ADU (Accessory Dwelling Unit), shed, tiny home, backyard home, guest home - what is the difference?

ADU (Accessory Dwelling Unit), shed, tiny home, backyard home, guest home - what is the difference?

Introductory image showing different types of accessory structures: ADU, Tiny Home, Shed.

More and more Californians are choosing to add an accessory structure to their property to expand living space for themselves, their family or their friends. Sometimes it’s a backyard studio - a quiet place to work from. Sometimes - it’s an independent home for freshly graduated kids transitioning to the real world, or space for the elderly to be close to their family as they age in place. Some build an accessory structure for the sole purpose of increasing their home value.

Understanding the difference

Are you considering adding an ADU? Join the club! Tens of thousands of your fellow California residents are doing the same thing. From Long Beach to Lancaster, from Oakland to Orange County, homeowners are moving forward on their ADU projects thanks to recent legislation.

Find out which ADU types may be eligible on your property by using Housable’s free property check tool

Taking a step back - if you’re thinking of adding an accessory structure, it's crucial to understand the difference between structure types. Small details can go a long way in extending the process, so it makes sense to be precise about what you need the structure for and how you want to use it.

Doing your homework will save you from unnecessary stress and save money, but will also help you get the most of the precious space in your garden while reaping the many benefits an ADU has to offer, and it may even save you some money! In this article, we’re covering the addition of new and detached structures, and their types. If you are interested in converting an existing free-standing structure, or a part of your main residence - stay tuned, as we will cover this as well.

So why is it important to understand the difference? Recent legislation has opened the doors for all types of ADUs on most properties, meaning you could have many options to pick from! Some municipalities have more stringent restrictions than others, but in most cases, you may be allowed more than you think.

Of course, it is possible to build something small under the radar if no one will ever notice, but you really should consider the legality of your secondary structure - especially if you’d like to sell or otherwise legally improve your property in the future (an illegally constructed dwelling will not be considered as part of the total appraisal value).

Detached Accessory Structure Types

With those differentiators let’s dive into each accessory structure type and their particular attributes:

ADU (Accessory Dwelling Unit)

This is the official term for any type of additional (secondary) living unit or an apartment that you plan to add to your property in addition to your primary home.

ADUs are standalone, second units. They typically include a bathroom, bedroom(s) and kitchen facilities, in addition to living space. They require permitting, which is dictated by size, design restrictions and other local-zoning requirements.

Those rules differ from city to city and the best way to find them is by using Housable’s free property check tool. Find out which ADU types may be eligible on your property by using Housable’s free Enter your address and select it from the dropdown to see what an ADU might look like on your property. This information is not shared with third parties.

For example, if you wanted to see if a detached ADU of 1,000 square feet was allowed in your city, Malibu, or see if it fit in your backyard, you could use our tool to see both, free of charge.

Permitting is a critical step in the process. When you take the correct permitting steps, your new home will contribute to your property’s value because it is code-compliant, connected to utilities (city grid) and can be used or rented as a totally separate living unit, independent from the primary home. Taking the time to do your homework early will protect you from disasters later on. Housable makes it easy to get permitted, all without commitment.


A shed is the simplest and the fastest type of a structure that you can build in your backyard. Sheds usually don’t have utilities connected and they are meant for daily use, as a quiet studio to work from or a workshop. Maybe a place where you want to enjoy your coffee on a rainy day!

Sheds are an interesting option from a space perspective, but are generally not helpful if you want rental income or increased property values, since in many cases they are not permanent structures.

Since there are no utilities connected, it would be impractical to host anyone, even your close friends. In the case of selling your property, you need to check your local zoning - you may have to remove it if it is not a permitted structure (illegal). Another limit to sheds is their size. Typically anything above 200sf will require a permit. If you would like to have anything larger it will have to go through a review process. This is a case where it may make more sense to build an ADU instead with a more flexible use for renting short-term or long term for income.

Tiny Home

Tiny homes are a hot topic these days. This is an evolving, flexible term, and thus there is a lot of confusion about what a “Tiny Home” really is, and what you can do with it.

People commonly refer to them with the two basic meanings. They could be considered tiny because of the limited size and related to the trend of downsizing; or they could be considered tiny because they are mobile, have wheels, or not permanently attached to the ground in order to be easily moved around.

Tiny homes are cool, but they also can’t be connected to the city grid unless in designated areas (for example trailer parks). Tiny homes cannot be connected to residential utilities also because they are not inspected or built to sufficient building codes. Many of the conveniences afforded to Tiny Homes are also applicable to ADUs. Therefore, they are not a widely accepted housing solution in urban areas.

Los Angeles is a notable exception for Tiny Homes. At the end of 2019, the Los Angeles City Council passed regulation allowing anybody to add a mobile tiny home to their backyard, with allowances to connect to utilities, but with the popularity of ADUs becoming a more practical solutionm, it's unlikely future cities will adopt similar ordinances.

When it comes to size, tiny homes are a great opportunity to downsize because they have limited square footage. If you want to live comfortably in a tiny home, you will need spatial creativity and minimalist solutions. They often have decreased overhead space, foldable furniture, like tables, and transformative spaces (for example; transform your dining room into a bedroom by unfolding a bed that’s hidden in the wall). Some of those things are allowed in regular homes; the main difference remains the compact size of the home.

The tricky part of a tiny home is its mobility. Since it is mobile, it can’t be permitted as real property, and make utility connections (with exception in Los Angeles).

In most places, only homes permanently attached to the ground are allowed to be permitted. As a result in many cities, tiny homes are simply not allowed, due to their temporary nature and lack of compliance with building codes. They’re a good solution for off-the-grid living outside of cities, or in specifically designed locations with temporary utility connections like RV parks, but they are generally not seen as a solution to California's housing crisis. If you’d like to consider getting a tiny home in a city, and consequently going through the permitting process, you have to be careful where you get it from.

First - it has to be designed to meet your local zoning regulations. If it is factory made, it has to be inspected along the production cycle and issued a state or nationally approved insignia to certify code compliance. In other words - you can’t buy an off-the-shelf home and expect to install, permit and have it connected to the city grid.

If you’d like to buy a ready made tiny home and put it in your backyard in Riverside - the home has to be inspected during production for your local building code, specifically meeting Riverside local requirements.

If you’d like to work with an architect and a contractor to have your tiny home properly permitted and built, you can totally do so. You just have to remember that it has to be a permanent structure, in which case it will be as much a tiny home as it is an ADU. It will have to meet the same regulations as an ADU and thus carry the ADU price tag.

Backyard Home & Guest Home

Backyard home and guest home are typically synonymous with ADU. The difference in names comes from varied terms across states and cities, though ADU is starting to become the most standard term. Other popular names for ADUs are: laneway homes, carriage homes, granny flats, in-law suites, secondary units, etc… which usually appear as a result of previous or historical zoning codes. As you may guess, all of these fall into the same regulations as ADU in terms of size, location on site, design restrictions and parking spots.

Accessory Dwelling Unit called guest homes or backyard homes.

Comparing Accessory Dwelling Units (ADU), Tiny Homes, and Sheds

In this article we mentioned three different types of accessory structures: ADUs, backyard or guest homes which are permanent homes meant for full-time living; tiny mobile homes -great for living outside of the city grid and other- and sheds , or day-use only structures one can add to their backyard.

Accessory Dwelling Units (ADUs) are especially welcome in cities as they are directly chipping away at the growing housing disparity.

Are you interested in adding an ADU to your property? Find out whether you are eligible using Housable’s ADU free property check tool