Accessory Dwelling Unit (ADU) Ordinance

ADU web graphic



As part of its efforts to support a range of housing options, the City Council adopted an ordinance that permits accessory dwelling units (ADUs) to be built within the City of Chattanooga. The ordinance went into effect June 14, 2022.

Historically, ADUs have been built throughout the city dating back to the early 1900’s. When the zoning ordinance was adopted in 1961, it prohibited ADUs. ADUs were first permitted in the downtown

Form Based Code area that was adopted by City Council in 2016, and the new ordinance extends ADUs city-wide.

The ADU Ordinance required a one-year review after the June 14, 2022 adoption.  Staff conducted the review in 2023.  The report and ordinance is below.

Accessory Dwelling Unit (ADU) Ordinance 1-Year Review

13839 - May 31, 2022 Accessory Dwelling Units v3

2024 Accessory Dwelling Unit Ordinance Amendments


What is an Accessory Dwelling Unit?

An accessory dwelling unit (ADU) is a secondary residential unit built on the same lot as an existing single-family home. ADUs are also referred to as a granny flat, carriage house or in-law suite.

ADUs can be created in a variety of ways, including conversion of a portion of an existing house such as a basement or attic, addition to an existing house, conversion of an existing garage or the construction of an entirely new, detached building. They also can be used in many ways, including rental units, home offices, studios, guest houses, and housing for multi-generation households, offering flexibility to households living in single-family neighborhoods.

Benefits of ADUs include efficient use of existing developed land and public infrastructure, creation of affordable housing opportunities, increased income opportunity for home owners, and the opportunity to care for an elderly or disabled family member in an independent living arrangement.

  • Click here for an informational video from Asheville, NC that describes the different types and uses of ADUs.

  • Click here for an informational video from the RPA about ADUs and how to begin the construction process.


Frequently Asked Questions

Below is a list of frequently asked questions related to ADU zoning and building construction. Click here for a copy of a handout with more information.

There are two types of ADUs: attached and detached.

An attached ADU is an additional or subordinate dwelling unit located on the same lot as the principal dwelling unit which is joined to another dwelling at one or more sides by a wall and contained entirely within the footprint of the principal dwelling unit. Examples include converted living spaces, attached garages, basements, attics, or building additions.

A detached ADU is an additional subordinate dwelling unit located on the same lot as the principal dwelling unit and is a stand-alone separate structure. This can include an existing garage that has been converted or a new unit added on a second story or other accessory structures detached from the principal dwelling unit.

ADUs are permitted in any zone that allows single-family detached dwellings.

ADUs are permitted in all areas of the city, outside the Form Based Code, for any property that has a single-family detached dwelling. For property that is located inside the Form Based Code, refer to Sec. 38-738.6.C- Use Categories, for different ADU standards.

ADUs are only permitted in conjunction with single-family detached dwellings. Townhouses, apartments, condominiums, duplexes or any other multi-family housing is not permitted to construct an ADU.

Each property that has a single-family detached dwelling can construct one ADU.

No, the ADU shall be owned by the same property owner(s) as the principal dwelling unit and cannot be subdivided or separated in ownership. Under no circumstances can the ADU be converted to a horizontal property regime or a fee simple condo.

No, the ADU can be rented unless there are restricted convents or other private Homeowner Association documents that prohibit renting your property.

Potentially. The City Council updated the short-term vacation rental regulations on May 16, 2023.  A permit from the Land Development Office is required.  The property may need to be rezoned to a commercial zone that allows hotels if the rental is going to be non-owner occupied (absentee). You can find out more information on short-term vacation rentals by visiting this website.

ADUs can be rented for long term rentals (more than 30 days) without applying for a permit unless the property has a homeowner association that restricts rentals. This is true for short-term vacation rentals also.

The ADU cannot exceed 800 square feet. This is measured by the exterior dimensions of the building. Sleeping lofts and interior stairwells that are conditioned are also added into this square footage.

Any ADU that is 701-800 square feet in size, then a second means of egress (two exit doors) is required by City code and garage doors do not count.

Yes. Although there is no minimum parking requirement for an ADU, existing parking for the principal dwelling unit must be maintained or replaced if on-site parking is lost due to the creation of the ADU.

Tiny houses on wheels are not permitted to be used as an ADU. The ADU must be a minimum of 200 square feet and a maximum of 800 square feet in size and must be constructed on a permanent foundation either through digging and pouring a footer or being attached to an existing permanent structure.

The ADU must be constructed on a permanent foundation either through digging and pouring a footer or being attached to an existing permanent structure. The building permit process will require the plans to have complete engineering and/or the materials must have a State seal of inspection at the factory. Manufactured homes must be installed by licensed installers and must have an installation decal applied after completion of the set-up.  Click here for more information on the State of TN building code requirements.

Yes, ADUs are permitted in local historic districts such as St Elmo, Ferger Place, Battery Place or Fort Wood. In addition to any other necessary permits, ADUs in historic districts require approval from the Chattanooga Historic Zoning Commission (CHCZ) including a Certificate of Appropriateness. The design is reviewed based on the guidelines set forth by the district, which may be more restrictive than the underlying zoning. Get to know your local historic district guidelines before developing ADU plans. Learn more or contact CHZC staff by phone at 423-643-5834or online at

The fee will be due after the permit application is reviewed by a staff member. You will get a notice via email once your application is approved.

You have the option of paying online with a credit card or in person. Paying online will save you a trip back to our office but you will be assessed an additional processing fee.

Service Fees

Returned Check Fee:  $30

Credit Card Fees: 2.99% of total transaction amount + $0.99 per transaction

Once you’re notified that payment is due, you can come to the Land Development Office and pay with a check. We no longer accept Cash. We would prefer it if you pay online since it is easy and automatic. In addition, all of your information is secure.

The conversion must meet all ADU ordinance requirements and current building and fire codes.

You can schedule a pre-submittal meeting with the Land Development Office staff to discuss the building permit process and all applicable codes and fees.  These are held on Tuesday & Thursday mornings.  Staff from several departments will be present to offer guidance and clarify requirements for your project. Contact 423-643-5894 to schedule a meeting.

All applications are available 24/7 through an online permitting portal. Applicants who wish to apply in-person at the Development Resource Center (DRC) will be assisted by Land Development Office staff in submitting their applications through ViewPoint at the front Kiosk. Paper application forms are no longer accepted. Applicants are notified via email when the permit application has been received and is being processed for review.

Typically 5-10 business days but this can vary depending on the number of permits submitted. Applicants are notified via email when their plans have been approved.

After a permit is obtained, login to the portal at least 24 hours in advance of when you want to request an inspection.

Busy times it may take up to 48 hours to get an inspection. Remember to have all of the required documents and information for your inspection.

Usually, an inspection can be scheduled for the next day after your request for an inspection has been received (weekends and holidays excluded). At busy times, it may take up two or more days to receive an inspection from the date of your request.

Inspection hours are Monday through Friday (excluding Holidays), 7:30 a.m. to 4:00 p.m. The inspectors are in the office from 7:30 to 8:00 a.m. and from 3:30 to 4:00 p.m. to answer calls. The rest of the day is spent out in the field performing inspections.

Yes, separate permits are required for each unit.

Yes, contact Hamilton County Geographic Information Systems Department at (423) 209-7760 or  for more information on obtaining an address.  Click here to review the Hamilton County Regional Addressing Policy.

Visit this link for a list of all fees.  Below is a graphic with a scale of fees for building permits

Scale of fees for building permits

You will need to submit the following information.  You can use this checklist as a guide to assist with the application requirements.


  • Floor plan

Floor plan

  • Site plan

Site plan

What is the maximum building height for an ADU?

Detached ADU when height of
principal dwelling unit is more
than 1-story:
24’ or 2 stories
maximum as defined by the
building code.
Detached ADU when height
principal dwelling unit is
Shall be no more than 24’
when measured to the peak of the
roof for all roof slopes. The height
of a detached ADU is measured
using the zoning definition, not the
building code. The inspector will
measure the height from the street

Attached ADU: Cannot exceed the
maximum height of the zone district
and cannot exceed the height of the
principal dwelling unit.
Detached ADU when height of principal dwelling unit is more than 1-story
Click image to enlarge.
Detached ADU when height of principal dwelling unit is 1-story
Click image to enlarge.
Attached ADU
 Click image to enlarge.



For more information related to the ADU zoning ordinance standards, contact the Regional Planning Agency at 423-643-5902 or email:

For more information related to the building code and construction process, contact the Development Review and Permitting Office at 423-643-5891 or email: