Open Space Ratio
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%.
Popular Real Estate Terms
Land located next to water that has and will continue to experience water damage. The land generally is not suitable to build a structure on. In some cases, federal or local government may ...
The definition of in rem in real estate is a legal case against a property rather than a person. The legal application of in rem in real estate is most often seen when a homeowner defaults ...
Local governmental ordinance breaking down the country into districts that are restricted on how private property is to be constructed and used. It applies to the land and buildings. The ...
in masonry, the stones or bricks that are laid cross ways on a wall providing support to the horizontal stretcher bricks. The ends of the header bricks are visible in the wall. A beam ...
Founded in1934 and located in Chicago, IL with a 1993 membership of 8,300, the IAAO seeks to ameliorate assessment standards as well as to perform ongoing property assessment research. The ...
The definition of an open-end mortgage underlines the fact that the mortgage or trust deed can be increased by the mortgagee (borrower). The mortgagee may secure additional money from the ...
Real estate broker specializing in the listing and selling of commercial property. This property can include apartments, businesses, hotels, industrial, retail or wholesale uses. ...
Subordinate neighborhoods that are tied to an urban area economically. For example, office buildings in a city are the workplace for residents in surrounding communities. ...
Branch of economics that is concerned with the study of factors that explain, and policies that promote, regional economic growth and development. Regional economic factors affect ...

Have a question or comment?
We're here to help.