5 Simple Steps to Building an ADU

Building an ADU, or an accessory dwelling unit, has garnered a reputation for being more cost-effective and easier to build than renovations such as additions.

These small housing wonders gained popularity throughout California and are steadily taking root elsewhere as populations continue to grow and homeowners seek creative ways to make ends meet.

What to Know Before Building an ADU

Building an ADU is far from a simple task because of the complex laws that surround them; there’s no standardized requirements, or financing for ADUs.

These room additions offer many benefits, but it’s essential that you follow a plan in order to build a successful accessory dwelling unit.

Before you build your own, make sure to consider these steps to help simplify the process.

1. Secure Your Budget and Financing

Budget is the biggest obstacle faced by homeowners trying to expand or alter their existing space.

While the overall cost of building an ADU is less than building a large residence, it’s still a considerable amount for most homeowners and there are many factors to take into account.

When devising a budget make sure to include the cost of everything from labor and materials, to county and state fees, and even furnishings. It’s also a good idea to increase the budget 10 to 15 percent to account for unexpected occurrences faced once the project starts.

Financing Different Types of ADU’s

The most expensive ADU to build is the detached kind that sits away from the primary residence. Building these is essentially the same as building a small house; you have to figure in the fixed costs excavation and pouring a concrete foundation plus installing new utilities. These typically range from $112,000 to $285,000 to build.

Financing construction of a detached ADU can be tricky because many banks don’t offer traditional construction loans for this purpose. Other financing options exist including personal loans, equity lines of credit, and peer-to-peer lending sites.

Of course, building a detached standalone unit is only one option.

Another is to convert an attached garage into an apartment or studio. In this case your overall building cost would be less because the major infrastructure already exists. Converting a two-car garage into an ADU typically ranges from $20,000 to $60,000, depending on the features that you include.

Planning Your Accessory Dwelling Unit | Skyline Construction and Remodeling

2. Comply With Zoning Requirements

Ultimately, zoning requirements, rather than strictly budget, often dictate the attributes of building an ADU. You can’t build whatever size and shape ADU you want, where ever you want.

Your location will have its own restrictions regarding size, location, and permitting.

Recognize that regulations will differ across state lines, and even between different cities of the same state.

Regulations governing ADUs will stipulate such things as:

  • — How many of them you can have on your premises
  • — Their size compared to the primary residence
  • — Allocation of parking and storage space
  • — How the new residence will be addressed for mail
  • — Whether there is a shared or separate entrance

Some cities require specific permitting for ADUs in addition to the standard building permits.

You may be required to disclose how the new premises will be used- whether it will be used as a rental property or just additional space. Depending on how you expect to use the property, you might need to attend a public hearing and give your neighbors written notice of your intention to build.

3. Consult With a Contractor

Regulations surrounding zoning and permitting of ADUs is constantly changing; and navigating them is a daunting tedious process when you’re unfamiliar with their practical details.

Additionally, these regulations directly affect how the space will be used and configured. Those obstacles create the perfect opportunity to hire a contractor or architect for your project.

Both those professionals are intimately knowledgeable about the legal constraints that accompany an ADU, and they are familiar with how the codes affect each other and the final design of the space.

They’ll be able to optimize the square footage to give you the most usable space allowable without sacrificing safety and legality.

Hiring a contractor has other benefits as well. They’ll manage the permitting and inspection process, schedule skilled labor, and hire subcontractors.

Using a contractor saves homeowners valuable time, and prevents a lot of the stress than will accompany a remodel. When building an ADU with Skyline Construction and Remodeling, we handle all aspects of zoning and gathering of permits.

4. Design Your Space

The most fun part of building an ADU is actually designing it; putting in features and details that you want and creating a comfortable space to call your own.

Look for inspiration online, in magazines, or from television. Keep a notebook of ideas handy that you can give to your architect or contractor. Keep in mind that your space should be stylish, but also highly functional.

A multitude of floor plans are available that are structured towards accommodating small living spaces. You can borrow ideas from so-called “tiny homes,” RVs, and boats where space-saving storage techniques have been successfully used for years.

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5. Enter the Permitting Process and Begin Construction

Once you’ve nailed down the details, collected your ideas, and finalized your budget it’s time to start construction. It pays to be detail-oriented throughout this part of the process because you’ll be dealing with lots of variables.

Keep a calendar of important dates like inspections, prospective completion, and deliveries. This way you’ll have the timeline easily accessible to make unexpected changes.

If you’ve hired a contractor then you likely won’t have to do much once construction has started. By this time you’ll have finalized the layout and design of the space, chosen a color scheme, and have an idea how the space will look when finished.

The contractor will manage the labor and materials, and contend with local building officials.


Adding an accessory dwelling unit, or ADU, to your single-family home is a great way to increase your living space, or increase your income.

Despite their steady growth in popularity there’s still a lot of ambiguity surrounding how to build them.

Following the guidelines described above when building an ADU will streamline the experience so that you can start using your new space as soon as possible.

Still have questions? Contact us today to speak directly to our construction team and learn how Skyline Construction and Remodeling can help with your ADU or garage conversion.