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

A lender can be a private individual, a private or public group, or an institution that loans funds to a person or business that the lendee would later repay with interest in most cases. In ...

To pass property by will to an heir. Strictly speaking, real estate cannot be bequeathed to an heir, it must be devised. However, if it becomes clear the purpose of the testator was to ...

The term lock-in clause is used in an agreement that prescribes a period of time within which either of the parties that signed a contract cannot terminate the contract. In case one of the ...

Arrangement whereby a party providing financing gets a portion of the ownership. ...

Average of income, retail revenue, and population of a locality as a percentage of the entire United States. It reflects the economic status of a particular region. ...

For real estate investors, the vacancy and credit loss is a way to determine a property’s potential for profit. This value is determined by subtracting the losses brought by vacant ...

Payment received after the due date. A penalty and/or interest may be charged on such payment. For example, a bank may charge a penalty of $25 if a mortgage payment is received after the ...

Drain facility usually underground for waste and water disposal consisting on connected pipes. ...

Regulation of the Securities and Exchange Commission (SEC) establishing the criteria to avoid a private offering. For example, John wants to sell shares in an apartment house to several ...

Popular Real Estate Questions