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
Assemblage in real estate is the process of combining multiple small plots of land into one larger plot. This is accompanied by plottage, which is the increase in value that occurs when ...
An upper limit on the interest rate that can be charged in a variable rate mortgage over its life. For example, a variable rate loan is initially offered at 7% loan rate, and its interest ...
Looking for an amortization definition? Amortization is an accounting term that basically means something like “reducing the gap between what is owed”. Here’s the play by ...
An individual, educated, trained, and licensed in the principles of designing structures, and rendering drawings, specifications, bidding requirements. ...
Those factors causing the movement of people, industry, and business from the central city to the outside central city areas, suburbs, and/or small cities. Elements of the dispersing force ...
Another residence in addition to the main residence where a person or family resides. An example is a second home out of the city used on weekends and during vacations. Interest and real ...
Lien which is over and above a first lien. A second lien is subordinate to the first lien and can be satisfied only after the initial lien is satisfied. ...
Projecting structure or part of a building. For example, a home was built with balconies jutting out from the sides of the building or a large rock formation constructed out into the ocean ...
An obligation of the owner of property that is recorded with his permission such as a mortgage. Encumbrance on property without being objected to by the owner. ...

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