second homes or garage apartments (zoned as “accessory dwelling units,” or ADUs), tiny houses, guest houses, detached garages, home offices, studio spaces, or in-law suites.

The term “carriage house” can also refer to a small outbuilding designed and built in the style of authentic carriage houses. The terms “carriage house” and “carriage home” are sometimes used interchangeably, but the latter is a marketing term used to describe small single-family homes built on small lots that usually share walls with neighboring homes, similar to a townhouse or condo.

Tiny home image

Tiny home

Tiny houses usually have a kitchen, a bathroom, some sort of living space, and a lofted bed. Most people need to hook up to a utilities outlet to have electricity, but there are also self-sustainable houses. Taking advantage of renewable resources like solar power, tiny homes are living up to the expectation of going green.

First of all, it is small. Though this seems obvious, it's something you need to truly think about. If you have a spouse, kids, or even pets, things can begin to get crowded rather quickly. You don't have a space to be alone. There is nowhere to escape. Be sure that you can handle living in close quarters for extended periods of time before you jump into this purchase.

Next, you might not have a real toilet. Since it's difficult to have a water tank in a tiny house, most toilets are compost based. So you will need to dump your toilet every few days for liquids and every three weeks for solids.

Land is another issue. Many cities have building codes of which you must adhere. Sometimes, tiny houses aren't big enough to pass housing standards and you won't be allowed to build your house. So before you build, check your city requirements.

Tiny houses have received a lot of hype with reality TV shows spotlighting their minimalistic charm. If you are looking for a compact space with a fairly small price tag, consider looking into a tiny home.

casita image


Casita means cottage in Spanish. More formally, a Casita by definition is a small self-contained dwelling, typically unattached from a main home, but on the same property.

Casitas have a lot in common with mother-in-law suites. Usually, a Casita is built as a guest house, if not a permanent residence, for elderly parents so they can be close to their children and grandchildren.

Some homeowners, though, use their Casita more flexibly. They may rotate different relatives for long-term visits throughout the year. Alternatively, they might also use it as a short- or long-term rental unit, a transitional space for older children, or a studio or home office.