Definition of "Open space ratio"

Gena Taylor real estate agent

Written by

Gena Taylorelite badge icon

Coldwell Banker FI Grey & Son Residential Inc.

When talking about the open space ratio we are referring to a term that is used in zoning laws and regulations. The open space ratio is a term used to measure open space on a developed land or zoning lot. The open space ratio is calculated in the percentage of open space in the building's square footage. For example, a housing subdivision containing 100 acres has devoted 10 acres to open space. Therefore, the open space ratio is 1/10 or 10 percent (10/100). Or an office building of 10,000 square feet with an open space ratio of 20% will have 2,000 square feet designated to remain open space.

Open Space Ratio in Residential Real Estate

The term open space ratio is a concept that applies to residential developments, and it usually refers to commonly used open space. While not necessarily a way to determine the ratio of “green” open space on lots of land proposed for residential development. The term open space ratio can refer to two types of open space:

  • Allowable Areas

Allowable open space are the areas that are required common areas to be maintained and remain undeveloped for the benefit of those living or working on the lot parcel: parking lots, yard requirements, floodplains, recreational areas, stormwater management systems, etc.

  • Prohibited Areas

Prohibited open space areas are privately owned sites that are not accessible for those living or working on the lot parcel and that are also available for further structural developments.

How is Open Space Ratio Calculated?

The open space ratio is a zoning law used by municipalities to be able to control the types of buildings built, their height, and their ratio of open space. It is a means for municipalities to ensure that the open space available on a developed land makes up a certain percentage of the lot developed. In most cases, that requirement is of a 20% open space ratio.

Open Space Ratio Formula:

Open Space Ratio (OSR) = Commonly-owned Open Space / Total Area Proposed for Development


So if you have 12 acres available for residential development and you have 6 acres of commonly-owned open space (ponds, recreation area, parking area, buffers, etc) you will have an open space ratio of 50%.

image of a real estate dictionary page

Have a question or comment?

We're here to help.

*** Your email address will remain confidential.
 

 

Popular Real Estate Terms

Rentals received in cash rather than on credit. ...

Kind of siding for wood frame houses where the joints in the usually vertical siding are covered by narrow strips of wood called battens. The battens are nailed over the joints. ...

The Debt-to-Income Ratio’s (DTI) definition is a measure that allows one to compare the ability an individual has to afford a monthly debt payment out of their monthly gross income. ...

Husband's common law rights to the property his deceased wife owned either during the marriage or at the time of her death. The husband has life estate rights in the deceased wife's ...

Same as term government rectangular survey: Way in which the U.S. government uses to subdivide public land. Land is designated as either a base line (East-West) or principal meridian line ...

The amount of inherent risk for a mortgage in granting a mortgage. An operating principle in mortgage risk rating is that the mortgage cannot exceed 2.5 times the mortgagor's annual income, ...

Writ issued by a superior court to a lower court requiring the latter to produce a record of the proceedings of a particular case. The purpose of a writ of certiorari is to review the ...

Legal obligation to pay for a benefit received as if a contract has actually occurred. This may arise in a few cases so that an equitable situation occurs. An example is when a homeowner ...

Street terminating at one end with only one outlet. A dead end street is not a through street. See also cul de sac. ...

Popular Real Estate Questions