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
Founded in 1969 and located in West Palm Beach, FL, NACORE has 3,273 members. Its members consist of anyone managing, administering and/or operating regional real estate departments for ...
The arrangement of the walls and rooms in a structure. A two-dimensional horizontal scale drawing of the arrangements, size, and orientation of doors, rooms, walls, and windows of a single ...
There’s a time when it’s neither a Buyer’s Market nor a Seller’s Market. We call it “Renter’s Market”. It’s that time where, despite ...
Method of construction where vertical siding is attached to a horizontal framing structure. Often found in the design of agricultural buildings. ...
Some real estate sales require court confirmation of purchase to protect heirs and debtors from financial wrongs. These sellers have to sell their property due to unique circumstances. They ...
Wondering what “de facto” means? Well, because it’s a Latin word, let’s give a formal definition. De facto is Latin for indeed, in fact, in reality, actually. An ...
Expenditures incurred to initially purchase property, including incidental costs necessary to put the property into existing use and location. This cost is then depreciated over the assets ...
Right to peaceful enjoyment of property while the legal title is held by one person and the property is used by another. ...
Securing lease commitments to a building prior to its being available for occupancy. For example, a developer offers a discounted lease to potential tenants providing they agree to sign a ...

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