The New York City Building Code and NY State Multiple Dwelling Law require that a living room must have at least one operable window. The window’s total surface area has to be at least 10% of the area of the room and the combined opening area at least 5% of the room square footage.
I am Jorge Fontan, an architect and owner of NYC based architecture firm Fontan Architecture. In this post I am going to discuss a few of the window requirements for living rooms in New York City.
NYC Building Code Window Requirements
The New York City building code requires operable windows for all “occupiable and habitable spaces.” The building code defines a habitable space as follows:
“All rooms and spaces within a dwelling unit in Group R or I-1, including bedrooms, living rooms, studies, recreation rooms, kitchens, dining rooms and other similar spaces”
I have another blog post going into more depth on the Definition of Habitable Space if you are interested.
Minimum Window Size for Living Rooms
“The minimum openable area to the outdoors shall be 5 percent of the floor area of the habitable space being ventilated. Every opening providing required natural ventilation shall be at least 12 square feet (1.1 m2) of glazed area, providing a minimum of 6 square feet (0.56 m2) of openable area”
The code requires that every window to qualify for natural light and air must be a minimum of 12 square feet per window. The window or windows (all together if more than one) must have a surface area of glass equal to 10% or more of the room floor area. When open, the windows (combined) must have an opening equal to 5% or more of the room floor area.
Any window under 12 square feet would not count for this calculation.
Lot Line Windows Do Not Count for Light and Air
Lot line windows (without an easement) do not qualify for natural light and air. These are windows located on a shared property line with another building. In many zoning districts windows within 30 feet of and facing a shared lot lines do not count either.
Verification of Windows
As an architect, whenever we submit plans to the NYC Department of Buildings for new residential buildings or any alteration to existing residences, we must provide natural light and air calculations for all habitable rooms within a house or apartment. Any space that does not have sufficient light and air would be in violation of the building code.
Why Natural Light and Air are Required
In 1901 New York City passed the New Law Tenement Act which was the first building code in New York to require an outside window to all rooms within residences. This was done for health reasons. They found higher rates of illness in people living within apartments that had insufficient light and air. This law exists to protect the people’s physical and mental health.
Can You Have a Living Room With No Windows
It is illegal to have a living room with no windows. Living rooms require windows by code to provide natural light and air. This is standard throughout the United States and many other parts of the world. Chapter 12 of the International Building Code outlines this requirement. Many states and cities have their own codes that further detail this regulation such as the New York State Multiple Dwelling Law and New York City Building Code.
Can You Have an Interior Window Through a Wall to a Room With a Window
Having a window on an interior wall connecting to a room with a window does not count for natural light and air. These types of windows were called “Tuberculosis Windows” and were later banned in the New Law Tenement Act of 1901. These windows were common in NYC after the 1850s to allow for cross ventilation, but the 1901 code requires all rooms to have a window opening directly to the outdoors.
How To Calculate Natural Light And Air
In the picture below you can see a loft apartment we worked on. In this loft there are many large windows and a large living room. To perform the light and air calculation, you determine the floor area of the living room. You then figure out 10 percent of this area. That is the requirement for all the windows added up for natural light. As previously stated, any window under 12 square feet is not counted for this calculation.
To calculate the required natural air, you perform the same calculation but you use a factor of 5% for natural ventilation. This is once again the total aggregate area of all the window openings in the room. The 10% of natural light and 5% of natural ventilation requirements are minimums. You are more than welcome to exceed this but cannot have less.
Natural Light and Air Requirements
Providing natural light and natural ventilation to all habitable rooms in an apartment is not only important for physical and mental health but is also a requirement by law. An architect must verify that these specific requirements are met in all residential spaces within New York City.
Thank You for Reading Our Blog Post Explaining Required Windows for Living Rooms in NYC
I hope this was helpful. If you would like to speak with an architect about a potential project, you can contact us at Fontan Architecture directly.
This post was written by Jorge Fontan AIA a Registered Architect and owner of New York City architecture firm Fontan Architecture. Jorge Fontan has earned 3 degrees in the study of architecture including two degrees from the City University of New York and a Masters Degree in Advanced Architectural Design from Columbia University. Jorge has a background in construction and has been practicing architecture for 15 years where he has designed renovations and new developments of various building types.