Accessory Dwelling Unit (ADU) Ordinance

ADU web graphic

ACCESSORY DWELLING UNIT ORDINANCE ADOPTED MAY 31, 2022

Background

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 will go 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.

13839 - May 31, 2022 Accessory Dwelling Units v3

 

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.


What is an accessory dwelling unit?

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.

 

What zones permit ADUs?

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

 

What areas of the city permit ADUs?

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.

 

What type of dwellings can construct an ADU?

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.

 

How many ADUS can I build on my property?

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

 

Can I subdivide my ADU and put it on a separate lot?

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.

 

Do I need to live on the property?

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

 

Can I rent my ADU as a short-term vacation rental or long term rental?

Potentially. The City of Chattanooga has a short-term vacation rental boundary that allows certain properties to be eligible to apply for a permit to short-term rent (less than 30 days) a dwelling. The City Council passed a moratorium prohibiting any new permits for non-owner occupied short-term vacation rentals until Jan. 2023. 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.

 

What size ADU can I build?

The ADU cannot exceed 700 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.

 

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 of principal dwelling unit is 1-story: Shall be no more than 24’ when measured to the peak of the roof for all roof slopes. 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
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Detached ADU when height of principal dwelling unit is 1-story
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Attached ADU
 Click image to enlarge.

 

Will I need to replace parking if I convert my garage to an ADU?

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.

 

Can I use a “tiny home” as an 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 700 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.

 

I’m in a Historic District. Can I build an ADU?

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 https://chattanooga.gov/public-works/land-development-office/historic-planning-and-design-review.

 

Where can I find information about the cost of a building permit and other fees?

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

When do I pay my building permit fee?

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.

 

I received a notification to pay my building permit fee. How do I pay for it?

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

 

How do I pay for the building permit by cash or check as opposed to online methods?

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.

 

What are the rules regarding conversion of non-habitable (non-living) space such as a garage and storage area into an ADU?

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

 

How do I start the permit process?

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 & clarify requirements for your project. Contact 423-643-5800 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.

 

How long does it take to get my plans approved?

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.

 

How can I get an inspection?

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.

 

When will I get an 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.

 

Can I build a new house and an ADU at the same time?

Yes, separate permits are required for each unit.

 

Is an ADU required to have its own address?

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

 

What are the application requirements?

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


Contact

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

For more information related to the building code and construction process, contact the Development Review and Permitting Office at 423-643-5800 or email: ADUChattanooga@chattanooga.gov