Herriman City Zoning Code

The purpose of this chapter is to regulate the proper development and use of accessory dwelling units (ADUs) -including internal and detached types - within Herriman City. This chapter implements the City's Moderate Income Housing Plan, advances the goals of the General Plan, and ensures that ADUs are developed in a manner compatible with existing neighborhoods, protect public health and safety, and optimize land use.

The legislative intent of the City Council is based on the following findings:

1. Policy. Herriman City's General Plan and Utah Code § 10-9a-403 require strategies to promote moderate-income housing.
   
2. Community. Accessory dwelling units provide affordable housing options, support aging in place, and optimize land use without altering neighborhood character.
3. Regulatory. Industry best practices and policy guidance recommend streamlined permitting, owner occupancy, and design compatibility for ADUs.
4. Authority. This chapter is adopted pursuant to Utah Code Annotated § 10-9a-101 et seq., is consistent with Herriman City Code Title 10, and advances public health, safety, and welfare.

The following definitions apply to this chapter:

1. Accessory Dwelling Unit (ADU). A self-contained residential unit located on the same lot as a single-family dwelling, containing its own kitchen, bathroom, and sleeping facilities, and subordinate in size and use to the principal dwelling. ADUs are classified as either internal or detached, as defined below:
   
   1. Internal Accessory Dwelling Unit (IADU). An ADU that is contained entirely within, or attached to, the principal single-family dwelling, including units created within a basement, garage conversion, or addition to the principal structure.
      
   2. Detached Accessory Dwelling Unit (DADU). An ADU that is physically separated from the principal single-family dwelling and located on the same lot or parcel. This definition does not include ADUs that are internal or attached to the principal dwelling. (Cross reference HCC 10-3-5 "Accessory Building or Structure")
      
2. Owner Occupant. For purposes of this chapter, the property owner is defined as the titleholder of the lot or parcel, or an immediate family member such as a parent, child, spouse, sibling, or grandchild, who occupies either the principal dwelling or the ADU as a primary residence.
3. Short-Term Rental. A rental of a dwelling unit for a period of fewer than 30 consecutive days, as defined in HCC 10-3-6.

1. Internal ADUs. Internal ADUs shall be permitted in all zoning district that allow a single-family residential dwelling as a permitted or conditional use per HCC 10-16 Tables of Uses, subject to compliance with the regulations of this chapter. No minimum lot size is required for an internal ADU beyond what is required for the principal dwelling in the applicable zoning district.
   
2. Detached ADUs. Detached ADUs shall be permitted in all zoning districts that allow a single-family residential dwelling as a permitted or conditional use per HCC 10-16 Table of Uses, on lots or parcels with a minimum area of 10,000 square feet, subject to compliance with the regulations of this chapter.
   
3. One ADU Per Lot. Only one ADU - whether internal or detached - shall be permitted on any single lot or parcel. A property may not have both an internal ADU and a detached ADU simultaneously.
   
4. Subordinate Use. All ADUs are accessory uses and shall remain subordinate to the principal single-family dwelling in size and function. (Cross-reference: HCC 10-16 Tables of Uses; HCC 10-34 Accessory Buildings and Structures).
   

The following standards apply to both internal and detached ADUs unless otherwise specified in Sections 10-36-6 or 10-36-7.

1. Owner Occupancy.
   
   1. The property owner shall occupy either the principal dwelling or the ADU as a primary residence.
      
   2. The property owner shall submit a legal affidavit for recording with the Salt Lake County Recorder, certifying that the property is the owner's primary residence and that the owner lives on the property. A Notice of Owner Occupancy Requirement shall be recorded against the property title.
   3. Upon receipt of a complaint regarding compliance with the requirements of this section, the property owner shall provide evidence to the City in the form of a driver's license, voter registration, or tax documents that list the address of the subject property as the primary residence.
   4. Exceptions for owner occupancy may be granted for up to two (2) years for temporary military or religious service, provided an on-site property manager is provided during the period of absence.
2. Short-Term Rental Prohibited. ADUs shall not be used as short-term rentals as defined in HCC 10-3-6. Rental of fewer than 30 consecutive days are prohibited.
   
3. No Separate Sale. ADUs shall not be sold separately from the principal dwelling.
   
4. Business License. A business license shall be required if the ADU is rented for long-term occupancy. (Cross-reference: HCC 10-5-9 Permitted Uses; HCC 10-5-22 Zoning Compliance Review)
   
5. Utilities. ADUs shall connect to municipal water and sewer. Connections shall be made through the existing meters and service connections of the principal dwelling. Separate meters are optional and shall not require new road cuts or new lateral connections where existing connections are adequate.
6. Emergency Access. To ensure emergency access and delivery of public services to an ADU, the City shall;
   
   1. Assign and record a unique street address;
   2. Verify the street address is properly installed and plainly visible from one or more adjacent public or private rights-of-way;
   3. Require an improved pedestrian path from the adjacent public or private right-of-way to the ADU;
   4. If a fence encloses the property, ensure that pedestrian access from the adjacent public or private right-of-way is self-evident and unobstructed, except by a functional gate, and
   5. If deemed necessary by emergency personnel, require installation and maintenance of directional signage and appropriate illumination of the pedestrian path.
7. Impact Fees. Impact fees shall be assessed in accordance with the adopted City Fee Schedule. Staff shall develop and bring to the City Council recommendations for impact fees applicable to ADUs, including fees for police, fire and roads.
8. Compliance with Title 10. Unless otherwise specified within this chapter, all ADUs shall comply with all applicable provisions of Title 10, including Chapters 10-34 (Accessory Buildings and Structures) and 10-29 (Supplementary and Qualifying Regulations).

1. Location. Internal ADUs shall be located entirely within or attached to the principal single-family dwelling, including within a basement, attached garage conversion, or addition to the principal structure. Internal ADUs shall not be located in a detached accessory structure.
   
2. Maximum Floor Area. The maximum floor area of an internal ADU shall not exceed fifty percent (50%) of the gross floor area of the principal dwelling, or 1,000 square feet, whichever is less.
   
3. Entrance. Internal ADUs shall have a separate entrance from the principal dwelling, which may be located on the side or rear of the structure. A shared interior entrance between the principal dwelling and the internal ADU is permitted.
   
4. Design Standards. Any addition to the principal dwelling to accommodate an internal ADU shall be constructed of materials and colors that complement the principal dwelling and shall comply with the architectural standards in HCC 10-29-45 and HCC 10-34-4.
   
5. Parking. One (1) additional off-street parking space shall be provided for the internal ADU. Tandem parking is permitted. (Cross-reference: HCC 10-24 Off-Street Parking).
   
6. Height and Setbacks. Internal ADUs shall comply with the height and setback requirements applicable to the principal dwelling in the applicable zoning district, as no separate structure is created.

1. Maximum Floor Area. The maximum floor area of a detached ADU shall not exceed 1,000 square feet, excluding covered or enclosed square footage reserved for off-street parking. A detached ADU shall not be larger in floor area than the principal single-family dwelling on the same lot.
   
2. Height. Detached ADUs shall not exceed twenty-five (25) feet in height.
   
3. Setbacks.
   
   1. Rear yard: Ten (10) feet minimum.
   2. Side yard: Eight (8) feet minimum.
   3. Corner lots: Maintain a clear sight triangle per HCC 10-29-51.
   4. Detached ADUs shall not be located within a public utility easement or other recorded easement.
   5. Detached ADUs shall not be located in the front-yard of a lot or parcel.
4. Design Standards.
   
   1. Detached ADUs shall be constructed of materials and colors that complement the principal dwelling.
   2. Roof pitch shall be similar to that of the principal dwelling.
   3. Window placement adjacent to the adjoining properties may be permitted to provide light and air, but shall be designed to protect privacy in compliance with the following requirements:
      1. Window placement within the first floor of a detached ADU may be permitted upon compliance with applicable building codes.
      2. Window placement within the second floor, attic, or loft space of a detached ADU that has an exterior unobstructed view into an adjacent private residence or yard requires a minimum windowsill height of 6 feet, measured from the elevation of the corresponding floor plate.
   4. Development or architectural deviations: The Planning Commission may approve deviations from one or more of the developmental or architectural standards provided in this chapter based on a finding that the proposed development provides compensating design features that mitigate any reasonably anticipated detrimental effects, as per the approval standards in HCC 10-5-10(E). (Cross-reference: HCC 10-5-10(E) Approval Standards; HCC 10-29-45 Single-Family Attached or Detached Dwelling Standards; HCC 10-34-4 Architectural Standards).
5. Parking.
   1. Two (2) additional off-street parking spaces shall be provided for a detached ADU that is 650 square feet or larger.
   2. One (1) additional off-street parking shall be provided for a detached ADU that is smaller than 650 square feet.
   3. Tandem parking is permitted.
   4. When a detached garage is converted to a detached ADU, any parking spaces required for the principal dwelling that were located within the detached garage shall be replaced on-site. (Cross-reference: HCC 10-24 Off-Street Parking).

The following table summarizes the key dimensional standards for each ADU type for quick reference. In the event of a conflict between this table and the text of this chapter, the text shall control.

Existing accessory structures that do not meet current building or zoning standards for new detached ADUs may be converted only upon satisfaction of the following criteria:

1. Criteria for Approval.
   
   1. Lawful Establishment. The structure was legally built in accordance with prior codes or approved permits before the adoption of this chapter.
   2. Life-Safety Correction. All deficiencies necessary for safe habitation - including structural stability, egress, and fire safety - can be corrected without expanding the footprint or height beyond permitted limits.
   3. No increase in Nonconformity. Conversion does not worsen existing noncompliance with setbacks, lot coverage or height.
   4. Neighborhood Compatibility. The structure's location and design do not create unreasonable impacts on privacy, noise, or access.
   5. Utility Feasibility. Adequate water, sewer, and power connections can be provided without adverse impacts.
2. Criteria for Denial
   
   1. The structure cannot be brought into compliance with minimum life-safety standards without substantial expansion.
   2. Conversion would result in significant detrimental impacts, including but not limited to blacking emergency access or severe privacy intrusions.
   3. Utilities or infrastructure cannot be reasonably provided.
3. Special Exception. If compliance cannot be achieved without minor expansion or modification, the applicant may request a special exception from the Planning Commission, which may impose conditions to mitigate impacts.
   
4. Nonconforming Structures - Grandfathering. A pre-existing permitted building that exceeds the dimensional standards for an ADU under the nonconforming provisions of this chapter, provided that:
   
   1. The structure was lawfully established before the adoption of this chapter;
   2. The conversion does not increase the degree of nonconformity; and
   3. The converted ADU meets all parking, owner-occupancy, utility, and operational standards of this chapter. (Cross-reference: HCC 10-34 Accessory Buildings and Structures).

1. Pre-Application Meeting. Upon request, a property owner or authorized agent may schedule an optional pre-application meeting with the Planning Department to discuss the ADU permit process and applicable requirements.
   
2. Permitted Use. All ADUs shall be processed as a permitted use upon compliance with this chapter. No conditional use permit shall be required for an ADU located in a primarily residential zone.
   
3. Building Permit. A building permit shall be required for all ADUs. Proposed building plans shall comply with applicable building, fire, and health codes.
   
4. Streamlined New-Construction Permitting. An applicant may obtain a building permit for a single-family dwelling that included an ADU as part of the same application, subject to:
   
   1. Recording a Property Notice requiring owner occupancy with the Salt Lake County Recorder; and
   2. Business license registration for all operable ADUs that are rented for long-term occupancy.
5. Business License. A business license shall be required if the ADU is rented for long-term occupancy (Cross-reference: HCC 10-5-9 Permitted Uses; HCC 10-5-22 Zoning Compliance Review)
   

Under the direction of the Planning Director, city staff shall track and report to the City Council inquiries and applications from residents who:

1. Request an ADU on a lot smaller than 10,000 square feet; and
2. Request both an internal and a detached ADU on the same lot.

This data shall be used to inform future policy adjustments and amendments to this chapter as needed.

If any provision of this chapter is declared invalid by a court of competent jurisdiction, such invalidity shall not affect the remaining provisions, which shall continue in full force and effect.

This ordinance shall take effect upon publication as required by law.