R4 Zoning is a residential zoning district in NYC that allows for one family and two family as well as small multifamily residential building. You can build detached, semi detached, and attached buildings in R4 Zoning.
R4 Zoning Districts
This post will focus on regular R4 but, there are different types of R4 Zoning including subdistricts:
WHAT IS R4 ZONING?
R4 Zoning is considered “low density” residential zoning. It typically has 2 or 3 story homes of 1 or 2 families each or small multi family buildings. When there is a 3rd story it will be within a pitched roof. The pitched roof is very common in R4 Zoning because of its zoning requirements and floor area bonus for attic space. R4 zoning most commonly has attached homes.
R4 Infill Housing
Predominantly Built Up Area R4
If a property is locate don a block that is completely within an R4 zoning district it may qualify for R4 Infill Housing also known as Predominantly Built Up Area. Properties qualifying as R4 “Infill Housing” have a separate set of zoning specifications where you can develop a slightly larger building.
R4 ZONING COMMUNITY FACILITY
R4 Zoning is a residential zone but Community Facility uses are allowed in R4 zones. In the instance of a community facility the zoning calculations would be different. One can potentially build a mixed use building with both community facility and residential use.
Multi Family Buildings In R4
A Multi family building is any building with 3 or more residential units. Multi Family is not as common in R4 as one and two family homes, nonetheless you can develop either. We have an R4 case study of a development involving both 2 family homes and a multi family building in The Bronx.
R4 ZONING REGULATIONS
Lot Size Detached:
A Detached house has yards on all sides and does not touch any other buildings or houses.
Minimum Lot width =40 Feet
Minimum Lot Area = 3,800 Sq Ft
Lot Size for Semi-Detached or attached:
Semi detached houses are built in pairs they touch in the middle but have yards on the sides. Attached houses are built to the property lines.
Minimum Lot width =18 Feet
Minimum Lot Area = 1,700 Sq Ft
Lot Coverage:
The development can cover a maximum of 45% of the property.
Floor Area Ratio (FAR):
Floor Area Ratio determines the floor area that can be built on the property.
FAR = .75
FAR attic allowance = 20% bonus (.9 FAR total)
Density Factor or Dwelling Unit Factor (DU)
The Dwelling Unit factor determines the maximum number of dwellings or families on the property.
870 – This is used to calculate how many units you can have. The total residential floor area is divided by this factor to get the maximum allowable number of dwelling units. This calculation will let you know how many families you ca develop here.
Building Heights:
Perimeter Wall Height = 25 Feet
Building Height = 35 Feet
Yards:
Front Yard = 10 Feet minimum but, if greater then 10 it must be at least 18 Feet
Rear Yard = 30 Feet
Side Yards Detached = 13 Feet in total with the smaller being 5 feet each
Side Yards Semi Detached = 8 Feet
Side Yards for Multifamily = Must Have two side yards of 8 feet each
Side yards can be waived for the abutting side(s) of attached buildings. There are requirements for this that must be met to qualify.
Parking:
1 Parking Space must be provided for each dwelling unit.
R4 ZONING EXAMPLE
Here is an example zoning analysis. Be aware that zoning is complicated and I am only addressing the basics here. I assure you there are many additional issues and variations to consider beyond this example.
R4 ZONING EXAMPLE LOT
Lets assume we have a 40 foot wide and 100 foot deep property in an R4 Zoning District in Brooklyn on an interior lot. If we are looking to build the most units we can, we would want to divide the lot into 2 different lots or develop a multi family building.
R4 ZONING EXAMPLE LOT SUBDIVISION CALCULATIONS:
Lot Area and Width
If we want to do a lot subdivision we will need to examine the lot size. The minimum lot width for a detached home is 40 feet. We started with a 40 foot lot so we cannot divide this into 2 detached lots. The minimum size for a semi detached would be 18 feet. In this case we are good. We can make 2 lots 20 feet wide and 2,000 square feet. The 2,000 square feet exceed the minimum lot area of 1,700 square feet. The zoning calculations below will be for 1 of the properties.
Zoning Floor Area/ Floor Area Ratio (FAR)
So the floor area ratio is .75. The FAR is a ratio that determines how many square feet you can build on the property. You simply take the property size and multiply it by the FAR.
In this example we have:
FAR of .75
Lot Size of 40 feet x 100 feet.
Zoning Floor Area = Lot Area X FAR
Lot Area = 20 x 100
Lot Area = 2,000 sq ft
FAR = .75 or
Zoning Floor Area = 4,000 sq ft x .75
Zoning Floor Area = 1,500 sq ft
There is a zoning Bonus for Attic allowance of up to 20%. Attic allowance is a little complicated, you will not always be able to maximize the attic allowance. In this case we can maximize it because this is based on a real project of ours.
Zoning Floor Area with Bonus 1,800 sq ft
So we can build a 1,800 sq ft for each house.
HOW MANY FAMILIES CAN WE HAVE ON OUR R4 LOT?
Zoning regulates the maximum number of residential units you can put in a building.
R4 Zoning NYC two Semi Detached 2 family houses
R4 ZONING EXAMPLE CONCLUSION
In this example we are proposing to subdivide the lot into 2 lots of 2,000 square feet each. We will be building one semi detached house on each lot. The two houses will be abutting in the middle with side yards on the outsides. We can have 2 families in each house for a total of 4 families. We will need to provide parking for every family.
R4 Zoning Multi Family Building Example:
Lot Area and Width
If we are going to build a multifamily building in R4 we would not want to subdivide the lot. We would build a detached building. In this example we have a 40 foot wide lot and a 4,000 square foot lot. The lot width is exactly the minimum for a detached structure so we are good there and the lot area exceeds the minimum of 3,800 sq feet making this okay on both.
Zoning Floor Area/ Floor Area Ratio (FAR)
So the floor area ratio is .75. The FAR is a ratio that determines how many square feet you can build on the property. You simply take the property size and multiply it by the FAR.
In this example we have:
FAR of .75
Lot Size of 40 feet x 100 feet.
Zoning Floor Area = Lot Area X FAR
Lot Area = 40 x 100
Lot Area = 4,000 sq ft
FAR = .75
Zoning Floor Area = 4,000 sq ft x .75
Zoning Floor Area = 3,000 sq ft
There is a zoning Bonus for Attic allowance of up to 20%. Attic allowance is a little complicated, you will not always be able to maximize the attic allowance.
Zoning Floor Area with Attic Allowance Bonus 3,600 sq ft
So we can build a 3,600 sq ft for the building.
HOW MANY FAMILIES CAN WE HAVE ON OUR R4 LOT?
Zoning regulates the maximum number of residential units you can put in a building.
R4 Zoning Multi family building Diagram 4 units
R4 ZONING EXAMPLE CONCLUSION
In this example we are proposing to develop one multi family building with 4 residential units. The building would be detached with yards on all 4 sides. We will need to provide parking for every family.
R4 Zoning in NYC
As an architect I study Zoning Codes closely, but these are complicated and quite involved issues. In this article we reviewed some of the basic concepts with regards to the R4 Zoning Districts. This post does not assume to cover every possible issue or condition, but provide a general overview of the topic.
THANK YOU FOR READING OUR BLOG POST ON R4 ZONING.
I hope this was helpful. You can leave questions or comments below. If you want to discuss a specific project with an architect you can contact us directly.
Contact Fontan Architecture
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 20 years where he has designed renovations and new developments of various building types.
