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

Part of something such as the units making up a heating or air conditioning system in a building. ...

Payment made by the tenant to the landlord for the right to use property, such as an apartment or office. ...

See concrete block. ...

In short, an overage means a surplus or an excess of money. An overage can present itself at a property at an auction where the asset has gone over the asking price. Suppose there’s a ...

" A metal plate attached to the lower end of a door to prevent marring from people "kicking" the door in order to open it. A metal plate mounted on the open edge of a stairs platform." ...

Managing partner of a limited partnership who is in charge of its operations. A general partner has unlimited liability. Member of a partnership who is jointly and severally liable for ...

The abstraction method is a valuation procedure used to determine the land value relative to the total market value of the property. The abstraction approach is most often used when there ...

Performance of a complete inventory of real property within a jurisdiction. A cadastral program produces the cadastral map. ...

Depressed, poorly kept locality that may include vacant businesses. It may be a high crime area. The people living in the area are typically poor and there may also be homeless people. ...

Popular Real Estate Questions