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Boston City Zoning Code

ARTICLE 31

SKYLINE DISTRICTS

Section 31-1.- Purpose of Skyline Districts

Skyline Districts are urban centers that serve the diverse needs of residents, employees, and visitors. The purpose of these districts is to support job growth, new housing, and entertainment and cultural destinations near the major transportation hubs and employment centers of the larger region. These high-activity areas support a vibrant mix of uses and densities while encouraging the preservation of historic areas. Skyline districts and their purposes are listed in this Section 31-1:

A.

The SKY-LOW District is distinguished by areas of cohesive historic buildings dating to prior eras of downtown with finer-grained parcelization and smaller building sizes near job centers and housing growth. These districts are regulated to advance historic preservation and ensure that new development is compatible with existing buildings in scale.

B.

The SKY District is distinguished by the city's most significant job, housing, and entertainment density and accommodates future growth near major transportation assets. These districts are regulated to ensure that new development enhances the urban vitality of the city and the public realm.

(Text Amd. No. 489, § 1, 10-28-2025)

Section 31-2. - Establishment of Skyline Districts.

A.

This Section 31-2, together with Section 3-1 (Establishment of Zoning Districts) establishes two Skyline Districts (SKY and SKY-LOW). A Skyline District is indicated by the designation "SKY" and "SKY-LOW" on any official zoning map of the City of Boston. The provisions of this Article 31 and the remainder of this Code constitute the zoning regulations in a Skyline District. Unless otherwise specified in this Article, where conflicts exist between a provision of this Article 31 and the remainder of this Code, the provision of this Article 31 shall govern. Where a conflict exists between a provision of this Article 31 and an overlay district, the terms of Art. 3-1A shall govern which provision shall take precedence.

B.

Use Regulations Applicable in Skyline Districts. Use regulations for Skyline districts are set forth in Article 8 (Uses) of this code. Additional use and performance standards are set forth in Table A of this Article 31.

C.

Dimensional Regulations Applicable in Skyline Districts. Dimensional Regulations for Skyline districts are set forth in Table B and modified by Section 31-3 and Table C as applicable.

D.

Parking and Loading Regulations Applicable in Skyline Districts. Parking regulations for Skyline districts are set forth in Article 23 (Off-Street Parking). Loading regulations for Skyline districts are set forth in Article 24 (Off-Street Loading).

E.

Prohibition of Planned Development Areas. Within the Skyline districts, Planned Development Areas ("PDA") shall be prohibited, except as expressly provided for in Section 31-6.

(Text Amd. No. 489, § 1, 10-28-2025)

Section 31-3. - Provisions for Design Review in Sky-Low District.

Any Proposed Project for the erection or extension of one or more buildings that results in the addition of an aggregate Gross Floor Area of twenty thousand (20,000) or more square feet located in a Sky-Low district shall be subject to: Subsection (a)(i) (Design Review Required by Applicable Zoning) of Section 80E-2.1 (Applicability of Small Project Review: Design Component), notwithstanding any contrary provision of Section 80E-2.1.

(Text Amd. No. 489, § 1, 10-28-2025)

Section 31-4. - Additional Provisions for Existing Buildings and Uses in Skyline Districts.

A.

Reconstruction and Extension of Nonconforming Buildings. Notwithstanding the provisions of Section 9-1 Reconstruction and Extension of Nonconforming Buildings, a Proposed Project may alter or enlarge a building that exists on the effective date of this Article and that does not conform to the applicable dimensional requirements specified in other provisions of this article, provided that such nonconformity is not increased and that any enlargement itself conforms to such dimensional requirements.

B.

Reconstruction and Extension of Nonconforming Uses. Notwithstanding the provisions of Section 9-1 Extension of Nonconforming Uses, a Proposed Project may result in the extension or conversion of a lawfully-existing Office use provided such extension or conversion results in the addition of less than 250,000 Gross Floor Area of Office use; and the extension or conversion of a lawfully-existing Hotel (Large) use provided such extension or conversion results in the addition of less than 50,000 Gross Floor Area or less than 50 guest rooms.

(Text Amd. No. 489, § 1, 10-28-2025)

TABLE A: ADDITIONAL USE AND PERFORMANCE STANDARDS

USE AND PERFORMANCE STANDARDS SKY-LOW SKY
STANDARDS FOR COMMERCIAL USES
Adult Entertainment Forbidden Conditional; Allowed within Adult Entertainment District, established pursuant to Section 3-1A by Map Amendment No. 130.
Office - Extra-Large Conditional until January 1, 2030; after which date Allowed, unless before such date the Zoning Commission votes to continue such conditional use, after evaluating the ongoing impact on downtown's vitality, impacts of office-to-residential conversion, and the city's need for mixed-use growth focused on housing.
Allowed for any Office - Extra-Large use lawfully existing on September 1, 2025.
Conditional until January 1, 2030; after which date Allowed, unless before such date the Zoning Commission votes to continue such conditional use, after evaluating the ongoing impact on downtown's vitality, impacts of office-to-residential conversion, and the city's need for mixed-use growth focused on housing.
Allowed for any Office - Extra-Large use lawfully existing on September 1, 2025.
STANDARDS FOR RESIDENTIAL USES
Ground Floor Dwelling Units Allowed No
STANDARDS FOR TRANSPORTATION USES
Standalone Parking Garage An allowed use or approved conditional use that is not a Transportation Use must be located on the ground floor of the building along any lot frontage that abuts a public sidewalk, street, or park to a minimum Ground Floor Use Depth of 25';
Subject to the provisions of Boston Air Pollution Control Commission Article 1: Downtown Parking Freeze
Accessory Parking, Shared Parking Subject to the provisions of Boston Air Pollution Control Commission Article 1: Downtown Parking Freeze
STANDARDS FOR INDUSTRIAL AND STORAGE USES
Food and Beverage Production Must include a minimum of 500 sf of accessory or associated Restaurant or Retail use Must include a minimum of 1,000 sf of accessory or associated Restaurant or Retail use

 

(Text Amd. No. 489, § 1, 10-28-2025)

TABLE B: DIMENSIONAL REGULATIONS

BUILDING LOT STANDARDS SKY-LOW SKY
Building Lot Coverage (max)
Lot Area less than or equal to 25,000 sf 95% 95%
Lot Area greater than 25,000 sf 90% 85%
Ground Floor Outdoor Amenity Space (min)
Located along the Primary Lot Frontage for Lot Area less than 25,000 sf 0% 0%
Located along the Primary Lot Frontage for Lot Area greater than 25,000 sf 5% 4 10% 4
Front Yard (min) 0'
Rear Yard (min)
With a party wall 0'
Without a party wall 5' 5
Side Yard (min)
With a party wall 0'
Without a party wall 5' 4
Building Height in feet (max) See TABLE C, Skyline Historic Dimensional Overlay Such height as complies with State Shadow Regulations specified in Article 2, or such height as complies with FAA and Massport critical airspace maps and processes to determine maximum height, whichever is lesser. 1 2 3
Stepback Height
Abutting a Lot containing a non-Historic Building 155' 6
Abutting a Lot containing a Historic Building Building Height of abutting Historic Building or, in the case of multiple abutting Historic Buildings, the lowest Building Height of the lowest such Historic Building. 6
Reduction (min) of Building Floor Plate area of all Building Floor Plates at and above Stepback Height - For a Building with any Building Floor Plate greater than 12,000 sf, the average of all Building Floor Plates located above the Stepback Height must be reduced by a minimum of 20% from the average area of all Building Floor Plates below the Stepback Height.
Length of building facade (max) at and above Stepback Height - Any building facade located at or above the Stepback Height must be less than or equal to 200' in length. 7
Building Floor Plate (max sf) at and above Stepback Height - 35,000
Blank Wall of Facade (max) 15' 20'
Ground Floor Height (min) 14'
Multiple Buildings Allowed Per Lot Yes

 

Footnotes to Table B.

1.

Structures built within the boundaries of the Midtown Shadow Overlay, as shown on Map 1A, shall comply with the provisions for the Midtown Cultural District set forth in the State Shadow Regulations; or such height as complies with FAA and Massport critical airspace maps and processes to determine maximum Building Height, whichever is lesser.

2.

The maximum Building Height for a Proposed Project with Lot Frontage along Washington Street with less than 60% of Gross Floor Area of Residential Use is limited to 200'.

3.

The maximum Building Height for a Proposed Project with Lot Frontage along Washington Street with more than 60% Gross Floor Area of Residential Use and only one Lot Line abutting another Lot within the SKY District is limited to 500', or such height as complies with the State Shadow Regulations, whichever is lesser. For the applicability of this footnote a Lot that would abut a Proposed Project if not divided by a public right of way shall be considered an abutting Lot.

For any Proposed Project that is subject to or has elected to comply with Large Project Review or Small Project Review under the provisions of Article 80, the following provisions shall apply:

4.

The required Ground Floor Outdoor Amenity Space may be located along any Lot Frontage shall be as determined through such review process.

5.

The minimum Yard may be 0' if it is determined through such review process that there is adequate and enduring separation between buildings abutting a Side or Rear Lot Line.

6.

Stepback Height may be determined through such review process provided there is adequate separation of tall building elements and improved building design to minimize impacts and any excessive wind downdrafts on significant public streets, sidewalks, and abutting structures.

7.

The maximum length of Building facade may be determined through such review process provided there is improved building design to minimize impacts on significant public streets, sidewalks, and abutting structures.

(Text Amd. No. 489, § 1, 10-28-2025)

Section 31-5. - Establishment of Skyline Historic Dimensional Overlays.

This Section 31-5, establishes Skyline Historic Dimensional Overlays as overlays to SKY-LOW in order to set height and building floor plate standards that help maintain the scale and historic character of existing areas within SKY-LOW districts. A Skyline Historic Dimensional Overlay is indicated by the designation "SKY-LOW-DT" on any official zoning map of the City of Boston. The provisions of this Section 31-4 are in addition to the requirements of Table B Dimensional Regulations.

The following Skyline Historic Dimensional Overlays are established:

A.

Downtown (SKY-LOW-DT): The Downtown Historic Dimensional Overlay includes the following two areas:

a.

Ladder Blocks: The Ladder Blocks are an architecturally- and historically-significant area of Downtown. Connecting Downtown and the Boston Common, the Ladder Blocks have a rich mix of notable 18th- and 19th- century buildings. Bounded by Washington and Tremont Streets, the area is named for the cross streets that create a street grid resembling a ladder.

b.

India and Broad Street Area: This area of the larger Wharf District is distinguished by its small urban fabric and mix of historic brick and masonry structures.

A Proposed Project within any such overlay shall comply with the Dimensional Regulations applicable set forth in Table B, as modified by Table C, of this Article 31.

(Text Amd. No. 489, § 1, 10-28-2025)

TABLE C: SKYLINE HISTORIC DIMENSIONAL OVERLAYS

HISTORIC DIMENSIONAL OVERLAY Height in feet (max) Building Floor Plate (max sf)
(SKY-LOW-DT) Downtown 1 155', or such height that complies with State Shadow Regulations, whichever is lesser. 1 25,000

 

Footnotes to Table C

1.

Structures built within the boundaries of the Midtown Shadow Overlay, as shown on Map 1A, shall comply with the provisions for the Midtown Cultural District set forth in the State Shadow Regulations.

(Text Amd. No. 489, § 1, 10-28-2025)

Section 31-6. - - Establishment of Areas within which a Planned Development Area May Be Permitted.

This Section 31-6, establishes areas within which Planned Development Areas (PDA), as described in Section 3.2.E, may be permitted within the Skyline Districts and sets forth applicable development criteria specific to Skyline Districts. For additional approval standards for Planned Development Area Development Plans, see Section 80C-4 (Standards for Planned Development Area Review Approval).

A.

Regulations for PDAs in SKY-LOW-DT. Planned Development Areas are permitted in the SKY-LOW-DT and shall include at least one Landmark. The purpose of establishing SKY-LOW-DT as an area in which a PDA may be permitted is to provide a more flexible zoning regulation; to provide public benefits to the City of Boston; and to encourage strategic development and housing growth that protects and enhances the historic character and buildings, Landmarks, and vitality of areas within the Downtown Historic Dimensional Overlay.

a.

Use Regulations. A Proposed Project within a PDA shall comply with the use regulations of the underlying zoning district, except as those regulations are expressly modified by an approved Development Plan. At least 60% of the Gross Floor Area of such an approved Development Plan shall be a Residential Use.

b.

Dimensional Regulations. The dimensional regulations of a Proposed Project within a PDA shall be as set forth in the applicable approved Development Plan.

c.

Requirement for Investment in Landmark(s) and Historic Buildings. A Development Plan shall include investment in the Landmark(s) and Historic Buildings within the PDA. Such investment shall provide physical improvements that exceed routine maintenance and are necessary to restore, preserve, or adapt the structure for continued or new use and long-term preservation. Any physical improvements to a Landmark shall be subject to review and approval by the Boston Landmarks Commission.

d.

Recommendation of the Office of Historic Preservation. The Director of the Office of Historic Preservation, or its successor agency, shall review and provide a recommendation to the Boston Redevelopment Authority on any Proposed Project within a PDA proposed in conformance with this Section 31-6.

B.

Regulations for Existing PDAs in SKY or SKY-LOW. A PDA may be permitted in SKY or SKY-LOW if it is in existence on the effective date of this Article 31.

a.

The approved Development Plan for such PDA may only be amended in accordance with Section 80C-7 (Amendment of Planned Development Area Plans) of the Code. Any proposed amendment may increase the maximum Building Height allowed in such approved PDA by no more than fifteen (15) feet, and such approved PDA as so modified shall supersede any contrary provision for maximum Building Height in this Article 31.

(Text Amd. No. 489, § 1, 10-28-2025)