R3-1 Zoning NYC

by | Last updated Jul 3, 2020 | NYC Zoning

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


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.

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.


R3-1 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 R3-1 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 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 with an architect you can contact us directly.


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Jorge Fontan

Jorge Fontan

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.