R4-1 Zoning NYC(Last Updated On: January 14, 2019)
R4-1 Zoning is a residential zoning district in NYC that allows for one family and two family residences only. You can build detached, semi detached, and zero lot line buildings. R4-1 zones often have small homes built individually or in pairs.
R4-1 is a sub district or R4 zoning. Two major differences between R4 and R4-1 is that R4-1 does not allow multi family (3 families or more) and does not allow attached buildings. You can build two houses touching each other, this is called semi detached. You cannot build in groups of more then 2 houses.
R4 Zoning Districts
R4 Contextual Districts
WHAT IS R4-1 ZONING?
R4-1 Zoning is considered “low density” residential zoning. It typically has 2 or 3 story homes of 1 or 2 families each. When there is a 3rd story it will be within a pitched roof. The pitched roof is very common in R4-1 Zoning because of its zoning requirements and floor area bonus for attic space.
R4-1 ZONING COMMUNITY FACILITY
R4-1 Zoning is a residential zone but Community Facility uses are allowed in R4-1 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.
R4-1 ZONING REGULATIONS
Lot Size Detached & Zero Lot Line:
A Detached house has yards on all sides. A zero lot line is built on a property line on one side but does not abut another house.
Minimum Lot width =25 Feet
Minimum Lot Area = 2,375 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
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 if you can build 2 families or only one.
Perimeter Wall Height = 25 Feet
Building Height = 35 Feet
Front Yard = 10 Feet if greater then 10 it must be at least 18 Feet
Rear Yard = 30 Feet
Side Yards Detached = 8 Feet in total 4 feet each
Side Yards Zero Lot Line = 8 feet One Yard Required
Side Yards Semi Detached = 4 Feet (There are special instances where this can be greater then 4 feet in R4-1 Zoning)
1 Parking Space must be provided for each dwelling unit.
R4-1 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.
R4-1 ZONING EXAMPLE LOT
Lets assume we have a 40 foot wide and 100 foot deep property in an R4-1 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.
R4-1 ZONING EXAMPLE LOT 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 25 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
Each new lot Size is 20 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 R4-1 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.
R4-1 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.
THANK YOU FOR READING OUR BLOG POST ON R4-1 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.
Author Jorge Fontan AIA
This post was written by Jorge Fontan, a Registered Architect and owner of Fontan Architecture.