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
Goods that are freely substitutable. It is goods of a given class or type, any unit of which is as acceptable as another, and capable of satisfying an obligation expressed in terms of the ...
Individual who gives false statements under oath, which is a criminal act punishable by imprisonment and fine. An example is signing a tax return that fraudently understates rental income, ...
Roof having four triangular sides forming a point at the top of a pyramid. A pyramid roof is primarily used for steeples on top of churches or certain public buildings. ...
Also called all inclusive trust deed (AITD). A mortgage (trust deed) that encompasses existing mortgages and is subordinate to them. The existing mortgages stay on the property and the new ...
The term statute is a written law that is adopted by a legislative body from the country, federal, state, county, or city level. The statute definition can be a legislative written decree ...
An accessory building is an outdoor structure used by the occupants of the main building or house. They have different functions and can be detached or attached to the main building on the ...
Laws enacted by every state governing the activities and requirements of real estate salespeople and brokers. Upon satisfying the necessary age and residency requirements and satisfactorily ...
An individual appointed by a court to manage the affairs and property of a legally incompetent party. The conservator has full decision-making authority over the affairs of the property in ...
Land that has poor income potential, usually used in an agricultural sense meaning that the land is untellable, has poor access, is extremely steep, has suffered serious erosion, is ...

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