Form, Dimensional, and Site Design Standards

Purpose. This chapter sets the form, dimensional, and site design standards for development in every zoning district. The standards calibrate the size, placement, and configuration of buildings; the relationship between buildings and the public realm; and the site elements (entrance, parking, transparency, articulation) that determine how a building meets its surroundings. The standards implement the form-factor, prioritized-circulation-mode, activity-character, and geolocating-principle anchors stated in each district's intent statement at Section 11-2-2.

Applicability. This chapter applies to every development that establishes a new building, expands an existing building, or alters the exterior of a building in a manner subject to the standards in this chapter. The chapter does not apply to interior remodeling that does not alter the building exterior or change the use.

Hierarchy. Where a standard in this chapter is calibrated per district, the calibrated value in the applicable district controls. Where a standard in this chapter is uniform across the City, the citywide value controls. Where the A-grid and B-grid layer modifies a calibrated standard along a particular frontage, the modification under Section 11-4-11 controls for that frontage.

Two types of standards. This chapter carries two types of standards.

Coverage. Every district carries dimensional standards under Section 11-4-4. Districts whose intent prioritizes pedestrian or bicycle circulation, or where the historic and existing development pattern reads as a pedestrian-oriented public realm, additionally carry form standards under Sections 11-4-5 through 11-4-10; the form-standard sections identify which districts carry which standards.

Conflict. Where a dimensional standard and a form standard would produce different results for the same building, the form standard controls, because the form standard is the more specific and intent-aligned instrument. The dimensional standards continue to apply to elements the form standard does not address.

Measurement. Heights, setbacks, lot coverage, lot area, and the other dimensional and form measurements in this chapter are measured as Section 11-1-13 specifies.

Construction requirements for moved structures. Structures constructed off-site and moved to a permanent location may be used at the permanent location if the structure and its foundation comply with the building code provisions applicable at the time the structure is moved onto the site. For manufactured and factory-built housing, the structure must have been constructed in compliance with the applicable federal manufactured-housing standards at the time of its production and must be placed on a permanent foundation. This subsection implements the protections of 76-25-303(1)(a) for manufactured and factory-built housing.

Townhouses. Townhouses are a permitted residential building type in the districts identified in the Chapter 2 use tables, subject to the supplemental use standard at Section 11-2-9. The supplemental use standard carries the form, lot-configuration, and party-wall standards that the retired R-U district used to carry; this chapter's setback, lot-coverage, and height standards apply to townhouses in the district where they are built, modified by the townhouse supplemental standard where the supplemental standard speaks.

Vertical exceptions to height limits. The height limitations of any district do not apply to spires, belfries, cupolas, chimneys, water tanks, elevator housings, solar energy systems, streetlights, utility poles, and similar non-occupied vertical elements that do not add habitable building floor area.

Lot adjustments. A lot that existed at the effective date of this UDO and does not conform to the dimensional standards of the district in which it is located may be developed under those standards as if it conformed, provided no further reduction in the nonconformity is created. Lots may be redesigned or aggregated to reduce nonconformities without a variance. Lots created after the effective date of this UDO must conform to the dimensional standards of the district in which they are located.

Standards. Every lot must meet the general dimensional standards for the zoning district in which the lot is located. The standards are

Calibration. The per-district values for each standard are stated inline in this section, calibrated by district family and intensity. The values for districts that translate from a current district are ported from the current Title 11 Chapter 4 Table 2; the values for net-new districts (RMX-5, CMX-2, CMX-3, CMX-4, IMX-1) are stated as TBD until the office sets them.

Multi-frontage lots. A lot with more than one front lot line provides a front-lot-line setback for each front lot line. The remaining lot lines are side lot lines and no rear-lot-line setback is required. The remaining side lot lines must meet the minimum side-lot-line setback for the district.

Secondary-access setback. A lot line that abuts a public right-of-way that provides only a secondary means of access to property and is not intended for general travel may carry a reduced setback of five feet, in lieu of the otherwise-applicable side or rear setback.

Garage setback. The vehicular entrance of a garage must be set back at least twenty feet, measured in a straight line from the vehicular entrance to the lot line abutting the public right-of-way the garage's driveway approach uses.

Sight distance triangle. The sight distance triangle as required in Title 7, Chapter 3 of the City Code must be observed for corner lots regardless of the minimum setbacks otherwise applicable.

Standards. Where this section applies to a district, every site must meet the site standards calibrated for the district. The standards are

Calibration. The per-district values are stated inline in this section. Form standards apply only to districts whose intent statement at Section 11-2-2 prioritizes pedestrian or bicycle circulation or where the district's existing form pattern carries the site form the standards address.

Coverage of the site standard. Where a district carries a lot-coverage-minimum standard under subsection A(3), the standard applies in addition to the lot-coverage-maximum standard under Section 11-4-4(A)(2). The lot-coverage-minimum is the form-standard discipline that prevents excessive surface parking, large yards, or other low-coverage configurations from undermining a district's intended pedestrian-oriented form; the lot-coverage-maximum is the dimensional-standard floor that prevents over-building. The two standards together state the band within which the building's footprint must sit.

Standards. Where this section applies to a district, every building must meet the building-placement standards calibrated for the district. The standards are

Calibration. The per-district values are stated inline in this section.

Building-placement standards apply only to the ground floor story. The standards do not apply to upper stories or to interior remodeling.

A-frontage and B-frontage designation.

Corner lots and multiple-frontage lots. On a corner lot or a lot with multiple street frontages, building placement must conform to the A-frontage and B-frontage standards for each frontage as designated under subsection D; a corner-lot orientation adjustment is not available, and the building meets both frontages' standards by design. Where the building cannot meet both frontages' standards simultaneously, the proposed development requires a variance under Section 11-4-13.

Standards. Where this section applies to a district, every building must meet the height-and-massing standards calibrated for the district. The standards are

Calibration. The per-district values are stated inline in this section.

The wall-segment articulation requirement in subsection A(4) is satisfied by an offset, projection, or recess of a depth specified in the calibration values, by a change in material or fenestration pattern sufficient to read as an articulation, or by a vertical articulation element that breaks the wall segment into shorter visual components.

Building height is measured from the ground floor story at grade.

Standards. Where this section applies to a district, every building must meet the transparency standards calibrated for the district. The standards are

Calibration. The per-district values are stated inline in this section.

Transparency is measured as the percentage of the relevant facade area between the ground floor story (or upper-story floor) and the underside of the ceiling (or roof) that consists of transparent glazing, including window openings, doorway openings with glazed doors, and similar transparent elements. Spandrel glass, mirrored glass, and other non-transparent treatments do not count toward the transparency minimum.

Standards. Where this section applies to a district, every building must meet the pedestrian-access standards calibrated for the district. The standards are

Calibration. The per-district values are stated inline in this section.

The pedestrian-access standards apply to ground floor entrances; upper-story entrances are not subject to these standards.

Standards. Where this section applies to a district, every site must meet the parking-placement standards calibrated for the district. The standard is

Calibration. The per-district values are stated inline in this section.

The parking-placement standard governs where parking is placed on the lot. Parking-quantity standards — the number of spaces required or permitted — are a separate operational rule that the office's parking standards address; this section does not state those standards.

The parking-placement standard, like the building-placement and transparency standards, supports the prioritized circulation mode each district's intent statement identifies. In districts whose intent prioritizes pedestrian circulation, parking placement to the rear or side preserves the pedestrian frontage; in districts whose intent prioritizes vehicle or freight circulation, this standard is calibrated less restrictively or does not apply.

Grid layer. The A-grid and B-grid layer of the Official Zoning Map, established under Section 11-1-8(B), modifies the form standards in Sections 11-4-5 through 11-4-10 along the frontages it identifies. Every street is on either the A-grid or the B-grid; the grid designation determines which of the two calibrated values applies to each form standard along the frontage.

Criteria for A-grid membership. A street is on the A-grid if it carries one or more of

B-grid by default. A street that meets none of the criteria in subsection B is on the B-grid.

A-grid frontages. A building or site element along an A-grid frontage must meet the form standard's A-grid calibration in the applicable table. The A-grid calibration carries the more intensive expression of the form standard — the lower maximum A-frontage setback, the higher minimum transparency, the stricter parking-placement requirement, the more demanding facade articulation standard.

B-grid frontages. A building or site element along a B-grid frontage must meet the form standard's B-grid calibration in the applicable table. The B-grid calibration provides defined relief from the A-grid calibration — typically a larger maximum A-frontage setback, a lower minimum transparency, or a less stringent parking-placement requirement.

Standards not modified by the grid. Standards that do not appear in the tables in two calibrations — standards stated as a single value, such as the minimum walk width for a single-door entrance — are not modified by the grid layer and apply uniformly along both A-grid and B-grid frontages.

Multi-frontage lots. A lot with A-grid frontage on one street and B-grid frontage on another street must meet the A-grid calibration along the A-grid frontage and the B-grid calibration along the B-grid frontage. The two frontages do not combine into a single calibration.

Grid amendments after adoption. A change to the grid layer is recorded through the zoning map amendment procedure in Chapter 3 (Section 11-3-16). The amendment application is evaluated against the criteria in subsection B.

Application. This section applies to a lot in a CMX, IMX, or SP district that shares a common lot line with a lot in an RMX district, and to a lot in an IMX or SP district that shares a common lot line with a lot in a CMX district. The standards in this section apply to the lot in the higher-intensity district and are in addition to the form, dimensional, and site design standards otherwise applicable.

Common lot-line setback at less-intense district abuttance. The minimum setback from the common lot line in the per-district table replaces the otherwise-applicable common-lot-line setback in the higher-intensity district's calibration. The setback is calibrated as a function of the intensity difference between the two districts.

Upper-story step-down. Where the higher-intensity district allows building heights that exceed the lower-intensity district's height limit, the portion of the building above the lower-intensity district's height limit must step back from the common lot line. The step-back is calibrated per additional story above the lower-intensity district's height limit.

Buffer yard. A buffer yard meeting the dimensions in the per-district table is required along the common lot line. The buffer yard is measured from the common lot line into the higher-intensity site and is exclusive of any parking, loading, storage, mechanical equipment, dumpster, or vehicular drive area.

Screening of parking, loading, and storage. Where surface parking, loading docks or loading areas, outdoor storage, or vehicular drive areas on the higher-intensity site face the common lot line, a continuous opaque screen at least six feet high is required along the common lot line. The screen may be a solid wall, a solid fence, an opaque planting strip of evergreen materials that achieves the opacity standard at maturity, or a combination. The screen is in addition to the buffer yard required by subsection D.

Screening of mechanical equipment, dumpsters, and outdoor service areas. Mechanical equipment, dumpsters, and outdoor service areas on the higher-intensity site are screened from view from the common lot line and from any abutting public right-of-way by a solid wall, a solid fence, or a building element of compatible material.

Lighting spillover. Lighting on the higher-intensity site is shielded such that no direct light source is visible from a window on the abutting lower-intensity lot, and the illumination at the common lot line does not exceed the threshold stated in the per-district table.

Vehicular access. A driveway or other vehicular access on the higher-intensity site may not cross the common lot line to take access through the lower-intensity district.

Calibration. The per-district values for the standards in this section are in Table 4-H.

Modification through compliance options. Several form standards in this chapter offer alternative compliance paths in the standard itself — 'must meet X or, where Y, must meet Z' — as built-in options that provide flexibility without a variance. A development that complies with a stated alternative compliance path is in compliance with the standard, without need for further review beyond the zoning compliance permit.

Variance. A development that cannot comply with a standard in this chapter through a stated compliance path may request a variance under Section 11-3-10 (zoning variance) of Chapter 3. The variance is administered under 76-25-502, MCA, by the Planning Administrator.

Variance criteria. The variance criteria are those stated in Section 11-3-10(E): the standard creates a practical difficulty or unnecessary hardship arising from a unique condition of the site, not of general application; the variance is the minimum necessary; the variance does not impair the purposes of this UDO or the standards of Title 76, chapter 25, MCA; and the variance does not adversely affect adjacent property or the public health, safety, or welfare.

Substantial-compliance posture. The standards in this chapter are objective standards. The substantial-compliance review under 76-25-304(2)(c), where it applies to a development reviewed under this chapter, is satisfied by demonstrating compliance with each applicable objective standard. The substantial-compliance review is not a discretionary determination separate from the objective-standard application; the chapter-25 ministerial-permit framing means that meeting the objective standards is meeting the substantial-compliance standard.