ADU Knowledge
January 21, 2024

How Much are Permits for ADU - A Guide for Homeowners

Argi Avetisyan
Argi Avetisyan
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How Much are Permits for ADU - A Guide for Homeowners
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The concept of Accessory Dwelling Units (ADUs) has been a hot topic in the housing market, acting as a potential solution to the ongoing housing crisis. For many homeowners, the idea of building an ADU not only serves as an additional income stream but also offers the possibility of keeping loved ones close without sacrificing independence. However, amidst the numerous benefits, one pivotal aspect often overlooked is the cost of obtaining the necessary permits.

In this extensive guide, we will delve deep into the world of ADU permits, shedding light on their significance, the potential financial impact they may have on your project, and how to navigate them effectively. Whether you're contemplating constructing an ADU for rental income or to accommodate family members, understanding ADU permitting is crucial for a successful and compliant build.

Understanding ADU Permits

Before diving into costs and regulatory fees, it's essential to grasp the purpose of ADU permits and their relation to construction legality. ADU permits are official approval granted by a local government that allows you to build, expand, or renovate an ADU on your property. These permits ensure that your project complies with building codes, zoning laws, safety regulations, and governmental guidelines.

The permitting process for ADUs varies from state to state, and in many cases, even city to city. Typically, it involves submitting detailed plans of your proposed ADU and receiving approval from various local committees or departments, such as planning, zoning, building, and health. The process can be complex, involving multiple stages of review, inspection, and compliance checks.

Factors Affecting Permit Costs

The cost of obtaining ADU permits can fluctuate widely, influenced by several crucial factors:

1. Location-specific Regulations and Fees

Local governments impose different regulations and fees for ADU construction. Some areas might have streamlined their permitting processes to encourage ADU development, offering economic incentives for homeowners, while others may have strict guidelines, high fees, or even a waiting period.

Case Study: San Francisco

In San Francisco, a homeowner faced significant ADU permit costs due to stringent local regulations. The city required additional geotechnical reports and seismic upgrades for hillside ADU construction, significantly driving up the final permit bill.

2. Size and Complexity of the ADU Project

Larger or more complex ADUs, such as those that require significant structural modifications, electrical or plumbing overhauls, may incur more robust permit costs. These projects often demand more detailed plans and inspections, which translate to higher fees.

3. Additional Requirements and Inspections

Certain features or additions, like parking spaces, emergency exits, water and sewage hookups, and energy efficiency standards, might result in additional requirements and, consequently, higher permit costs.

Typical Cost Ranges for ADU Permits

To provide actionable insights, let's consider some examples of permit costs in different cities or regions across the United States.

1. San Francisco, California

In San Francisco, where construction and land costs are already high, ADU permits can start from $10,000 and quickly escalate depending on the project's complexity and location-specific requirements.

2. Portland, Oregon

The average permit cost for a simple ADU project in Portland, Oregon, falls in the range of $3,000 to $5,000. This estimate includes local fees, system development charges, and the building permit.

Case Study: Portland

A homeowner in Portland was able to reduce their permit costs by working with a contractor who had strong relationships with the local permitting office. This partnership expedited the process and ensured compliance while keeping the expenses at a minimum.

3. Los Angeles, California

LA's ADU permit costs can vary widely, starting at approximately $2,500 for pre-approved designs and reaching upwards of $20,000 for custom ADUs that require more extensive reviews and additional upgrades.

While these numbers provide a general idea, they are by no means a one-size-fits-all for every ADU project. Furthermore, keep in mind that permit costs are just one piece of the financial puzzle. You should also consider application fees, professional design drawings, development impact fees, and other related expenses.

Tips for Reducing Permit Expenses

Despite potentially high costs, there are ways to navigate the permit process more cost-effectively:

Research Local Regulations and Requirements

Begin your ADU journey by thoroughly researching your local zoning ordinances, building codes, and ADU policy frameworks. Understanding the rules upfront can save you from expensive surprises during the planning or construction phase.

Work with Knowledgeable Professionals

Hiring an architect or contractor with ADU experience can be invaluable. These professionals can design your ADU to meet current building standards, which is likely to reduce the need for plan revisions and re-submissions, ultimately saving you time and money.

Consider Permit Expediting Services

Professional permit expediters can navigate the complicated permit process on your behalf. While these services come at an additional cost, they can streamline the review and approval process, ensuring your permits are obtained faster.

Importance of Proper Permitting

Proper permitting is crucial for several reasons:

  • Legal and Safety Compliance: Building without permits can lead to fines, and more importantly, it often means your ADU does not meet essential safety and construction standards.
  • Property Value: Unpermitted structures can cause issues when selling your property, potentially leading to a decrease in value or even impeding the sale altogether.
  • Insurance: Home insurance policies may not cover damages or liability claims for unpermitted structures, putting you at significant financial risk.


Obtaining ADU permits is a critical step in the construction process that should not be taken lightly. It's an investment in the safety of the inhabitants, the legal protection of your property, and ensuring a streamlined path when deciding to sell or refinance.

As a homeowner, you have the responsibility to be well-informed about the potential costs and procedures associated with ADU permitting. By understanding the factors that influence permit costs, researching local regulations, and enlisting the help of experienced professionals, you can minimize expenses and ensure a compliant and safe ADU build.

Remember, this guide is only a starting point. Each ADU project is unique, and professional guidance tailored to your specific circumstances is always recommended. Dive into your local regulations, seek the counsel of experts, and embark on your ADU journey with confidence.

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Not sure where to start with your ADU project?


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