The dimensional requirements for the single-family residential zones are stated in table 2A-2, located at the end of this section. Each of the following subsections describes in more detail the regulations for each of the dimensional requirements listed in the table. Provisional uses and uses allowed by special exception may have specific dimensional requirements not specified in table 2A-2, located at the end of this section. Approval criteria for these uses are addressed in chapter 4, article B of this title. Dimensional requirements may be waived or modified for developments approved through the planned development (see chapter 3, article A, "Planned Development Overlay Zone (OPD)", of this title) or through the historic preservation exception as outlined in section 14-2A-7, "Special Provisions", of this article.
A. Minimum Lot Requirements:
1. Purpose: The minimum lot area and width requirements are intended to ensure that a lot is of a size, width, and frontage that is appropriate for the uses permitted in the subject zone and will ensure, in most cases, that the other site development standards of this title can be met. The lot area per dwelling unit standards control the intensity of use on a lot to ensure consistency and compatibility of new dwellings with the surrounding development.
2. Standards: Generally, the minimum lot area and width standards for the various single-family residential zones and for specific residential uses are stated in table 2A-2, located at the end of this section.
3. Minimum Lot Sizes For Specific Land Uses:
a. Provisional uses and uses allowed by special exception may have specific lot size requirements not specified in table 2A-2, located at the end of this section. Approval criteria for these uses are addressed in chapter 4, article B, "Minor Modifications, Variances, Special Exceptions, And Provisional Uses", of this title.
b. If a minimum lot size is specified within a zone for a particular land use or dwelling type, whether permitted, provisional or a special exception, that use or dwelling type may not be established on a smaller lot, even if smaller lots are permitted in the subject base zone, except as permitted under chapter 4, article E, "Nonconforming Situations", of this title.
B. Minimum Setback Requirements For Principal Buildings:
1. Purpose: The minimum setback requirements are intended to:
a. Maintain light, air, separation for fire protection, and access for firefighting;
b. Provide opportunities for privacy between dwellings;
c. Reflect the general building scale and placement of structures in the city's neighborhoods;
d. Promote a reasonable physical relationship between buildings and between residences; and
e. Provide flexibility to site a building so that it is compatible with buildings in the vicinity.
2. General Setback Requirements: Generally, the minimum required setbacks for principal buildings in residential zones are stated in table 2A-2, located at the end of this section. The minimum setbacks for principal buildings create required setback areas within which principal buildings are not allowed, except for certain building features as specified in this subsection.
3. Specific Setback Requirements: The following provisions contain setback requirements that apply in specific situations:
a. Setbacks Along Arterial Streets:
(1) On lots platted after December 31, 1983, a minimum forty foot (40') front setback is required along any lot line that abuts an arterial street or future arterial street as shown on the Iowa City arterial street map, located in chapter 5, article C, "Access Management Standards", of this title.
(2) If a lot is located along an arterial street that is substandard with regard to the width of the public right of way as specified in title 15, "Land Subdivisions", of this code, then the minimum forty foot (40') front setback along said street is increased by the number of additional feet that will be required for future upgrade of said street to city standards. Lots platted prior to December 31, 1983, are exempt from this requirement. In addition, setback averaging may apply in certain circumstances. (See subsection B3e of this section.)
b. Lots With Multiple Frontages:
(1) On corner lots, no building, structure or planting, unless specifically exempted, may be located within the vision triangle, as set forth in chapter 5, article D, "Intersection Visibility Standards", of this title.
(2) If a lot fronting on two (2) or more streets is required to have a front setback, a minimum setback equal to the required front setback must be provided along all streets, and such setback will be considered a front setback for purposes of this title.
c. Lots With Multiple Buildings: The principal buildings on the lot must be separated by a horizontal distance of at least ten feet (10'). Proximity of building walls will be subject to all current building code fire protection requirements.
d. Overlay Zones And Special Districts: If specific setbacks have been established in a historic or conservation district, a planned development, or in the central planning district, those setbacks supersede the setback requirements of the base zone. For properties located in a historic or conservation district, refer to chapter 3, article B of this title and also the applicable setback provisions in the Iowa City historic preservation handbook. For a property located in a planned development overlay zone, refer to the approved planned development overlay plan for the subject property. For two-family uses, multi-family uses, group living uses, and institutional/civic uses located on property in the Central Planning District, refer to the applicable setback provisions in section 14-2B-6, "Multi-Family Site Development Standards", of this chapter.
e. Setback Averaging:
(1) Where at least fifty percent (50%) of the lots along a frontage have been developed and all of these developed lots are occupied by principal buildings that are located at least five feet (5') further from the street than the required front setback, the required front setback along the frontage is increased to the equivalent of the setback of the building closest to the street. However, this averaging provision does not apply to frontages that contain three (3) or fewer lots.
(2) Where at least fifty percent (50%) of the lots along a frontage are occupied by principal buildings that are located closer to the street than the required front setback, the front setback may be reduced to the average of the respective setbacks on the abutting lots. Only the setbacks on the lots that abut each side of the subject property along the same street may be used to calculate the average. Setbacks across the street or along a different street frontage may not be used. When one abutting lot is vacant or if the lot is a corner lot, then the average is based on the setback of the nonvacant lot and the required setback for the zone in which the lot is located. (See figure 2A.2 of this section.)
4. Building Features Permitted Within Required Setback Area: The following building features may extend into the required principal building setback area, subject to the conditions indicated and provided that location of such a feature does not violate the provisions of chapter 5, article D, "Intersection Visibility Standards", of this title. The setback regulations for detached accessory structures and structures not considered part of the principal building are addressed in chapter 4, article C, "Accessory Uses And Buildings", of this title.
a. Awnings, uncovered balconies, bay windows, belt courses, buttresses, canopies, chimneys, cornices, sills, and other similar features that extend beyond the wall of a principal building may project up to six feet (6') into the required front or rear setbacks. Except for balconies, bay windows, and chimneys, all such projecting building features may extend up to three feet (3') into the required side setback. Balconies and bay windows may not extend into the required side setback. Chimneys may extend up to two feet (2') into the required side setback. Projections from the principal building must in all cases be at least two feet (2') from any side lot line.
b. Enclosed porches, covered decks, and covered patios that are attached to the principal building must comply with the principal building setbacks of the base zone and may not extend into the required setback area. Unenclosed and screened-in porches (non- habitable space) may extend up to fifteen feet (15') into the rear setback, provided they are set back at least twenty feet (20') from the rear lot line. The standards for uncovered decks and patios are specified in chapter 4, article C, "Accessory Uses And Buildings", of this title. Enclosed porches, covered decks, and covered patios that are attached to an accessory building must comply with the standards for accessory buildings as specified in chapter 4, article C, "Accessory Uses And Buildings", of this title.
c. Fire escapes may extend into any setback, provided they do not extend more than three feet (3') into any side setback.
d. Stairways that function as the principal means of access to dwelling units located above the ground or first floor of a building may not extend into any required setback.
e. Stoops and wheelchair ramps that function as a means of access to the ground or first floor of a building may extend into the rear setback, up to eight feet (8') into the required front setback, and into the side setback, provided they are set back at least three feet (3') from any side lot line. In cases where, due to topography or other site characteristics, a wheelchair ramp cannot meet this standard, a minor modification may be requested according to the approval criteria and procedures for minor modifications contained in chapter 4, article B of this title.
5. Adjustments To Principal Building Setback Requirements:
a. A minor modification to reduce principal building setback requirements may be requested according to the approval criteria and procedures for minor modifications contained in chapter 4, article B of this title.
b. A special exception may be requested to reduce principal building setback requirements beyond what is allowed by minor modification. The Board of Adjustment may adjust setback requirements if the owner or lawful occupant of a property demonstrates that the general special exception approval criteria and the following specific approval criteria have been satisfied:
(1) The situation is peculiar to the property in question;
(2) There is practical difficulty in complying with the setback requirements;
(3) Granting the exception will not be contrary to the purpose of the setback regulations; and
(4) Any potential negative effects resulting from the setback exception are mitigated to the extent practical.
(5) The subject building will be located no closer than three feet (3') to a side or rear property line, unless the side or rear property line abuts a public right-of-way or permanent open space.
C. Building Bulk Standards:
1. Maximum Height:
a. Purpose: The height regulations are intended to promote a reasonable building scale and relationship between buildings; provide options for light, air, and privacy; and discourage buildings that visually dominate other buildings in the vicinity.
b. Standards: Generally, the maximum height standards for structures in single-family residential zones are stated in table 2A-2, located at the end of this section. Height standards for accessory buildings are addressed in chapter 4, article C, "Accessory Uses And Buildings", of this title.
c. Exemptions: If allowed in the subject zone, the following structures or parts thereof are exempt from the height limitations set forth in the zones indicated, provided an increase in height does not conflict with chapter 6, "Airport Zoning", of this title:
(1) Chimneys or flues.
(2) Spires on religious or other institutional buildings.
(3) Cupolas, domes, skylights and other similar roof protrusions not used for the purpose of obtaining habitable floor space.
(4) Farm structures, including barns, silos, storage bins and similar structures when accessory to an allowed agriculture use.
(5) Flagpoles that extend not more than ten feet (10') above the height limit or not more than five feet (5') above the highest point of the roof, whichever is less.
(6) Parapet or fire walls extending not more than three feet (3') above the limiting height of the building.
(7) Poles, towers and other structures accessory to a basic utility use, such as street lights and utility poles.
(8) If allowed in the subject zone, basic utilities and communication transmission facilities are exempt from the base zone height standards, but are subject to any limitations placed by the Board of Adjustment.
(9) Roof structures, including solar energy systems, elevator bulkheads, stairways, ventilating fans, cooling towers and similar necessary mechanical and electrical appurtenances required to operate and maintain the building.
(10) Television antennas and similar apparatus.
d. Adjustment Of Height Standards:
(1) The maximum height for a principal building may be increased; provided, that for each foot of height increase above the height standard, the front, side, and rear setbacks are each increased by an additional two feet (2'); and provided, that an increase in height does not conflict with the provisions of chapter 6, "Airport Zoning", of this title.
(2) A minor modification may also be requested to adjust the maximum height for a particular building or property according to the procedures and approval criteria for minor modifications contained in chapter 4, article B of this title.
2. Minimum Building Width:
a. Purpose: The minimum building width requirements promote a reasonable building scale and relationship between dwellings in a neighborhood.
b. Standards: The minimum building width requirements for principal structures in single-family residential zones are stated in table 2A-2, located at the end of this section. A principal building must be in compliance with the specified minimum building width for at least seventy five percent (75%) of the building's length. (See figure 2A.3 below.)
D. Maximum Lot Coverage Standards:
1. Total Building Coverage:
a. Purpose: The total building coverage standard helps to define the character of single-family residential zones by limiting the land area that can be covered by buildings. These standards work in conjunction with the minimum lot requirements and building bulk standards to determine how built up a neighborhood appears.
b. Standards: The total building coverage standards for the various single-family residential zones are stated in table 2A-2, located at the end of this section. The maximum building coverage standard establishes the percentage of the total area of a lot that can be covered by buildings. The total building area of all buildings on the property, including both principal and accessory buildings, is used to calculate the building coverage.
2. Front Setback Coverage:
a. Purpose: The front setback coverage standard ensures that a certain portion of the front setback area remains free of impervious surface, which helps to maintain a consistent and pleasant environment along neighborhood streets. These standards increase public safety by preventing excessive front yard paving and vehicular storage that may obscure the principal dwelling and the main entrance from view of the street. In addition, this standard helps to prevent neighborhood streets that are dominated by front yard pavement, particularly along frontages with narrow residential lots.
b. Standard: The maximum front setback coverage standard for the single-family residential zones is stated in table 2A-2, located at the end of this section. The table lists the maximum percentage of the required front setback that may be covered by impervious surface, including driveways, walkways, patios, decks, and other paved areas. Front setback coverage may not exceed the percentage indicated in said table 2A-2.
c. Exception: A special exception may be requested to increase the allowed front setback coverage. The Board of Adjustment may adjust the front setback coverage standard if the owner or lawful occupant of a property demonstrates that the general special exception approval criteria set forth in chapter 4, article B of this title, and the following specific approval criteria have been satisfied:
(1) The lot is of an irregular shape or contains severe topography, such that there is practical difficulty meeting the front setback coverage standard.
(2) The applicant has demonstrated that every effort has been made to design buildings, paved areas, and vehicular use areas to meet the front setback coverage standard. Such efforts include reducing the width of driveways, reducing paved areas and size of garages and providing alternative means of vehicular access to the property. If vehicular access to an alley or private rear lane is available, the front setback coverage standard may not be increased.
(3) Granting the exception will not be contrary to the purpose of the front setback coverage regulations.
(4) Any potential negative effects resulting from the exception are mitigated to the extent practical.
E. Minimum Open Space Requirements:
1. Purpose: The minimum open space requirements are intended to ensure a minimum amount of private, usable open space is provided to support the health, well-being and enjoyment of the residents of the dwelling. The intent of the open space is to support passive recreation, leisure activities, informal gathering, and opportunities for interaction with nature.
2. Minimum Requirements:
a. On lots that contain multi-family uses or group living uses, usable open space shall be provided on each lot at a ratio of ten (10) square feet per bedroom, but not less than four hundred (400) square feet, located in one or more clearly defined, compact areas, with each area not less than two hundred twenty five (225) square feet with no dimension less than fifteen feet (15'). On lots that contain multi-family uses in the RS-12 zone, a minimum of one hundred fifty (150) square feet of usable open space per unit shall be provided, located in the rear yard with no dimension less than ten feet (10').
b. On lots that contain detached single family uses, a minimum of five hundred (500) square feet of usable open space shall be provided, located in the rear yard with no dimension less than twenty feet (20').
c. On lots that contain attached single family uses, a minimum of one hundred fifty (150) square feet of usable open space shall be provided, located in the rear yard with no dimension less than ten feet (10').
d. On lots that contain two family uses, a minimum of three hundred (300) square feet of usable open space per dwelling unit shall be provided, located in one or more clearly defined, compact areas, with each area not less than three hundred (300) square feet with no dimension less than twelve feet (12').
3. Standards:
a. For multi-family uses and group living uses, open space shall meet the standards as set forth in subsections 14-2G-7E1 through E7 of this chapter, except that multi-family uses in the RS-12 zone shall comply with the standards below.
b. For single family uses, two family uses, and multi-family uses in RS-12 zones, open space shall be located behind the principal dwelling in an area visible and easily accessible from the principal dwelling and shall consist of open planted green space, which may include trees, planters, gardens, and other amenities that support passive recreation or leisure activities. Paved areas shall not be counted toward usable open space. For attached single family uses, rooftop or upper floor open air terraces or rear yard-facing porches, including screened-in porches (non-habitable space only) may count toward the open space requirement.
4. Minor Modification: A minor modification may be requested according to the provisions and approval criteria of section 14-4B-1, "Minor Modifications", of this title, to reduce the required open space for single family and two family uses in the following circumstances, provided the additional approval criteria stated in subsection E4e of this section, are satisfied. Note that reducing the open space may reduce the allowed occupancy of a rental property (see title 17, chapter 5, "Housing Code", of this Code):
a. In order to establish up to two (2) off-street parking spaces (surface parking or in a garage) on a lot that currently has fewer than two (2) off-street parking spaces; or
b. If the lot is a corner lot, is irregular in shape, substandard in size, or contains severe topography, or other unique circumstance, such that there is practical difficulty meeting the standard; or
c. The lot contains a manufactured home, where due to the shape/dimensions of the home there is practical difficulty meeting the standard; or
d. The lot contains a detached zero lot line dwelling, where the side yard is designed to serve as usable open space for the dwelling;
e. Approval criteria:
(1) The applicant has demonstrated that every effort has been made to design buildings, paved areas, and vehicular use areas to meet the open space requirement. Such efforts may include but are not limited to reducing the width of driveways, reducing paved areas and size of new buildings or additions, and providing alternative means of vehicular access to the property; and
(2) The open space requirement will be satisfied to the extent possible in another location on the lot, such as a side yard; and
(3) Any potential negative effects resulting from the exception are mitigated to the extent possible.
Zone/Use | Minimum Lot Requirements | Minimum Setbacks | Building Bulk | Maximum Lot Coverage | Maximum Number Of Bedrooms Per Unit | Minimum Open Space (Sq. Ft.)10 | ||||||||
Lot Size (Sq. Ft.) | Area/Unit (Sq. Ft.) | Lot Width (Ft.) | Frontage (Ft.) | Front (Ft.) | Side (Ft.) | Rear (Ft.) | Maximum Height (Ft.) | Minimum Building Width (Ft.) | Total Building Coverage | Front Setback Coverage | ||||
Zone/Use | Minimum Lot Requirements | Minimum Setbacks | Building Bulk | Maximum Lot Coverage | Maximum Number Of Bedrooms Per Unit | Minimum Open Space (Sq. Ft.)10 | ||||||||
Lot Size (Sq. Ft.) | Area/Unit (Sq. Ft.) | Lot Width (Ft.) | Frontage (Ft.) | Front (Ft.) | Side (Ft.) | Rear (Ft.) | Maximum Height (Ft.) | Minimum Building Width (Ft.) | Total Building Coverage | Front Setback Coverage | ||||
RR-1 | Detached single- family, including zero lot line | 40,000 | 40,000 | 80 | 50 | 156 | 5+22 | 20 | 35 | 203 | 40% | 50% | n/a | 500 |
Other uses1 | 40,000 | n/a | 80 | 50 | 20 | 5+22 | 20 | 35 | 203 | 40% | 50% | n/a | n/a | |
RS-5 | Detached single- family, including zero lot line | 6,0008 | 6,0008 | 508 | 408 | 156 | 5+22 | 20 | 35 | 203 | 45% | 50% | n/a | 500 |
Duplexes | 10,000 | 5,000 | 70 | 70 | 156 | 5+22 | 20 | 35 | 203 | 45% | 50% | 411 | 300/unit | |
Attached single- family | 5,000 | 5,000 | 35 | 35 | 156 | 0 or 105 | 20 | 35 | 203 | 45% | 50% | 411 | 150 | |
Other uses1 | 6,000 | n/a | 50 | 40 | 20 | 5+22 | 20 | 35 | 203 | 45% | 50% | n/a | n/a | |
RS-8 | Detached single- family, including zero lot line | 5,0008 | 5,000 | 458 | 408 | 156 | 5+22 | See note 9 | 35 | 203 | 45% | 50% | n/a | 500 |
Duplex | 8,000 | 4,000 | 60 | 60 | 156 | 5+22 | See note 9 | 35 | 203 | 45% | 50% | 411 | 300/unit | |
Attached single- family | 4,000 | 4,000 | 30 | 30 | 156 | 0 or 105 | 20 | 35 | 203 | 45% | 50% | 411 | 150 | |
Other uses1 | 5,000 | n/a | 45 | 40 | 20 | 5+22 | 20 | 35 | 203 | 45% | 50% | n/a | n/a | |
RS-12 | Detached single- family, including zero lot line | 5,0008 | 5,0008 | 458 | 408 | 156 | 5+22 | See note 9 | 35 | 203 | 50% | 50% | n/a | 500 |
Duplex | 6,000 | 3,000 | 55 | 40 | 156 | 5+22 | See note 9 | 35 | 203 | 50% | 50% | 411 | 300/unit | |
Attached single- family | 3,000 | 3,000 | 20/287 | 20 | 156 | 0 or 105 | 20 | 35 | 183 | 50% | 50% | 411 | 150 | |
Multi-family uses | 9,000 | 3,000 | 76 | 60 | 156 | 10 | 20 | 35 | 543 | 50% | 50% | 411 | 150/unit | |
Other uses1 | 5,000 | n/a | 45 | 40 | 20 | 5+22 | 20 | 35 | 203 | 50% | 50% | n/a | n/a | |
RNS-12 | Detached single- family | 5,0008 | 5,0008 | 458 | 258 | 156 | 5+22 | See note 9 | 27 | 203 | 40% | 50% | n/a | 500 |
Duplex | 6,000 | 3,000 | 45 | 25 | 156 | 5+22 | See note 9 | 27 | 203 | 40% | 50% | 411 | 300/unit | |
Multi- family uses | 5,000 | Existing 4 | 45 | 25 | 156 | 5+22 | 20 | 35 | 203 | 40% | 50% | 311 | 10/bedroom, but no less than 400 | |
Other uses1 | 5,000 | n/a | 45 | 25 | 20 | 5+22 | 20 | 35 | 203 | 40% | 50% | n/a | n/a | |
n/a = not applicable
Notes:
1. Other uses must comply with the standards listed in this table unless specified otherwise in chapter 4, article B of this title.
2. Minimum side setback is 5 feet for the first 2 stories plus 2 feet for each additional story. Detached zero lot line dwellings must comply with the applicable side setback standards in chapter 4, article B of this title.
3. A building must be in compliance with the specified minimum building width for at least 75 percent of the building's length.
4. See the special provisions of this article regarding multi-family uses.
5. See applicable side setbacks for attached single-family as provided in chapter 4, article B, "Minor Modifications, Variances, Special Exceptions, And Provisional Uses", of this title.
6. The principal dwelling must be set back at least 15 feet, except on lots located around the bulb of a cul-de-sac; on such lots the principal dwelling must be set back at least 25 feet. On all lots, garages, both attached and detached, must be set back as specified in chapter 4, article C, "Accessory Uses And Buildings", of this title.
7. Minimum lot width is 20 feet for attached units on interior lots and 28 feet for end lots in a row of attached units. When only 2 units are attached, lots must be 28 feet wide.
8. If the single family density bonus options have been applied, the minimum lot area, lot area per unit, lot width and lot frontage requirements may be reduced accordingly. (See section 14-2A-7 of this article.)
9. The principal building rear setback is 20 feet, except in the Central Planning District and Downtown Planning District, where the rear setback is dependent on the depth of the lot. For lots equal to or less than 100 feet in depth: minimum rear setback = 20 feet. For lots greater than 100 feet in depth: minimum rear setback = lot depth less 80 feet. For purposes of this provision, garages located in the rear yard and attached to the principal dwelling with a (non-habitable) breezeway (8 feet or narrower in width) will be considered detached accessory buildings and, therefore, are subject to the setback requirements for detached accessory buildings, rather than principal building setback requirements. Similarly, subject breezeways shall be treated as detached accessory structures/buildings.
10. Open space must meet standards set forth in subsection 14-2A-4E of this section.
11. Outside of the University Impact Area (see map 2B.1 in Section 14-2B-6), the maximum number of bedrooms may be increased by one (1). Any bedroom within a multi-family, attached single family or duplex that exceeds 225 square feet in size or has any horizontal dimension greater than 16 feet shall count as 2 or more bedrooms, as determined by the City. The maximum number of bedrooms may be further constrained by the provisions of title 17, chapter 5, "Housing Code", of this Code.
(Ord. 05-4186, 12-15-2005; amd. Ord. 09-4365, 12-1-2009; Ord. 12-4488, 8-21-2012; Ord. 18-4744, 4-2-2018; Ord. 23-4893, 1-24-2023; Ord. 23-4914, 11-6-2023; Ord. 24-4919, 1-16-2024)