R3-1 Zoning NYC
R3-1 Zoning is a low density residential zoning contextual district in NYC. You can build single family or 2 family homes that are either detached or semi detached in R3-1.
The R3-1 Zoning District is a contextual sub district of R3 Zoning in NYC. R3-1 Zoning is mapped in The Bronx, Brooklyn, Queens, and Staten Island.
R3 Zoning Districts
R3 Contextual Districts
R3-1 Zoning Regulations
The New York City Zoning Resolution is complicated and quite in depth. In this article we will review some basic Zoning Codes with regards to residential zoning district R3-1. This analysis does not assume to cover every possible issue, but provide a general overview of the zoning codes.
R3-1 Zoning Community Facility
R3-1 Zoning is a residential zone but Community Facility uses are allowed in R3 zones. In the instance of a community facility the zoning calculations may be different as community facilities can have different requirements.
R3-1 Zoning Specifications
Minimum Lot Size: Lot Area & Lot Width
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:
Semi detached houses are built in pairs they touch in the middle but have yards on the sides.
Minimum Lot width =18 Feet
Minimum Lot Area = 1,700 Sq Ft
Lot Coverage & Open Space
Maximum Lot Coverage: 35%
The development can not cover more then 35% of the property.
Required Open Space: 65%
The development must leave 65% of the property with open space.
R3-1 Floor Area Ratio (FAR):
Floor Area Ratio determines the floor area that can be built on the property. The floor area ratio is multiplied by the lot area.
FAR = .5
Attic Allowance 20% bonus
In R3-1 Zoning districts the FAR may be increased by 20% for floor area located under a pitched roof. This is not always possible to achieve.
Density Factor or Dwelling Unit Factor (DU) for R3-1
The Dwelling Unit factor determines the maximum number of dwellings or families on the property.
625 – 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 if you can build 2 families or only one.
R3-1 Building Heights:
Perimeter Wall Height = 21 Feet
Building Height = 35 Feet
Yard Requirements for R3-1
Front Yard = 15 Feet minimum
Rear Yard = 30 Feet
Side Yards Detached = 13 Feet in total with the smaller being 5 feet each
Side Yards Semi Detached = 8 Feet
R3-1 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.
R3-1 Example Lot
Lets assume we have a 50 foot wide and 100 foot deep property in an R3-1 Zoning District in Brooklyn on an interior lot.
Optional Lot Subdivision
In this example we could potentially divide the lot into two separate lots and build two semi detached houses. We will do the zoning example as if we are dividing the lots.
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 50 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 25 feet wide and 2,500 square feet each. The 2,500 square foot lots 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 .5. 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 .5
Lot Size of 25 feet x 100 feet.
Zoning Floor Area = Lot Area X FAR
Lot Area = 25 x 100
Lot Area = 2,500 sq ft
FAR = .5
Zoning Floor Area = 2,500 sq ft x .5
Zoning Floor Area = 1,250 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. We will assume that we can maximize the attic allowance for this example.
Zoning Floor Area with Bonus 1,500 sq ft
So we can build a 1,500 sq ft for each house.
How may families can we have on our R3-1 lot.
Zoning regulates the maximum number of residential units you can put in a building. In these houses we have 1,500 square feet each. We then take the zoning Area and divide by the Density factor.
Number Of Families = Zoning Floor Area ÷ Density Factor
Number Of Families = 1,500 ÷ 625
Number Of Families = 2
Maximum Number Of families = We can build 2 two family houses resulting in a total of 4 families.
R3-1 Zoning Example Conclusion
In this example we are proposing to develop 2 semi detached houses with a total of 4 residential units. The buildings would be semidetached. We will need to provide parking for every family.
Thank You for reading our post on R3-1 Zoning in NYC.
I hope this was helpful. You can leave questions or comments below. If you want to discuss a specific project or want help with zoning review please feel free to contact Fontan Architecture directly. We will be happy to help.
Author Jorge Fontan AIA
This post was written by Jorge Fontan, a Registered Architect and owner of Fontan Architecture.