21 Things to Have in ADUs

white kitchen with wood and stone accents

There's so much an accessory dwelling unit can add to your property, so many possibilities to explore. There are at least 21 things to have in ADUs to make sure that you're getting the most out of them, and that they're completely legal, too.

What Is an ADU?

What is an ADU? An accessory dwelling unit is an independent dwelling unit located on the same property as a house, but not necessarily fully detached from the house. This may be called a "granny flat," an apartment, a studio space, or a converted garage, among other names.

AUDs can be detached or attached. You can also have a garage ADU or an above-garage ADU.

Some people even create basement AUDs. The accessory dwelling space can be anywhere on the property.

But if this independent space is going to be used as a place to live, no matter where it's located, there are many things the ADU must have and quite a few it should have. In order for an ADU to be an ADU, there are a lot of regulations, codes, and basic human needs you are required to meet.

12 Things You're Required to Have in ADUs

For an ADU to be legal and up to code, the unit must meet several regulations as set forth by the state where you live, as well as the county and possibly the city where you live as well. Multiple branches of your local government, including local housing boards and neighborhood associations, may impose regulations on you and your ADU.

To make sure your ADU is fully legal, you're going to need to make sure you meet all of these various codes and regulations.

Depending on where you live, specific regulations and requirements will definitely vary. However, you can assume that for the most part, your ADU will be required to have multiple elements that are considered to be necessary for basic human life.

ADU at night with string lights

1. Private Entrance

One requirement that is nearly universal for ADUs is the private entrance. The unit cannot be considered to be an independent dwelling space without this feature.

In some places, it is required that the entrance to the ADU be invisible from the street, and some places even require that it has its own private driveway.

2. Electricity

This one is pretty obvious. The ADU must absolutely have electricity in order to be a livable space.

In many places, the ADU power supply can come from the main house. You can have an electrician run a new power line out to the ADU from the main house and handle the whole matter fairly easily.

3. Fire Safety

Don't forget about fire safety, regulations for which are extremely regulated. Your ADU may be required to have sprinklers, and it may even be required to be within so many feet of a fire hydrant.

At the very least, your ADU will likely be required to have a smoke detector and even if it is not, install one.

4. Kitchen

While it's not always the same everywhere, it's pretty much standard that the kitchen of an ADU must have a sink with running water and a stove or hookups in place for a stove to be installed. Some places also require a certain amount of cabinet and counter space.

5. Bathroom

For the bathroom to be an acceptable bathroom, in most places, this space must contain a toilet, a sink, and a shower or a bathtub for washing. Some local governments may allow for ADUs to contain a half-bath.

However, this is not a comfortable living situation for anyone. Do whatever you can to install a shower, because it is a basic human need to bathe.

small bathroom with sink, toilet, and shower

6. Sleeping Area

A dedicated sleeping area is essential for any ADU, but you are not always bound by regulations to have this area be a certain size. In some ADUs, the sleeping area can be as simple as a convertible couch in the combined living/bedroom space.

Be sure to include a comfortable sleeping area in your ADU. To save space, you can always install this as a loft above the couch or as a small area separated by a curtain.

7. Permits

Make sure that you have all the necessary building permits and that your property is zoned for additional residents. If you don't have the proper building permits, you could end up paying heavy fines that add to your total cost.

8. Environmental Controls

The ADU must have its own environmental controls—some way to regulate temperature. You may achieve this with a small space heater or radiator to add warmth in winter and a small air conditioning unit to keep things cool in summer, or you may install an entire HVAC system, depending on what you want.

No matter what you choose, the ADU must have some means of providing heat and cold to those living inside.

9. Water

As for the water, it is perfectly okay if the ADU shares a water pipe (and water service) with the main house. This can make things a lot easier and more affordable when it comes to plumbing.

10. Sewage

The ADU must also have its own sewage line. This line can connect to the main sewer line of the house, but there must be a sewage drainage line from the ADU that carries waste away from the unit.

sewage pipe lines

11. Size Considerations

Some states, counties, and cities have very specific space requirements for ADUs. In California, for example, the bedroom and living area must be at least 70 square feet, while the kitchen must have at least 50 square feet of space and the bathroom, 30.

In other states, however, you need only ensure that your ADU reaches a certain size minimum. In New Hampshire, your ADU must meet an overall space of 750 square feet, and it doesn't matter how it's allocated inside the dwelling.

Typically, ADUs are between 800 and 1,000 square feet on average. However, this varies greatly.

12. Design

Some states have regulations regarding the overall design and look of ADUs, which may also be a requirement of certain neighborhoods as well. In some areas, the ADU must maintain design standards that are in keeping with that of the main house on the property.

9 Things That Are Good to Have in ADUs

While not required, there are some things that are simply a great idea to have in your ADU. Add these extras while you're working on the ADU, and you will be adding a whole lot of value and usability to this space.

1. Exhaust Fan

Though it's rarely required, an exhaust fan is a great thing to include in the bathroom. Exhaust fans are especially useful in small bathroom spaces, which often get very humid.

The exhaust fan is an effective way to get rid of moisture in the bathroom, which helps prevent the growth of mold and mildew. This is an important and popular extra feature that you should definitely try to add to your ADU.

hands touching small exhaust fan

2. Counter Space

While the law likely requires you to have a stove in the kitchen, most people aren't going to feel at home unless they also have a microwave. Try to remember that most people are going to want a microwave while you're thinking about counter space and planning the design.

3. Dishwasher

It's a very nice addition to include a dishwasher along with a kitchen sink, which is likely to be required. Dishwashers are made in pretty small sizes, so you can include a little one if necessary to add what many people consider to be a very basic kitchen amenity.

4. Hood

A stove hood may not always be required, but it's an excellent idea. Include this in the kitchen to make your ADU a much more comfortable living space and add an extra that really makes a huge difference.

5. Laundry Facilities

Though it will probably never be required of you to include laundry facilities by any sort of city or state regulation, it is a very nice bonus to add this if you can. You don't need a ton of space to include a small, stackable washer and dryer unit.

In fact, this can be tucked into a standard-size closet. In an ADU, this is truly a luxury feature that will be very much appreciated.

laundry machines in small room

6. Privacy

Consider the dwelling part of your ADU. You're most likely creating this unit so that it can be lived in and used, so don't forget to think about yourself, too.

You will need privacy from whoever is in the ADU, and they want privacy from you. Consider using landscaping, trees, or other additions in order to create privacy between the main home and the ADU.

7. Windows

Though it's strangely not included in many regulations and codes set forth by states and cities, windows are a pretty essential element for any dwelling space. Do whatever you can to include at least one window in the ADU and try to get a window in every separate room of the unit if possible.

People need natural light. Multiple studies have proven that sunlight is essential for both physical and mental health, and any living space is truly dreary without at least a small window to let in light.

8. Storage

Everyone needs a place to put their things. Don't get so caught up in creating rooms that you forget about storage and closets.

Not everything can be put into drawers, after all. Do what you can to integrate storage into your ADU.

Add closets, built-in shelves, overhead places to store items, and anything else you can think of and reasonably achieve to give your ADU as many storage spaces as possible. After all, no one ever said they wish they had less storage in the place where they were living.

9. Lighting

Technically, all you have to provide is electricity. And you know, people can buy lamps.

However, it is a nice touch, and it's much more convenient if you install lighting in the ADU. Overhead lighting, wall scones, add whatever makes sense for your space and your budget.

Lighting adds a nice homey touch to the space and makes it feel much more complete. This will give the ADU a much more finished look.

Things to Have in ADUs

There are lots of things you are required to have in an ADU and lots of things that you simply should have in your ADU. Add them all, and you will create a space that is comfortable and highly livable that adds a whole lot of value to your property.


small finished house

Can you rent out an ADU?

Many people choose to add an ADU to their property with the sole purpose of renting it out in order to make a little extra money, which can be a good use of this space. Some cities, counties, and states have regulations regarding how many non-related people may reside on a single property, so you want to check for ordinances like this before you take on any renters.

Otherwise, there is no reason that you cannot rent out your ADU in order to make some extra money. You can also consider using this space as a temporary rental, such as an Airbnb, in order to get a little income from your unit.

Can you add internet and cable to an ADU?

You can absolutely add internet and cable connections to your ADU if desired, and this can be a nice feature. People will likely want both these additions to any living space they may be using.

Call your local telecom company to ask about having new connections run from your existing residence to a new dwelling unit, and you can get more specific information about cost, the time it will take to complete the work, and any other questions you may have.

How much does it cost to create an ADU?

The cost of creating an ADU on your people varies greatly depending on whether the unit is being placed in an existing space or whether you're building something brand-new. Keep in mind that an extensive remodel can be as expensive as new construction, depending on the amount of work that needs to be done.

To figure out how much this project will cost, factor in the cost of all the plumbing fixtures, kitchen appliances, and lighting fixtures you need to buy. Don't forget the cost of utilities such as the heating and cooling system, the new water and sewer plumbing lines, the electrical connection and any other cable or internet connections, and the cost of a gas line, if needed.

Also factor in the cost of insulation, drywall, and other building materials, if you need these things. Include the cost of kitchen cabinets and counters, along with the bathroom vanity and bathroom tiles, along with tiles or flooring for the kitchen.

Will you need carpet, paint, and other finished materials? Include this as well.

When you add up the price of all these materials, fixtures, and appliances, you will still need to add extra money for permits, professional workers like plumbers and electricians, and even some extra money for unforeseen expenses that are certain to appear.

It is costly to create an ADU, but there are many good reasons why you might want to add this feature to your property. The additional value a good ADU can add to any property is worth the initial cost of creating the unit.

Further Reading

7 Small Bedroom Tips and Tricks

9 Hacks to Make Your Bedroom Feel Bigger

How to Maximize Space in Your Bathroom With a Corner Shower

Kitchen Design on a Budget

Kitchen Furniture for Small Spaces

Small Space Hacks