Are You New to Building an Accessory Dwelling Unit (ADU)? Here’s Everything You Need to Know

Are you new to building an Accessory Dwelling Unit (ADU)? Are you just looking for a refresher on what it is? Are you wondering if your property will qualify for one? ADUs are a great way to create affordable housing, increase the value of your property, or have rental income. Here’s Everything You Need to Know:


What is an ADU?

An Accessory Dwelling Unit, or ADU is a type of dwelling unit that either has its kitchen and bathroom facilities or shares them with the main house. An example would be a detached guest house or in-law suite on your property. Having Accessory Dwelling Units can provide you with the opportunity for more space, privacy, and convenience. 

  • Affordable housing options
  • Flexible living space for today’s busy families
  • Live in the home you already have rather than move to a new location
  • Increase your property value by adding an ADU

Is it Right for You?

Before you get started on making sure that this type of dwelling is right for your needs. Only build if there is a demand in the area and will be profitable enough. 

The Location

It is also extremely important to make sure that there are no city ordinances or restrictions on building a secondary dwelling unit. You need to check with your local planning department as well as the fire and police departments.

What are Your Options?

There are three types of accessory dwelling units: detached, semi-detached, or attached. A Detached Dwelling Unit is a separate structure from the main house. A Semi-Detached Dwelling Unit has a wall shared with another dwelling but it doesn’t extend all the way to ground level or roofline, leaving an open space between them. An Attached Dwelling unit shares at least one common wall and/or floor system with another dwelling unit or main house. The difference between these types is the degree of separation from your primary living space in the form of walls, floors, and ceilings.

  • Detached: You’re able to keep your privacy because it’s a completely separate structure from the main house. No one will be in your business if 

  you decide not to share. 

  • Semi-Detached: If you like experiencing new things every day, then this is 

  for you as there is no open space between structures and could change 

  depending on whether or not other tenants move out. 

  • Attached: There are always going to be people right next door so this 

  The option isn’t ideal if you don’t want any of your neighbors knowing what’s 

  up with you and vice versa.

What should I consider before buying or building an ADU?

Many things need to be considered and planned for when looking into purchasing a property with the plan of adding on as an accessory dwelling unit. The first thing to consider is whether or not the property you are looking at purchasing has enough space for an ADU. You will need to make sure that there is room on the property where you want your accessory dwelling unit added.

  • Your needs
  • Your budget
  • Your return on investment
  • Your city’s zoning rules
  • Your own time and energy restrictions

Who Are You Building it For?

If you are building an ADU, who will be using it? Are they going to take care of the maintenance on the property or is that your responsibility as well?  Are they going to be living in it full-time or only on the weekends? Are you planning on renting out your ADU and if so, what type of renter is looking for?

Having an ADU on your property has several advantages. Here are some of the most frequent uses for ADUs:

  • A mother-in-law flat
  • A guest house
  • An income property
  • A home office
  • A studio of an artist

Will Your Community Approve an ADU?

Before you start building anything make sure that there is no city code against having a detached unit on your property. Some areas have a limit on the number of units that can be added to a piece of property and you might not know if yours is one of them until it’s too late.

How much does it cost to build an ADU?

The average accessory dwelling unit costs $75,000 – $100,000. This figure will vary widely depending on the size of the home and what amenities and features you would like to add.

How Are You Going To Fund It?

It costs money to build an ADU, but there are many different ways that you can fund building one. Are you hoping to build it yourself or will you hire contractors? Are there grants available for ADU’s in your area? Are they tax deductible and if so, what percentage of the cost is refunded back to you by filing an itemized return?

What Are You Going to Use?

Building an ADU is easier with some tools than others. Are you planning on building it yourself or are you going to hire contractors? Are there certain types of permits that will need to be filed for your project and what’s the cost associated with them?

What Will Be Your Landlord Responsibilities?

Once you have a renter for your ADU, what do you need to take care of? Are they going to pay the utilities or will it be up to you and if so, how much is included in their rent payment? Are there any restrictions on smoking or pets and who pays for damage caused by them?

What Are You Going to Provide?

When you agree on a lease with your renter, what will they be getting in the unit and how is it going to compare with their expectations when they move in? Are there any appliances that are provided or do they have to bring them themselves? Are all repairs paid for by the tenant or are certain ones your responsibility? Are there any rules that they have to follow when it comes time to vacate the unit and will you provide a walk-through of how things should be left before leaving?

How Are You Going To Maintain It?

An ADU is an investment, but what does it take for upkeep on one in your area? Are there any types of inspections required before you can rent it out? What are the renter’s responsibilities when it comes to keeping up with maintenance and how much notice do they need for you to enter their unit?  Are all repairs your responsibility or are you splitting them with the renter? Are there any types of upgrades that need to be made every few years and who pays for those costs?

  • Follow the important steps for creating and maintaining a 

                         successful, legal ADU

  • Learn about how to navigate county requirements and regulations
  • Find out what renters need to keep their unit up with regular 


  • Get an idea of when you can expect upgrades on your property

Homeowners are opting to create accessory dwelling units, which can be a great way for them to increase the functionality of their property and boost its value when it comes time to sell.

Installing an ADU in your home can be a great investment, but it’s important to research the project and make sure permits were obtained before construction begins. 

Are You Planning an Accessory Dwelling Unit (ADU) But Don’t Know Who to Trust?

Get started on your dream ADU today! New Key Construction, based in Walnut Creek California, specializes in spectacular accessory dwelling units. Our passion is to be the home for talented craftsmen who deliver beautiful projects to clients throughout the Contra Costa County region! Need a solution for your in-laws, long-term guests, or a growing family? ADUs have become the go-to popular solution for families throughout Contra Costa County! An ADU is also known as an in-law house, backyard house, guest house, or casita; basically a small home that can be built on the same lot alongside another, larger single-family home.  Ready to get started? Check out our website, our portfolio and our reviews to learn more – or give us a call to start your project today.