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Zoning Glossary

Below is a quick reference guide for commonly used zoning terms. For a full list of definitions, click here.

Accessory Use or Structure

A use or structure which is customarily incidental to the principal use or structure, serving no other use or structure, and which is subordinate in area, intensity and purpose to the principal use or structure. An accessory use or accessory structure shall be located on the same lot or parcel as the principal use or structure, except where it is otherwise allowed in these Zoning Regulations.

Adjoining Property

Land which is touching or would be touching in the absence of an intervening utility or road right-of-way, other than a principal arterial highway.         

Age-Restricted Adult Housing

A development that contains independent dwelling units, each with a full kitchen that is designed for and restricted to occupancy by households having at least one member who is 55 years of age or older. An exception is allowed for up to five years following the death or departure, due to incapacity, of a household member 55 years or older, provided a surviving household member who is at least 50 years old continues to live in the unit. Children less than 18 years of age shall not reside in a dwelling unit for more than a total of 90 days per calendar year. Age-restricted adult housing may include accessory structures or uses for the residents, such as social, recreational or educational facilities and housekeeping, security, transportation or personal services.         

Agricultural Land Preservation Easement

An easement held by the Maryland Agricultural Land Preservation Foundation or the Howard County Agricultural Land Preservation Program.         

Agritourism Enterprise

Activities conducted on a farm and offered to the public or to invited groups for the purpose of recreation, education or active involvement in the farm operation. These activities must be related to agriculture or natural resources and incidental to the primary operation on the site. This term includes farm tours, farm stays, hay rides, corn mazes, classes related to agricultural products or skills, picnic and party facilities offered in conjunction with the above, and similar uses.         


A private street which provides access to the side or rear of two or more lots for service functions such as loading or deliveries, trash pick-up, or parking areas.         


Agricultural Land Preservation Program.         

Amenity Area

A usable outdoor landscaped or hardscaped area such as a plaza, courtyard, garden or similar area which is designed to be open to and used by the public, and to be easily accessible.         


A roofed passageway, the design and construction of which matches the design and construction of the principal structure, for the purpose of connecting the principal structure to another building or structure.         


A structure with exterior walls and a roof which combine to form a structure used for the occupancy or activities of persons, for the shelter of animals, or for the storage or protection of objects, including but not limited to apartments, barns, dwellings, garages, hotels, offices, restaurants and stores. Signs are not to be considered a building, or part of a building, and are regulated by the Howard County Code.         

Building Height

The vertical distance from the mean elevation of the lowest and highest elevation points at grade adjoining the exterior walls of the building to the highest point of a flat roof; to the deck line of a mansard roof; and to the mean height between the eave and ridge of the highest roof section for a gable, hip or gambrel roof. Where the grade has been artificially raised above the natural or surrounding finished grade, the vertical distance will be measured by projecting the natural or surrounding finished grade onto the foundation wall.         

Building Restriction Line (BRL)

A line established on a lot to indicate the minimum structure setbacks required by the Zoning Regulations for the zoning district in which the lot is located or the setbacks required by the Subdivision and Land Development Regulations, if more restrictive.         

Cluster Exchange Option

One of two options for transferring density from a sending parcel in the DEO Overlay District. The cluster exchange option allows density to be transferred from a qualifying sending parcel at a maximum rate of one development right per 4.25 gross acres of area within the sending parcel.

Cluster Subdivision

A type of subdivision allowed in the RC and RR Zoning Districts and consisting of cluster lots and a preserved area. The preserved area is the residual area of the parcel being subdivided and consists of one or more preservation parcels.         

Commercial Use

Any use involving in part or in whole the sale or rental of merchandise, materials or services, but not including home occupations as defined in this section.         

Conditional Uses

Land uses and activities which require approval by the Hearing Authority for a specific location and site plan, based upon standards established in these Zoning Regulations. Formerly called special exceptions.         


The number of principal dwelling units per unit of land area. Accessory dwelling units such as farm tenant houses, caretaker dwellings and accessory apartments are not included when calculating density.         

Density Exchange Option

One of two options for transferring density from a sending parcel in the DEO Overlay District. The Density Exchange Option allows density to be transferred from a qualifying sending parcel at a maximum rate of one development right per three gross acres of area within the sending parcel.         

Depth of Lot

The mean horizontal distance between the front line and rear lot line of a lot.         

Detached Building

A building surrounded by yards or other open area on the same lot.         

Develop or Development

This term refers to the establishment of a principal use on a site; a change in a principal use of a site; or the improvement or alteration of a site by construction, enlargement, or relocation of a structure, the provision of storm water management or roads, the grading of existing topography, the clearing or grubbing of existing vegetation, or any other non-agricultural activity that results in a change in existing site conditions.         


A building, or portion thereof, which provides living facilities for one family. As used herein, the term "dwelling," or any combination thereof, shall not be deemed to include a hotel, motel, clubhouse, hospital or other accommodations used for more or less transient occupancy.         

Dwelling, Temporary Accessory Family

A Conditional Use category for a second dwelling unit on a lot which is used for the housing of an elderly or disabled family member of the resident of the principal dwelling unit and which complies with the requirements of Section 131.0.N. A temporary accessory family dwelling shall either be a removable modular building designed for this purpose or an alteration of an existing accessory building. A temporary accessory family dwelling shall not be a newly constructed building.         

Dwelling, Apartment

A dwelling in a building containing three or more dwelling units separated by both vertical and horizontal party walls.         

Dwelling, Manufactured

This term has the same meaning as "Mobile Home".         

Dwelling, Multi-Family

This term includes apartments, whether rental units or condominiums, and single-family attached dwellings.         

Dwelling, Multi-Plex

A dwelling unit in a multi-plex dwelling unit building that resembles a large, single-family detached dwelling, but is divided internally into three or four units. The dwelling units are separated by party walls, but are not arranged in line and the party walls are not parallel to each other. The dwellings may have a shared or separate exterior entrance.         

Dwelling, Single-family Attached

One of a series of two or more dwelling units, separated either by vertical or horizontal party walls, with each unit having its own separate exterior entrance(s).         

Dwelling, Single-family Detached

A building arranged or designed for use as a principal dwelling, and entirely separated from any other principal building by open area on all sides.         

Dwelling, Single-family Semi-Detached

One of two attached dwelling units located on abutting lots, separated by one vertical party wall without openings extending from the basement floor to roof along the dividing lot line, with each unit having its own exterior entrance and its own adjacent ground level outdoor area for the exclusive use of its occupants.         

Dwelling, Two-family

A building which contains two dwelling units, of which neither is an accessory apartment, and which is arranged, designed or used for occupancy by two families. The dwelling units in a two-family dwelling are not separated by an attached garage or by an open or enclosed breezeway.
(See also the definition of Dwelling, Accessory Apartment.)         

Dwelling, Zero Lot Line

A single-family detached dwelling unit located with one side less than seven and a half feet from one side lot line and designed to orient interior space to the other three yards.         


A lot or parcel of land used for farming that is 3.0 acres or larger.         

Farm Brewery

An agricultural processing facility located on a farm with equipment, components and supplies for the processing, production and packaging of beer, ale, porter, stout and similar malt-based or grain based beverages on the premises. Farm brewer activities may include associated cooking, fermenting, bottling, storage, aging, shipping, receiving, and may also include accessory facilities for laboratory work, maintenance, and office functions.          Class 1A: A farm brewery which includes product tasting, product sales, site tours, and educational programs.

Farm Tenant House

An accessory detached building or mobile home that is:

a. Designed and arranged for use as a dwelling;

b. Located on a parcel of land used for farming; and

c. Occupied by at least one person who is employed by the owner or operator of the farm on which the dwelling is located to engage in farming on a full-time or part-time basis.

Farm Winery

An agricultural processing facility located on a farm with a vineyard, orchard, hives, or similar area, which consists of vinification equipment, components and supplies for the processing, production and packaging of wine and similar fermented beverages on the premises. Farm winery activities may include associated crushing, fermenting and refermenting, distilling, blending, bottling, storage, aging, shipping, receiving, and may also include accessory facilities for laboratory work, maintenance, and office functions.

Class 1A : A Farm Winery which operates for purposes of wine tasting, wine sales, tours, educational programs, meetings and social events.         

Class 1B : A Class 1A Farm Winery that requires approval as a Conditional Use.

Class 2 : A Farm Winery which operates on at least 25 acres for the purposes of wine tasting, wine sales, tours, educational programs, meetings, social events and special events.         

Final Development Plan

A drawing or series of drawings, at an appropriate scale, covering the same geographical area covered by the Comprehensive Sketch Plan or a portion thereof indicating the various land use areas with criteria which shall be the same as those approved by the Planning Board as part of the Comprehensive Sketch Plan, and intended for recordation among the Land Records of Howard County, Maryland.         

Flex Space

A building that is designed with three or more modular bays to accommodate businesses of varying sizes, with the modular bays capable of being used for a variety of uses, including offices, research and development, light manufacturing, service agencies, and accessory storage and sales, provided that the uses are limited to those uses permitted by the zoning district or final development plan in which the flex space is located. All principal activities of the various uses shall be conducted wholly within an enclosed building, but accessory outdoor storage may be conducted as permitted by these Regulations. Flex space buildings have rear loading.         

Floating District

A district of undetermined location which may only be placed on the zoning map upon petition of a property owner and not by government initiative. A floating district may only be applied to a specific property if stated criteria are satisfied, a finding of compatibility is made and a development plan is approved for the property. A finding of mistake in the existing zoning or a substantial change in the character of the neighborhood since the last Comprehensive Zoning Plan is not required to apply a floating zone to a property. The purpose statement of a district will specify whether the district is a floating zone.


That area which would be inundated by the storm water runoff equivalent to that which would occur from a rainfall of 100-year frequency, assuming total development of the watershed. Floodplain determination shall be in accordance with the Howard County Design Manual.         

Floor Area, Gross

The sum of the areas of the several floors of the structure(s) as measured by the exterior faces of the walls.         

Floor Area, NET

The sum of the areas of the areas of the several floors of the structure(s) as measured by the exterior faces of the walls, less any area within the structure(s) devoted to parking, vehicular driveways, atria, office building storage areas, or enclosed malls and similar areas.         

Floor Area Ratio (FAR)

The ratio of the gross floor area to the gross lot area.         


That portion of a lot or parcel of land which adjoins a public road that provides vehicular access to the property.         

General Plan

A plan for the County, approved by resolution of the County Council, which includes but is not limited to a plan for land use and land conservation and multi-year development plans for transportation, public facilities, water, sewerage, park land, housing, human services, historic preservation, and environmental protection.         

Gross Area

The entire area within a development project.         

Hearing Authority

Either the Board of Appeals or Hearing Examiner.         

Historic District

An area in the County which has significant historic or architectural value, the boundaries of which have been established in accordance with the provisions of Sections 100.0.G and 114.0 of these Zoning Regulations, or the previously established Ellicott City Historic District.         

Historic Structure

A structure or cluster of structures situated within the County which, together with its appurtenances and environmental setting, have significant historic or architectural value, and have been designated as such by resolution of the County Council.         

Illegal Use

Any use, whether of a structure or of a tract of land, in which a violation of any provision of these Zoning Regulations has been committed or exists, or any use which is not specifically permitted by these Regulations.         

Industrial Uses, Light

Uses engaged in the manufacture, predominately from previously prepared materials, of finished products or parts which may include the processing, fabrication, assembly, treatment, packing, accessory storage, or distribution of such products, and can include uses such as the manufacture of electronic or optical instruments, equipment and components, the preparation of food products, the manufacture of pharmaceutical products, and similar uses. The principal activities shall be conducted wholly within an enclosed building but accessory outdoor storage may be conducted as permitted by law. Light manufacturing uses do not include any manufacturing use permitted as a matter of right solely in the M-2 District.         

Institutional Use

A nonprofit or quasi-public use, such as a religious facility, library, public or private school, hospital, or government owned or government operated structure, or land used by or for similar purposes.

Lot or Parcel

A piece of land described on a Final Plat or in a deed and recorded in the Land Records of Howard County in accordance with the laws and regulations in effect at the time of recordation.

Lot Coverage

That portion of a lot which, when viewed directly from above, would be covered by a structure or any part of a structure.         

Lot Size, Maximum

Maximum: The largest lot area allowed under the bulk requirements of the applicable zoning district, calculated based on the gross area of the lot. The pipe stem area of pipe stem lots shall not be included for purposes of calculating the maximum lot size.         

Minimum : The smallest lot area allowed by the bulk regulations of the zoning district. The pipe stem area of pipe stem lots shall not be included in the required minimum lot size.         

Low Income Housing Unit

A dwelling unit offered for sale or rent to households with incomes below 50% of the median income in the Baltimore region.         

Mixed Use Development

A development including residential, nonresidential, and open space land uses which has been approved on a Preliminary Development Plan.         

Mobile Home

A dwelling unit that is fabricated in an off-site manufacturing facility for installation or assembly at the building site, which:

a. Bears a label certifying that it complies with the standards of the National Manufactured Housing Construction and Safety Standards Act of 1974 as promulgated by the U.S. Department of Housing and Urban Development (HUD); or

b. Was manufactured prior to the effective date of the National Manufactured Housing Construction and Safety Standards Act of 1974, is transportable in one or more sections, is built on a permanent chassis, and is designed to be used as a dwelling.

Moderate Income Housing Unit

A dwelling unit offered for sale or rent to households with incomes up to 80% of the median income in Howard County, in accordance with Title 13, Subtitle 4 of the Howard County Code and the Procedures of the Howard County Department of Housing and Community Development.         

Neighborhood Infill Subdivision or Resubdivision

Small subdivisions or resubdivisions which create four or fewer lots from R-20 or R-12 zoned land surrounded along 60% or more of the perimeter by recorded lots 20,000 square feet or greater (in R-20) or 12,000 square feet or greater (in R-12).         

Net Acre

An acre of land that includes no land in the 100-year floodplain and no steep slopes existing at the time of subdivision.         

Open Space

A separate lot or area which provides for protection of the environment, for recreation or for public use, including public facilities such as schools, libraries, fire stations and parks as shown on the General Plan or hiking, biking and equestrian trails. Parking areas may be included within open space if accessory to an open space use.         

Overlay District

A district established to respond to special features or conditions of a land area, such as historic value, physical characteristics, location, or other circumstances. An overlay district supplements or provides an alternative to the regulations of the underlying zoning district. The purpose statement and the title of a district will specify whether the district is an Overlay District.         

Parking Garage

A structure occupied by a public, community, commercial or private establishment providing space for the temporary storage of six or more automobiles and other vehicles, where service or repair facilities are not permitted. A parking garage shall not be used for the storage of dismantled or wrecked motor vehicles, parts thereof, or junk.         

Parking Lot

An open lot serving the functions defined for a parking garage.         

Personal Service Use

A commercial establishment in which the principal occupation is the repair, care, maintenance, styling, fashioning, or customizing of personal attributes that are a physical component of a person, or personal properties that are worn or carried about the person. Personal service establishment uses include such uses as barber shops, hair salons, nail salons, health spas, self-service laundromats, shoe cleaning or repair shops, and similar uses.         

Preservation Easement, County

An easement held by Howard County which has been established through one of the following:

a. The purchase of development rights by the Howard County Agricultural Land Preservation Program (ALPP Purchased Easement), or

b. The dedication of a preservation parcel to the Howard County Agricultural Land Preservation Program (ALPP Dedicated Easement), or

c. The dedication of a preservation parcel to an easement holder other than the ALPP (Other Dedicated Easement).

Preservation Parcel

A parcel in the RC or RR District that encompasses all or a portion of the preserved area of a cluster subdivision or receiving parcel subdivision, or that is designated as a sending parcel on a final plat of easement. A preservation parcel is encumbered by a preservation parcel easement and may be buildable or non-buildable depending on whether one of the housing units permitted by zoning will be located on the parcel.         

Preservation Parcel Easement

A permanent easement that prohibits a preservation parcel from subdivision and most types of development, as specified in the requirements for the RC and RR Districts.         

Principal Use or Structure

The main use of a lot or the structure used for the main function of a lot, as opposed to an accessory use or structure. Structures which are attached to the principal structure, either directly or by a breezeway not to exceed 15 feet in length, shall be considered part of the principal structure.         

Receiving Parcel

A parcel in the DEO Overlay District which receives development rights from a sending parcel, in accordance with the requirements of the DEO District, and as a result can be subdivided at a greater density than would otherwise be allowed in the underlying zoning district.         

Residential Zoning District

a. The RC, RR, R-ED, R-20, R-12, R-SC, R-SA-8, R-H-ED, R-A-15, R-APT, R-MH, R-SI, R-VH, and PSC Districts;

b. Residential land use areas of the NT and PGCC Districts as indicated by approved comprehensive sketch plans or, for areas where there is no approved comprehensive sketch plan, by the preliminary development plan;

c. Residential land use areas of a MXD District as indicated by approved preliminary development plans or, if there is no approved preliminary development plan, MXD-zoned land for which the underlying zoning district is one of the districts listed above in this definition.

d. Residential land use areas of a TOD, CAC, TNC or CCT District.

Right-of-Way, R.O.W.

A strip or parcel of land designated for use as a street, highway, driveway, alley or walkway, or for any drainage or public utility purpose or other similar uses. For public streets, the right-of-way width shall be as required by the State for State roads and the Howard County Design Manual for County Roads.         

Sending Parcel

A parcel in the DEO Overlay District from which development rights are removed and transferred to a receiving parcel in accordance with the requirements of the DEO District. A sending parcel is a type of preservation parcel and is subject to a preservation parcel easement.         


The distance between a structure or use and a boundary such as a lot line, project boundary, right-of-way line, or zoning district boundary. A setback is measured as the shortest horizontal distance between the project boundary and the nearest point of the use, structure or projection thereof. Where these Zoning Regulations require a minimum setback from a zoning district or right-of-way, and the property subject to the setback does not abut or adjoin the zoning district or right-of-way, the required setback is measured across the intervening properties. For lots that front directly on a public road, the setback is measured from the ultimate right-of-way of the public road as determined by the Howard County Design Manual Volume III, Roads and Bridges, or the State Highway Administration, Highway Needs Inventory.         

Site Development Plan

A plan prepared in accordance with the Subdivision and Land Development Regulations indicating the location of existing and proposed structures, paved areas, trails, walkways, vegetative cover, existing and proposed grades, initial landscaping, screening and other required items within a site proposed for development.         

Sketch Plan

A sketch indicating the general objectives and lay-out for development of a site. The basic role of the sketch plan is to allow the County to provide the developer with important information that may affect the project and to ensure that the plan complies with the Zoning Regulations and incorporates good planning and development principles.         


a. Any purpose for which a structure or a tract of land may be designed, arranged, intended, maintained or occupied; or

b. Any activity, occupation, business or operation carried on, or intended to be carried on, in a structure, or on a tract of land; except that, wells, septic systems and storm water management systems are not considered uses for purposes of these Zoning Regulations.

c. The term "permitted use" or its equivalent shall not be deemed to include any nonconforming use.


A grant of relief to a zoning regulation in a specific case concerning parking requirements or the bulk regulations for a zoning district or bulk regulations in the supplementary zoning district regulations, except that variances may not be granted for density requirements, or minimum or maximum lot size requirements. Variances are not applicable in any district for which bulk regulations are controlled by a Final Development Plan. Unless otherwise specified in the Zoning Regulations, variances are not applicable to requirements that are conditions for allowing a specific use. An Administrative Adjustment to bulk regulations is considered to be a type of variance.         

Village Center, New Town

A Mixed-Use Development in the New Town District which is in a location designated on the New Town Preliminary Development Plan as a "Village Center", which is designed to be a community focal point and gathering place for the surrounding village neighborhoods by including the following items:

a. An outdoor, public, village green, plaza or square, which has both hardscape and softscape elements. This public space shall be designed to function as an accessible, primarily pedestrian-oriented promenade connecting the various village center buildings and shall include public seating features;

b. Stores, shops, offices or other commercial uses which provide opportunities to fulfill the day-to-day needs of the village residents, such as food stores, specialty stores, service agencies, financial institutions, personal services, medical services, and restaurants;

c. Space for community uses and/or institutional uses; and

d. Residential uses, to the extent appropriate to support and enhance, but not overwhelm, other uses in the village center.

Zero Lot Line Development

A development of single-family detached units in which one or more units are located less than seven and one-half feet from a side lot line, but no less than 15 feet from the nearest structure on another lot.         

Zoning Maps

Maps incorporated into the provisions of these Zoning Regulations.

Zoning Permit

A document issued by the Howard County Department of Planning and Zoning authorizing an entity to begin certain activities or uses as required in Section 128.0 of these Zoning Regulations.         
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