Central Business District (CBD)

Overview

A Central Business District is the densest commercial tier in a city's zoning code, applied to the downtown core where high-rise office, hotel, and residential towers concentrate. CBD districts are typically FAR-driven rather than dwelling-unit-density-driven, allow the tallest as-of-right heights in the city, set the smallest (often zero) setbacks, and frequently waive parking minimums entirely. They are also where the most idiosyncratic local controls live: height districts (Boston's PDA, the federal Height Act in DC), view-corridor protections, and TDR (transferable development rights) programs that move FAR between parcels. Most cities pair the base CBD district with a downtown overlay (see district-downtown-cbd) that layers design review, ground-floor active-use, and incentive-zoning bonuses on top. Sub-types are common: B-5, CBD-1, CBD-2, Core, CD-1, DD.

Key characteristics

FAR-driven envelope — base FAR plus bonus FAR from incentive zoning is the controlling metric, not lot coverage or dwelling-unit density
Tallest as-of-right heights in the city, sometimes unlimited subject to FAA Part 77 and local height-district caps
Setbacks at or near zero — buildings typically meet the property line, build-to lines common
Parking minimums frequently waived; some CBDs impose parking maximums instead
Ground-floor active-use mandates (retail / lobby / restaurant) along designated frontages
Often paired with a downtown overlay carrying design review and incentive bonuses
Sub-types (B-5, CBD-1, CBD-2, Core, CD-1) calibrate FAR and height by sub-zone

How it appears in zoning

As the base district covering a city's downtown core on the zoning map ("CBD", "B-5", "CD-1", "DD")
As a height district overlay (Boston PDA, DC Height Act zones) layered on top of the base CBD
As the receiving zone in a TDR program that moves FAR from landmarks or view-corridor parcels
As the target district for office-to-residential conversion incentives (NYC, San Francisco, LA)
As a federal monumental-zone sub-area (DC Capitol corridor, federal building precincts)

Why it matters

CBD zoning is where the biggest deals land — it's the only district in most cities where high-rise office, downtown residential towers, and full-block mixed-use are by-right. The post-COVID office vacancy wave has made it the focus of conversion-incentive programs (NYC AB 6770, CA AB 2011, San Francisco's downtown conversion ordinance), which often layer additional bonuses on top of the base CBD envelope. Feasibility teams should treat CBD parcels as multi-layer problems: base FAR, height district, TDR availability, overlay bonuses, and federal monumental controls can all stack on a single site.

Watch items

Height districts (Boston PDA, DC Height Act, view corridors) can cap heights well below the base CBD limit — read the height-district map separately
TDR programs change the math — base FAR may be only half the achievable FAR if receiving-zone rights are available
Office-to-residential conversion programs (NYC AB 6770, CA AB 2011, SF downtown ordinance) add a parallel by-right path with different bonus stacks — confirm program eligibility
Federal monumental zones (DC Capitol corridor, federal precincts) can impose absolute height and design controls outside the local code
Ground-floor active-use mandates are nearly universal in CBDs — residential lobbies often don't satisfy the requirement
Parking maximums (not just waived minimums) appear in some CBDs — verify before assuming structured parking is allowed at any ratio