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Boulder City Zoning Code

SUPPLEMENTARY REGULATIONS

§ 153.43 PURPOSE.

   The purpose of this chapter is to set forth standards for property development, maintenance, and use that may, and usually do, apply to several zoning districts. Standards for parking, landscaping, measurement of setbacks and height, and property maintenance not only will apply to every district established by these regulations, but they will contribute substantially to the preservation and enhancement of the city’s special character and qualities.
(Ord. 2025-03, passed 9-15-2025)

§ 153.44 HOME OCCUPATIONS.

   (A)   Requirements for permitted home occupations in the Residential R-1 District and Mixed-Use MU District. A home occupation may be conducted as a secondary use in a dwelling, provided that:
      (1)   The use of the dwelling for the home occupation clearly must be incidental and subordinate to its use for residential purposes, and not more than 33 percent of the floor area of the dwelling may be used in the conduct of the home occupation.
      (2)   There may be no change in the outside appearance of the building or premises, or other visible evidence of the conduct of the home occupation other than one sign, not exceeding six (6)square feet in area, nonilluminated and mounted flat against the wall of the principal structure.
      (3)   No traffic may be generated by a home occupation in greater volumes than would normally be expected in a residential neighborhood, and any need for parking generated by the conduct of the home occupation shall be met off the street. No home occupation, or any required parking for the home occupation, shall use the parking space required for the residence.
      (4)   No vehicles, except those normally used as passenger vehicles, will be used for the home occupation unless stored or parked elsewhere.
      (5)   No equipment or process shall be used in a home occupation which creates noise, vibration, glare, fumes, odors or electrical interference detectable by normal senses off the lot.
      (6)   Any equipment or materials used in connection with a home occupation shall be stored within the principal residential structure or accessory building or in an enclosed space outside of the principal structure or accessory building.
   (B)   Home occupations allowed as conditional uses. Where a proposed home occupation would not conform to any one of the conditions specified in division (A) above, the home occupation must be reviewed as a conditional use under the procedures of Section 153.36.
(Ord. 2025-03, passed 9-15-2025)

§ 153.45 FLOODPLAIN REGULATIONS.

   All development in the Special Flood Hazard Area (formerly known as the FEMA 100-year floodplain), according to current FEMA Flood Insurance Rate Maps (FIRM) (https://msc.fema.gov/portal/search#searchresultsanchor), shall comply with the Floodplain and Floodway Management standards set forth in Title 15, Chapter 152 of the City of Boulder Municipal Code.
(Ord. 2025-03, passed 9-15-2025)

§ 153.46 STRUCTURAL HEIGHT MEASUREMENT.

   The “height of a structure” is defined as the mean linear distance from the ground level on finished grade at the midpoint and immediately adjacent to each of the walls of a structure to the highest point of the structure, not including antennas, chimneys, steeples, or roof-top mechanical devices. Structural height is further determined as follows.
   (A)   Highest point of a structure. The highest point of a structure is the top of the highest roof pitch for a hip or gabled roof, or top of parapet for a flat roof not including any mechanical structures. Steeples, chimneys, antennas, receiving dishes, and the like, are not subject to limitations of structural height, except cell towers which are limited to 35 feet in height in the MU and CB Districts and 70 feet in the GC.
   (B)   Finished grade. Finished grade shall be construed as the grade at the base or foundation of a structure necessary to achieve positive drainage away from the structure only. Soil, fill, or other material may not be bermed against a structure to circumvent height limits.
   (C)   Natural grade. Natural grade shall be construed as meaning that the natural slope and topography of the land need little or no modification to site the structure. Where the nearest two points to natural grade are at different grades (such as, a house that takes up grade through the structure), the heights measured may be averaged.
(Ord. 2025-03, passed 9-15-2025)

§ 153.47 SETBACK MEASUREMENTS AND ALLOWABLE ENCROACHMENTS.

   (A)   Front setbacks.
      (1)   A required front setback is measured at a right angle (90 degrees) from the front property line to the nearest of the following two points on the structure:
         (a)   The foundation wall of the principal structure; or
         (b)   The facing edge of a porch or deck over 16 square feet in area extending from the front of the principal structure.
      (2)   The following encroachments into the front setback are allowed:
         (a)   Steps are allowed to encroach into the required front setback up to eight feet;
         (b)   Ramps to provide accessibility to disabled persons may encroach up to 100%, but may not encroach onto the public right-of- way without special authorization from the owner of said right-of-way;
         (c)   Eaves may encroach up to two feet; and
         (d)   Porches and decks not exceeding 16 square feet in total area may encroach up to four feet.
   (B)   Side setbacks. A required side setback is measured at a right angle (90 degrees) from the side lot line to the nearest point of the foundation wall. Chimneys, eaves, bay windows no more than eight feet in total length, and garden windows may encroach no more than two feet into the required side setback.
   (C)   Rear setback. A required rear setback is measured at a right angle from the rear setback line to the nearest point on the foundation wall. Eaves may encroach no more than two feet, a deck or porch of no more than 16 square feet, and total area may encroach no more than four feet.
(Ord. 2025-03, passed 9-15-2025)

§ 153.48 OUTDOOR LIGHTING STANDARDS.

   All outdoor lighting shall be downcast and shielded. No light trespass shall be allowed, and no glare (direct sightline to an unshielded light source) shall be visible from off-site. This includes all light sources such as freestanding luminaires, building mounted lighting, and canopy lighting.
(Ord. 2025-03, passed 9-15-2025)

§ 153.49 OFF-STREET PARKING STANDARDS.

   (A)   Purpose: The purpose of the off-street parking requirements is to provide the following:
      (1)   Convenient and safe access to property;
      (2)   Alleviate hazards associated with access to traffic generating commercial and industrial uses;
      (3)   Provide adequate and safe parking areas for residents and business customers;
      (4)   Protect residential uses from the undesirable effects of abutting traffic generating uses and parking areas; and
      (5)   Maintain the traffic carrying capacity of the street system serving Boulder.
   (B)   Definition: For the purpose of this title, an “off-street parking space” consists of a space adequate for parking an automobile with room for opening doors on both sides, together with properly related access to a public street or alley and maneuvering room.
   (C)   When Required:
      (1)   No building or structure may be erected, substantially altered, or its use changed unless permanently maintained off-street parking and loading spaces have been provided in accordance with the provisions of this title.
      (2)   The provisions of this section, except where there is a change of use, do not apply to any existing building or structure. Where a change of use involves no additions or enlargements, there shall be provided as many of such spaces as required by this title.
      (3)   Whenever a building or structure constructed after the effective date of this title is changed or enlarged in floor area, number of employees, number of housing units, seating capacity, or otherwise to create a need for an increase in the number of existing parking spaces, additional parking spaces must be provided on the basis of the enlargement or change; provided, whenever a building or structure existing prior to the effective date of this title is enlarged to the extent of fifty percent (50%) or more in floor area, number of employees, number of housing units, seating capacity or otherwise, said building or structure will then and thereafter comply with the full parking requirements set forth herein.
   (D)   Location and Design.
      (1)   Off-street parking as required by this chapter shall be located and designed as follows:
         (a)   Single-family dwellings: On the same lot with the dwelling they are required to serve.
         (b)   Multifamily dwellings: On the same lot with the dwelling they are required to serve.
         (c)   Hospitals, sanitariums, apartments, rooming and boarding houses, fraternity and sorority houses: Within 100 feet of the use they are required to serve.
         (d)   Commercial and industrial zones: Within 300 feet of the use they are required to serve.
         (e)   All off-site parking areas must be accessible by a public street or alley.
         (f)   All off-street parking spaces for residential units and commercial and institutional uses shall be at least eight (8) feet wide and 20 feet long, exclusive of access driveways, yards or ramps. Such spaces shall have a vertical clearance of at least seven feet.
         (g)   A plan of the proposed off-street parking facility shall be submitted along with the application for a zoning permit for the building the off-street parking is required to serve. Said plan shall clearly indicate construction details, fencing and other features which may be required by the zoning administrator.
         (h)   Off-street parking areas serving multi-family residential developments of more than ten (10) units, commercial, industrial or institutional uses must comply with the following provisions:
            1.   Grading and drainage. Parking areas shall be graded and drainage facilities installed to remove or retain surface run-off in a manner that does not adversely affect adjacent properties, public streets or surface waters.
            2.   Surfacing. Parking areas shall be surfaced with gravel or equivalent material (three-quarter inch-1½ inches). Parking areas containing 20 or more spaces shall be surfaced with asphalt, concrete or other hard surface.
            3.   Striping. Stalls in paved parking areas shall be marked with painted lines not less than four inches wide.
   (E)   Calculation of Off-Street Parking:
      (1)   Off-Street Parking in the R- Residential and MU Mixed Use District: One off-street parking space is required for each residential unit containing less than ten (10) units. For example, each single-family residential unit must have one (1) off-street parking space. A duplex must have two (2) off-street parking spaces, a tri-plex must have three (3) off street parking spaces and so on for the various types of residential developments and number of residential units.
   The number of off-street parking spaces required by land use is outlined below in Table 1:
Table 1 Parking Requirements
Table 1 Parking Requirements
Residential Uses
Single family-Condominiums-Townhomes
1.0 spaces per dwelling unit
Multifamily up to nine (9) residential units
1.0 spaces per dwelling unit
Apartments (10) residential units or more
1.0 spaces per dwelling unit
Bed and Breakfast Inns
1.0 space per guest room
Short Term Rental (AirBnB-VRBO)
1.0 space per dwelling unit
Single-family residential unit less than 1,200 square feet in size.
0.5 space per dwelling unit
Commercial and Institutional Uses
Automobile and machinery sales and service
1.0 space per 1,000 sq. ft. of floor area
Open sales area, trailer sales and rental
1.0 space per 1,500 sq. ft. of floor area
Business and professional offices, banks
1.0 space per 300 sq. ft. of floor area
Bowling alley
5.0 spaces per alley
Churches and other places of worship
1.0 space per four seats
Community or recreation center
1.0 space per 200 sq. ft. of floor area
Convenience stores/gas station combination
4.0 spaces minimum
Dancehall, skating rinks, court clubs
1.0 space per 200 sq. ft. of floor area
Furniture, appliance, household and equipment sales
3.0 spaces per 1,000 sq. ft. of floor area
Hospitals
1.0 space per bed
1.0 space per doctor
0.5 space per employee
Libraries and museums
1.0 space per 1,000 sq. ft. of floor area
Manufacturing and industrial uses
1.0 space per 1,000 sq. ft.
or 0.75 space per employee
Medical and dental offices
1.0 space per 250 sq. ft., or
1.0 spaces per doctor or dentist
1.0 space per employee
Motels and hotels
1.0 space per each guest room,
1.0 space per employee on maximum shift
Mortuaries and funeral homes
1.0 space per four seats
Nursing, convalescent and rest homes
1.0 space per three beds
1.0 space per employee on maximum shift
Restaurants and bars
1.0 space per 100 sq. ft.
Restaurants: fast-food
1.0 space per 100 sq. ft.
1.0 space per employee on maximum shift
Retail stores
1.0 space per 300 sq. ft.
Schools: Elementary, Middle
1.0 space per employee
1.0 space per two classrooms
Schools: High School
1.0 space per employee
1.0 space per five students
Service stations, automobile repair and services
1.0 space per 600 sq. ft.
Theatres, auditoriums, assembly halls with fixed seats
1.0 space per four seats
Warehousing or storage buildings, freight terminals
1.0 space per 300 ft. of office floor area
 
   (F)   Handicap Accessible Parking Specific Standards.
      (1)   Accessible (handicapped) parking spaces, eight (8) feet wide and 20 feet long shall be provided according to the Figure 1 and Table 2. Handicapped parking spaces shall be clearly identified with a sign bearing the international handicapped accessible symbol and marked “Reserved for Handicapped.”
      (2)   Van accessible spaces. One out of each eight accessible spaces provided, but at least one space in each parking facility, shall be van accessible.
      (3)   Location. Accessible parking spaces shall be located so as to provide the shortest accessible route to a primary building entrance.
      (4)   Curb ramps and accessible routes. Curb ramps and accessible routes shall be provided which allow unobstructed travel from an accessible parking space to an accessible entrance. Parked vehicle overhangs shall not reduce the clear width of an accessible route. Parking spaces and access aisles shall not exceed 2% grade in all directions.
 
Table 2
Total spaces in lot
Minimum number of ADA accessible spaces, with one van accessible
4-25
1
26-50
2
51-75
3
76-100
4
>100
2 percent of total
 
   Figure 1 Layout of Standard and Van Accessible Parking Spaces
 
   (G)    Maintenance of Multi-Family, Commercial and Institutional Parking Lots: The owner of property used for parking must maintain such area in good condition without potholes, accumulation of snow and remain free of trash and other debris.
(Ord. 2025-03, passed 9-15-2025)

§ 153.50 FENCING STANDARDS.

   Fences and retaining walls are allowed as accessory structures in all zoning districts, subject to zoning permits. The following standards must be met:
   (A)   Fencing - Retaining Wall.
      (1)   Height; materials. In the R Residential District, no fence, hedge, or freestanding wall (not part of a building) located within or bounding all of the required lot setbacks, may exceed 72 inches (6-feet) in height. This maximum fence height includes the height of a privacy screening fence located on top of a deck. Allowable fencing materials and designs include:
         (a)   Wood or vinyl (including PVC) picket or rail fencing;
         (b)   Metal fencing;
         (c)   Concrete block or wood timber retaining walls and
         (d)   Other similar materials and designs as approved by the Zoning Administrator.
      (2)   Institutional security fencing. Open security fencing up to eight (8) feet in height may be allowed by the Zoning Administrator for schools, correctional facilities, and other public and quasi-public institutions when necessary for the safety or restraint of the occupants thereof, without regard to the setbacks specified in division (A)(1) above.
      (3)   Obstruction at intersection. No portion of any fence shall pose a visual obstruction at any street intersection. (See 153.51 of this chapter for standards.)
      (4)   Ornamental pedestrian entries. Ornamental pedestrian entries, such as arches or arbors, shall not exceed ten feet in height.
      (5)   Wire products. In the R Residential District and MU District, barbed wire, razor wire, concertina wire, and similar wire products are not allowable fencing materials.
      (6)   Open security fencing. In the CB and GC Districts, for commercial storage areas located inside or rear yards, open security fencing may be constructed up to eight feet in height and may be topped with barbed wire. The barbed wire etc. course is calculated as part of the allowable fence height.
      (7)   Wildlife fences in excess of six feet. Any fence, or any portion of a fence, used for keeping wildlife off of a property that is over 72 inches in height (6-feet) must be made of a transparent material such as traditional plastic mesh deer fence.
      (8)   Maintenance. A zoning permit is not required for the repair and maintenance of existing fencing where the repair and maintenance does not change the height or footprint/location of the fence.
(Ord. 2025-03, passed 9-15-2025)

§ 153.51 CORNER VISIBILITY.

   (A)   Corner visibility triangle. Every street intersection shall have associated with it a corner visibility triangle. This area shall be created by extending the property lines based upon survey pins to an imaginary point in the street where the lines intersect. From that point, 30 feet is measured back along each line, then a line across both ends is drawn to close the triangle. In most cases, this triangular area will include both public right-of-way and private property adjacent to the right-of-way.
 
   (B)   Visibility standards. Within the corner visibility triangle, there shall be no continuous obstructions between the heights of 30 inches and ten feet, as measured from the adjacent road surface. This includes landscaping, fencing, and structures of all kinds.
   (C)   Applicability. This standard applies to streets of all functional classifications but does not apply to intersections of a street and an alley.
(Ord. 2025-03, passed 9-15-2025)

§ 153.52 MAJOR RECREATIONAL EQUIPMENT.

   (A)   Parking and storage. Major recreational equipment shall not be parked or stored on any City street right-of-way within the R-Residential or MU-Mixed Use District for longer than a 14-day period (consecutive days). However, major recreational equipment may be parked anywhere on a property except within the front yard setback. A conditional use permit must be obtained in order to park on any City street right-of-way within the R-Residential or MU-Mixed Use District for a period longer than 14 days.
   (B)   Use as living or sleeping quarters. A zoning permit must be obtained in order to use a major recreational equipment for sleeping, living, housekeeping, or any commercial purpose (including home-based business) and the equipment must be parked or stored on private property and must not be located within the front yard of a property. No major recreation equipment may be hooked up directly to City water or sewer services. Use of major recreational equipment as an accessory residential unit (ARU), or as guest quarters requires review and approval under the process for conditional uses found in Section 153.36.
(Ord. 2025-03, passed 9-15-2025)

§ 153.53 SIGNAGE.

   The intent of this subchapter is to coordinate the physical dimensions of signs to different land uses in the City’s zoning jurisdiction; to recognize commercial communication requirements of all sectors of the business community; to encourage the innovative use of design; to promote both renovation and proper maintenance; to mitigate the impacts of commercial signs on the city’s surrounding natural scenic beauty; to allow for special circumstances; to ensure that signs are constructed and installed properly; and to protect the public’s health, safety and general welfare.
   (A)   Hazardous Signs and Sign Maintenance.
      (1)   No sign permitted by this subchapter shall, due to its location, lighting, size, intensity, or color create a hazard to the safe, efficient movement of vehicular or pedestrian traffic.
      (2)   A sign as permitted by this subsection shall be maintained by the owner and kept in good condition.
      (3)   In addition, all parts and supports shall be routinely painted and repaired when in an unsafe, deteriorated or rotted condition.
      (4)   The surface of the ground under and about any freestanding sign shall be kept free of weeds, rubbish, or flammable waste material.
      (5)   Any sign determined to be hazardous by the Zoning Administrator shall be removed by the owner of the sign or be repaired or modified so that the hazardous conditions no longer exists within 30 days of written notification of the hazard unless otherwise specified.
   (B)   Signs Permitted in All Districts. The following signs shall be permitted in all zoning districts and shall not require a zoning permit:
      (1)   Signs advertising the sale, lease or rental of the premises upon which the sign is located;
      (2)   Legal notices, identification, information or directional signs erected or required by government bodies;
      (3)   Integral decorative or architectural features of buildings, except lettering, trademarks, moving parts or moving lights;
      (4)   Signs directing and guiding traffic and parking;
      (5)   Bulletin boards for churches, schools or other public, religious or educational institutions;
      (6)   Signs advertising yard sales; and
      (7)   Political advertising signs.
   (C)   Signs Permitted in all Mixed Use and Commercial Districts. Signage is permitted without a zoning permit if the following standards are met.
      (1)   No freestanding sign shall be set nearer to the lot line adjacent to a street than the required minimum setback for the principal uses permitted in the zoning district.
      (2)   No sign that overhangs the public right-of-way shall be closer than two and one-half feet from the curb or curb line.
      (3)   No sign that overhangs the public right-of-way shall be less than eight (8) feet from the surface of the right-of-way to the bottom of the sign.
      (4)   No on-site sign in the Central Business District shall exceed 30 feet in height as measured from either the grade at the sign or at the nearest roadway, whichever is greater.
      (5)   No on-site sign in the General Commercial shall exceed 40 feet in height as measured from either the grade at the sign or at the nearest roadway, whichever is greater.
      (6)   No on-site sign in the Mixed-Use District shall exceed 10 feet in height as measured from either the grade at the sign or the nearest roadway, whichever is greater.
      (7)   Signs for home occupation must meet the standards in Section 153.44.
      (8)   All signs located within the right of way managed by the Montana Department of Transportation (MDT) shall obtain the applicable permit from MDT.
      (9)   Any signage that does not meet these standards requires review under the process for a conditional use prior to installation as identified in Section 153.36.
(Ord. 2025-03, passed 9-15-2025)

§ 153.54 PLANNED UNIT DEVELOPMENT (PUD).

   (A)   Planned Unit Developments (PUD).
      (1)   Purpose. The purpose of this section is to allow, with adequate review, flexibility in the design of developments that do at least three (3) of the following:
         (a)   Encourage development with mixed uses, particularly a variety of housing types and densities;
         (b)   Create or preserve usable open space and recreation areas;
         (c)   Preserve the natural characteristics of the land including topography, native vegetation and scenic views;
         (d)   Avoid construction in unsuitable areas;
         (e)   Encourage creativity in design, including flexibility in residential siting to achieve energy conservation;
         (f)   Allow efficient provision of streets, utilities and other services; and
         (g)   Provide lower-cost housing affordable by low- and moderate-income families within the community.
      (2)   Definition. A Planned Unit Development (PUD) is a land development project designed and planned as a single entity under a plan that offers a variety of land uses, housing types and densities, and design features in addition to those allowed by right or condition in the zoning district.
      (3)   Application and review.
         (a)   Any person requesting approval of a planned unit development shall submit an application for conditional use under the provisions of 153.36. The application shall be accompanied by the required review fees and a PUD plan, described below.
         (b)   The PUD plan shall provide the following:
            1.   A vicinity map showing the location of the site in relationship to surrounding areas and showing the existing land uses and zoning of the site and surrounding properties;
            2.   A map drawn to approximate scale showing: Location, types and heights of existing and proposed buildings and other structures, including density and number of dwelling units or other uses of each structure;
            3.   Existing and proposed streets, alleys, bikeways, pedestrian walkways and vehicle circulation patterns, off-street parking areas;
            4.   Locations, dimensions and sizes of common and open space areas and those that will be left in a natural state; and
            5.   Physical features such as streams, ponds, canals, rights-of-way, utilities.
         (c)   A written statement describing:
            1.   A schedule for installing improvements, developing lots and constructing structures;
            2.   Proposed types of ownership of dwelling units and other uses, and restrictive covenants, if any; and
            3.   Means of providing maintenance of common facilities and open space areas;
            4.   A PUD will be reviewed and approved under the procedures for conditional uses pursuant to Section 153.36. Where the proposed PUD is subject to review as a subdivision under the State Subdivision and Platting Act, the Zoning Commission and Planning Board shall hold joint and concurrent review, including a joint public hearing(s). Notice of each hearing shall be given in the manner prescribed by this chapter and the municipality’s subdivision regulations.
            5.   A PUD must conform to the conditions prescribed by the Zoning Commission pursuant to Section 153.36 Conditional Uses.
(Ord. 2025-03, passed 9-15-2025)