As the popularity of work from home continues to grow, so does the demand for living units such as a detached ADU, guest homes, or tiny homes.

Whether you’re a content marketer looking for the possibility of working from home, or a homeowner wanting rental income and increased home value, you’re probably exploring different alternatives right now.

So what’s the difference between an ADU vs a guest house? And what are the benefits and drawbacks of these real estate?

I’ll discuss both types of housing units, review common ADU laws on the West Coast cities and explore what you need to know.

So let’s dive right in – it’s time to find out which option works best for your needs!

What is an ADU?


An accessory dwelling unit (ADU) is a secondary living area on a property that can be used for additional space to your primary residence.

ADUs are typically smaller than the main house and have their own entrance and sometimes even bathroom facilities.

The proper definition of an ADU

An ADU is an independent living space that can be attached to or detached from the main residence on the same lot.

It must have its own separate entrance and all necessary amenities like plumbing, electricity, heating/cooling systems etc., to function as an independent dwelling unit.

There are also three types of ADUs to consider – attached, detached, and converted garage units.

Attached units may include additions built onto existing homes or apartments above garages; while detached units may consist of tiny houses or cottages located behind the main home.

Converted garage units involve converting an existing attached garage into livable spaces with basic amenities such as plumbing and electrical wiring already in place.

A major benefit of having an ADU is the potential for extra income through renting out this additional living space, either short-term or long-term depending on local regulations.

Additionally, it provides more room for family members who need their own private area without taking up too much space in your home itself; perfect for aging parents or adult children looking to move back home after college.

And if you want to increase property value by adding another habitable structure to your lot which could potentially increase resale value if you ever decide to sell down the line.


ADUs are a great way to add extra living space and income potential to your property.

They can be attached, detached, or converted from existing garages and come with their own separate entrance, kitchen, bathroom, and bedroom.

ADUs can also increase the value of your property by adding another habitable structure.

What is a Guest House?

Guest house

Guest houses are a great way to add extra living space and income potential to your property.

A guest house is a separate building on the same lot as your primary residence, typically used for short-term lodging purposes, similar to a hotel experience.

The proper definition of a Guest House

A guest house is a detached structure from the main home that can be used for additional short term living space, such as an office, in-law suite, or rental unit (no permanent residency).

Guest houses can range in size from small studios to large multi-bedroom homes depending on the needs of the owner.

There are several types of guest houses available including prefabricated structures, modular units, tiny homes, converted garages or sheds and custom built homes.

Prefabricated structures are usually made out of metal frames with insulated walls and roofs while modular units come ready to assemble with all components included in one package.

Tiny homes provide an option for those looking for more affordable housing options.  

Custom built homes give you complete control over how you want your guest house designed but will require more time, money, and headaches upfront compared to other options mentioned above.


Guest houses provide extra living space and potential income for property owners. There are several types of guest houses available, ranging from:

  • Prefabricated Structures
  • Modular Units
  • Tiny Homes
  • Converted Garages or Sheds
  • Custom Built Homes

Comparing ADU vs Guest House

ADUs and guest houses are two popular options for those looking to add extra living space or income potential to their property.

Both offer a range of benefits, but there are some key differences that should be considered before making a decision.

Cost Comparison

When it comes to prefabricated ADUs at least, they tend to cost way less than both regular ADU’s and guest houses alike, due to the fact that they don’t require as much construction work.

If you’re building an ADU through the means of using existing structures on the property to convert them to permanent dwelling units, then that may also be cheaper.

Guest houses, on the other hand, can involve more extensive building costs and building permits since they may need separate foundations and plumbing systems from the main house.

Space Comparison

ADUs generally have smaller footprints than guest houses, making them ideal for properties with limited space and are ideal to set up as a backyard cottage.

They also tend to have fewer amenities such as kitchens or bathrooms compared to guest houses which may include multiple bedrooms and full kitchens and bathrooms.

Legal Considerations

Depending on where you live, there may be different state laws governing what type of structure can be built in your area when it comes to an ADU vs a guest house.

For example, some cities allow only detached structures while others permit attached units like granny flats or garage conversions into livable spaces.

It’s important to check local zoning regulations before starting any project so you know exactly what is allowed in your area.

But with careful planning and research one can find the perfect solution for adding extra living space or income potential without breaking the bank.

What about Prefabricated ADUs?

Prefabricated accessory dwelling units (ADUs) are becoming increasingly popular due to their convenience and affordability compared to traditional construction methods.

Prefabricated ADUs are factory-built, modular homes that can be delivered and installed onsite in a fraction of the time it would take for a conventional build.

One of the biggest advantages of prefabricated ADUs is cost savings.

Because they are factory-built, they require less labor costs than traditional builds, resulting in lower overall costs.

Additionally, because they arrive pre-assembled from the factory, installation times are significantly shorter than with regular builds – sometimes as little as two weeks!

This means you can have your new space up and running faster than ever before.

Prefabricated homes also come with warranties from the manufacturer which provide peace of mind knowing that any issues will be taken care of quickly if something goes wrong down the line.

Advantages and Disadvantages of an ADU vs Guest House

Both have advantages and disadvantages that should be taken into consideration before making a decision.

Pros and Cons of an ADU

The main advantage of an ADU is that it can provide additional income through rental opportunities, while still providing you with privacy from tenants.

You also need to consider local zoning laws that may limit where you can build an ADU or how large it can be.

Pros and Cons of a Guest House

A guest house is similar to an ADU in that it provides additional living space on the same property as your primary residence, but only for short term stays.

And renting out a guest house isn’t always allowed by local zoning laws which could limit its potential income-generating capabilities.

Ultimately, the choice between whether you want to build either type of housing depends on what your needs are at the time.

Common ADU Laws in West Coast Cities

The laws governing ADUs in West Coast cities like California vary greatly.

Los Angeles

In Los Angeles, ADUs are allowed on lots with single-family homes and duplexes as long as they meet certain requirements.

The maximum size of an ADU is 1,200 square feet and the unit must be built at least three feet away from any property line.

Read more about the laws in LA at the official LADBS website.

San Francisco

In San Francisco, ADUs are allowed but there are some restrictions that apply to their construction.

For example, only one additional dwelling unit may be constructed per lot regardless of size or zoning designation.

If a lot has been divided into multiple dwelling units then these are the rules:

4 or less units = 1 ADU is allowed

5 or more units = No ADU restrictions

Additionally, all new construction must comply with existing building codes and height limits established by local ordinances in order to receive approval from the Planning Department.

Adu vs Guest House FAQs

What qualifies as a guest house?

A guest house is a type of accommodation that offers short-term lodging for travelers, typically in the form of private rooms or self-contained units.

Guest houses often provide amenities like bathrooms, making them an ideal choice for those looking to stay somewhere comfortable while still having access to their own space.

What are the disadvantages of an ADU?

ADUs (Accessory Dwelling Units) can be a great way to add additional living space to an existing property.

But depending on the size of the unit, it may not provide enough extra space for larger groups of people.

What do you call a guest house in Arizona?

A guest house in Arizona is commonly referred to as a casita.

Casitas are typically small, detached dwellings that offer additional living space for visitors or family members.

Wrap Up

In conclusion, ADUs and guest houses are both great options for adding extra living space to your home.

Both offer their own advantages and disadvantages depending on your needs.

If you’re considering either an ADU or a guest house, make sure to research the common laws in West Coast cities so that you can be sure of what is allowed in your area.

No matter which option you choose, adu vs guest house will provide additional living space that can help improve the quality of life for everyone involved!