R4 Zoning NYC Multi family building

R4 Zoning NYC

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 

This post will focus on regular R4 but, there are different types of R4 Zoning including subdistricts:

  • R4
  • R4 Infill
  • R4-1
  • R4A
  • R4B

 

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 ihow 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

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. In these houses we have 1,800 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 = 1,800 ÷ 870

Number Of Families = 2

Maximum Number Of families = We can build 2 two family houses resulting in a total of 4 families.

 

R4 Zoning NYC Attached Semi Detached

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. In this building development we have 3,600 square feet. We then take the zoning Area and divide by the Density factor.

Number Of Families = Zoning Floor Area ÷ Density Factor

Number Of Families = 3,600 ÷ 870

Number Of Families = 4

Maximum Number Of families = We can build a four family building.

 

R4 Zoning Multi family 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.

 

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 please feel free to contact Fontan Architecture directly. We will be happy to help.

 

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

No Comments

Post a Comment