R4B Zoning NYC

(Last Updated On: December 17, 2018)

R4B Zoning is a low density, contextual residential zoning district in NYC that allows for one family and two family homes. The houses can be built as detached, semi detached, attached, and zero lot line residences.

 

R4B ZONING 

R4B is a sub district or R4 zoning. Two major differences between R4 and R4B is that R4B does not allow multi family (3 families or more is multifamily). Is mapped in Brooklyn or Queens.

R4 Zoning Districts

R4 Contextual Districts

 

R4B 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 R4B. This analysis does not assume to cover every possible issue, but provide a general overview of the zoning codes.

 

R4B Zoning Community Facility

R4B Zoning is a residential zone but Community Facility uses are allowed in R4 zones. In the instance of a community facility the zoning calculations may be different as community facilities can have alternate requirements.

 

R4B Zoning Specifications

Lot Size 

You can only build one or two family homes in R4B. The buildings can be Detached, semi detached, zero lot line, or attached.

Lot Size For Detached or Zero Lot Line

Minimum Lot width =25 Feet

Minimum Lot Area = 2,375 Sq Ft

Lot Size For attached or semi-detached

Minimum Lot width =18 Feet

Minimum Lot Area = 1,700 Sq Ft

Floor Area Ratio (FAR):

Floor Area Ratio determines the floor area that can be built on the property.

FAR = .9

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 if you can build 2 families or only one.

Building Heights: 

Building Height = 24 Feet

Yards:

Front Yard = 5 Feet

Rear Yard = 30 Feet

Zero Lot Line Side Yards = 8 Feet

Detached = 2 side yards combined adding up to 8 feet

Semi detached = 4 feet

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.

 

R4B 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-B ZONING EXAMPLE LOT

Lets assume we have a 30 foot wide and 100 foot deep property in an R4B Zoning District in queens 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.

Zoning Floor Area/ Floor Area Ratio (FAR)

So the floor area ratio is .9. 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 .9

The lot Size is 30 feet x 100 feet.

Zoning Floor Area = Lot Area X FAR

Lot Area = 30 x 100

Lot Area = 3,000 sq ft

FAR = .9 or

Zoning Floor Area = 3,000 sq ft x .9

Zoning Floor Area 2,700 sq ft

So we can build a 2,700 sq ft for the house.

HOW MANY FAMILIES CAN WE HAVE ON OUR R4B LOT?

Zoning regulates the maximum number of residential units you can put in a building. We take the zoning Area and divide by the Density factor.

Number Of Families = Zoning Floor Area ÷ Density Factor

Number Of Families = 2,700 ÷ 870

Number Of Families = 3 but we can only build 2 because 3 families is not allowed.

Maximum Number Of families = We can build a 2 two family house.

R4B ZONING EXAMPLE CONCLUSION

We can build a 2 family house of 2,700 square feet counting the attic. We will need to provide parking for every family.

 

THANK YOU FOR READING OUR BLOG POST ON R4B ZONING.

I hope this was helpful. You can leave questions or comments below. If you want to discuss a specific project with an architect please feel free to contact Fontan Architecture directly. We will be happy to help.

 

New York Architects, Jorge Fontan

Author Jorge Fontan AIA

This post was written by Jorge Fontan, a Registered Architect and owner of Fontan Architecture.

7 Comments

  • Freddie Escobeo

    August 21, 2018 7:05 pm
    Reply

    Great post.

  • Patrick DeBernardi

    January 5, 2019 10:26 pm
    Reply

    Hello Jorge,
    I’m a Realtor in Queens, NY and I have a listing in Flushing. The property is in a R4B zone. The lot size is 28 X 100 , semi detacted Corner home One Family with a building size of 20.33 X 36 ft. . Would like to know if this property can be converted to a Two Family base on the facts and formula stated in your post, keeping in mind it is a Corner property. I don’t want to misinform my potential buyers that this is possible.
    Would greatly appreciate any information you could give me in regards to this property and the maximum FAR and Building size that can be built on this Lot.
    Thank You
    Patrick DeBernardi of Carollo Real Estate

  • Carol Stephens

    February 6, 2019 8:37 pm
    Reply

    Wonderful post – Based on the excellent explanation that you have provided, is the following math correct for converting a 1 family to a 2 -family. It’s a 1 family in Queens- R4B zone; Lot size – 2,000 sq.ft.; FAR .9 ; so the maximum zoning floor area is 1,800 sq.ft. Dividing 1,800 sq.ft by 870 equals 2.068 – 2 units?? The listing states that the property has 2 garage spaces.

    I realize that a complete zoning analysis must be done to provide an informed answer, but I would just like to know if I did the math correctly to determine if I should pursue the property further and get a zoning analysis.

    Thank you.

  • Marielle

    March 20, 2019 12:35 pm
    Reply

    Hi Jorge,

    Wonderful website. I live in a R4b home. The neighbor (who owns building for investment) is converting their R4b from one to two family home. They have have done an 12 foot extension to the dwelling and now adding an 8 foot deck to both levels. Beyond the fenced in yard is a parking space and one car garage (which is attached to our garage and then we have one spot on our side).

    Can they build such a large deck? Doesn’t this violate the required 30 feet of back yard they must have? Does the back yard footage start after the deck? Can they count their parking space and garage dwelling to the property line as yard area?

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