Constructing an ADU

NOTE: Total construction time averages 3 - 9 months with 3 - 6 months being ideal.

Steps in the Process

1. Secure Permit-Ready Plans
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The first step to building your Accessory Dwelling Unit (ADU) is creating building plans. You can hire an architect to create these or browse the City's digital ADU Permit-Ready Plan Library. Permit-ready plans include ADU floor plan designs and 80% building plans. This can save you time and money. View the ADU Permit-Ready Plan Library.

2. Secure Financing
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To build an ADU, you may need a loan to help pay for ADU construction. It is important to find a loan that fits your budget. The City provides information on different banks' ADU financing tools. For these resources, see Financing an ADU.

3. Hire a Contractor
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During the same time that you find a loan, you can also look for a contractor. Hiring a contractor is crucial to building an ADU. A contractor will ensure your ADU is built safely and correctly. They can also act as your project manager. They can make sure you have the right permits and construction is on-schedule. For guidance on choosing a contractor, plus a list of registered contractors, see Finding an ADU Contractor.

4. Get a Permit
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Once you have ADU plans, you will need to apply for a residential building permit with the City's Development Services Department (DSD).

You may also need other permits for things like electrical, mechanical, or plumbing. For more information, visit the DSD website or call 210-207-1111.

5. Construction Project Management
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Construction project management involves supervising and directing a project's stages. Managing ADU construction is time-consuming, so many people hire a project manager. A project manager might be a contractor or another professional. For more information on hiring a City-recommended contractor, see our ADU Contractor List.

Property & Zoning Requirements

ADUs are allowed in most residential zoning districts. Zoning is the legal use of land, and a zoning district says how a property can be used. For example, a property zoned for "single-family residential use" can have one house and one ADU.

  • Permitted Zoning Districts: R-1, R-2, R-3, R-4, R-5, R-6, RM-4, RM-5, RM-6, and in multi-family (MF) districts with fewer than five units.
  • In zoning districts that allow ADUs, only one ADU is permitted to be built on the property. Additionally, the property owner must live on-site in the main house or in the ADU. If the property owner does not live in the main house or in the ADU, the property must be rezoned to allow more than one main house.
  • To learn more about property zoning, contact DSD or check their OneStop map.
  • For tips on construction and hiring a contractor, see Finding a Contractor.

Frequently Asked Questions

Will my Homeowner's Association (HOA) allow me to build an ADU?
While the City will issue permits for ADUs that meet eligibility criteria, we strongly recommend checking to see if you have HOA regulations or deed restrictions that prohibit them.
Can I build an ADU if I live in a historic district?
ADUs are possible in historic districts. The permitting process is the same, but you will need a Certificate of Appropriateness (COA) before receiving a permit. See ADUs in Historic Districts for more information.
Do I need an architect to build an ADU?
No. In San Antonio, construction plans for ADUs do not require an architect to prepare.
Do I need an engineer?
Yes. The foundation construction plans are required to be approved and certified by an engineer.
Does my ADU need separate utilities from my main house?
Homeowners can choose whether the ADU is connected to the utilities of the main house or has separate utility connections.
Will my ADU have a separate address from my main house?

If the ADU will share a meter with the main house, you will not need a new address for the ADU. Instead, the ADU address will fall under the main house address.

If you want your ADU to have a separate meter, you will need an address to set up new utility connections. To submit a request for an address, you can complete a Request of Address Assignment/Verification (PDF) form online.

You can also complete this form in person with DSD:

Cliff Morton Development and Business Services Center (One Stop)
1901 S. Alamo St.
San Antonio, TX 78204
Directions

Information about visiting our office.

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