Adding a Bedroom To an Apartment

by | Last updated Sep 24, 2021 | Apartment Renovations, Renovations

In NYC you will need a permit to add a bedroom or change the number of rooms in an apartment or house. Bedrooms and habitable spaces have requirements for rooms in regards to size, windows, accessibility, fire protection etc. Adding a bedroom to an apartment involves many code issues, as well as planning and design.

We get lots of inquiries from people who want to add a bedroom to an apartment. This is a relatively common practice. Let’s discuss some of the rules and protocols for adding a bedroom to your apartment. The rules listed below are based on New York City regulations.


Adding A Bedroom / Adding A Room

If you live in an apartment building you will want to make sure your Condo, Co-Op Board, or management company does not have any objections to changing the number of bedrooms in your apartment. For more information on this process, you can read our article on Alteration Agreements.

You will need to hire an architect. The architect will determine the legality of the work. In New York City your architect will file an alteration with the Department Of Buildings (DOB). Typically you will file an “Alt 2” no change to certificate of occupancy. Sometimes the certificate of occupancy lists the number of bedrooms in this case you may be required to file an “Alt 1” to change the certificate of occupancy.

Adding a bedroom to a NY apartment

Bedroom in a Brooklyn Apartment we renovated.

Rules For Bedrooms and Living Rooms

So how do you determine if your new bedroom is going to be legal and can be approved by the DOB. The following are rules as defined by New York City Building Code and Multiple Dwelling Law. Dining rooms, kitchenettes, and bathrooms have different rules we will not address in this article. The codes set rules for habitable rooms which are defined as:

“All rooms and spaces within a dwelling unit in Group R or I-1, including bedrooms, living rooms, studies, recreation rooms, kitchens, dining rooms and other similar spaces”

We have another post that goes deeper on the subject of NYC Code requirements for habitable space. All new rooms and existing rooms must comply with the following.:


Minimum Room Size:

  • Rooms must be a minimum of 80 Square Feet.
    • One room must be at least 150 square feet. (Typically the living room)
    • Do not count closets or wall thickness for floor area of rooms. Room areas are based on net measurements not gross.
  • Rooms must have a minimum height of 8 feet.
  • The room width and depth must have a clear space (not counting furniture of course) of 8 feet as its minimum dimension.
    • For bedrooms in an apartment with 3 or more bedrooms, half the rooms can have a minimum dimension of 7 feet.
      • By half the rooms: we round down so if there are 3 bedrooms then 1 can be 7 feet wide.
      • The bedrooms that are 7 feet wide still need to be 80 square feet minimum.
  • Rooms can not have a space more than 30 feet from a window.
    • There are some exceptions here – we are not going into that level of detail in this article.


Natural Light And Air for legal Rooms:

  • At least one window must be provided in each room.
  • The window must be at least 12 square feet or it does not count for natural light and air.
  • For natural light you need your total window sizes of at least 10% of the room floor area.
    • Example if you have a 240 square foot room you need 24 square feet of window. You can have (2) 12 square foot windows.
    • If your room is less than 120 square feet you still need a 12 square foot window.
    • For a dining room the rule is 1/8 the floor area.
  • For Natural Air you need half the required light so 5% of the room floor area. Meaning when the windows are all open the open area is 5% of the room floor area.
  • Windows on a shared property line do not count, unless you have a legal agreement with your neighbor approved by the DOB, such as a zoning lot merger.
  • Windows must have at least 6 feet clear in front of them.
  • The top of at least one window must be at least 7 feet off the floor.


General Room requirements:

  • If your building is required to be Handicap accessible then the new rooms must all be ADA compliant.
  • You will need to get a permit.
  • In NYC you typically file an Alteration Type 2 with the Department of Buildings for adding bedrooms in an apartment. In some instances you may be required to file an Alteration Type 1
    • Alteration Type 2 is typical. This is when the existing certificate of occupancy does not list the number of rooms (DOB may not require an Alt 1). Also file an Alt 2 if there is no certificate of occupancy on record.
    • Alteration Type 1 is only filed if the Certificate Of Occupancy lists the room count. This is less common. In actuality this may not even be required I have dealt with people at the Department Of Buildings who have instructed us to do it both ways. Your architect will advise you on this. They can meet with the NYC DOB chief plan examiner or borough commissioner.
  • Dining rooms, bathrooms, kitchenettes (under 80 square feet) have different rules.
  • There is no building code or housing code that requires closets in a bedroom, but it sure is a good idea to have one.
  • You must get approval from your Co-Op, condo, or management company before filling with DOB.
  • Skylights only count for light and air in 1 and 2 family houses, not acceptable in a multi family buildings.
Adding a room to a Chelsea loft for a study

Adding a room to a Chelsea loft for a study


Adding a Bedroom to Your Apartment

Adding a Room and Apartment Conversions examples:

Tribeca Loft Bedroom

Tribeca Loft Bedroom


One Bedroom to a Two Bedroom Conversion:

This apartment conversion was in Manhattan on the east side. In this project the client wanted to divide his relatively large living room into a second bedroom and living room. We added the second bedroom see 3D floor plan for before and after. The converted plan maintained a large living area by only adding a small bedroom of a little over 100 square feet. This is a good example of adding a room with minimal impact on the surrounding space. Converting a one bedroom to a two bedroom:

1 bedroom apartment NYC conversion

Original 1 bedroom apartment

Adding a bedroom

1 bedroom converted to 2 bedroom


2 Bedroom to 3 Bedroom Conversion:

This apartment was in a prewar building in Manhattan where we made a 2 bedroom apartment into a three bedroom. The original layout had 2 bedrooms and a large foyer. We relocated the kitchen to the foyer area and converted the living dining room to a bedroom. As well as the original kitchen.

Prewar 2 Bedroom apt NYC

Original 2 Bedroom Apt

prewar apartment renovation

2 bedroom apartment into a 3 bedroom apartment


Studio Apartment To 1 Bedroom Conversion:

This NYC studio apartment was in Chelsea. In this apartment the clients had an alcove bedroom open to the living area. We built a new partition wall with double pocket doors to allow privacy and a separate bedroom, with the option to leave the pocket doors open to create a more open feel. Adding a room to this apartment gave the owners a real sense of privacy and separation that studio apartments don’t have.

Convert studio to 1 bedroom

studio apartment NYC

Original Studio Apartment

Adding a room to a studio apartment

Studio to one bedroom conversion


Making A 2 Bedroom Apartment Into A 3 Bedroom

2 Bedroom Converted into a 3 Bedroom

This apartment is in the Flatiron District. We added a room next to the existing bedroom taking a away from the living room. The apartment still had space for a living room, dining and open kitchen. This is an example of how to make a 2 bedroom apartment into a 3 bedroom.

Loft Renovation NYC

Original 2 bedroom apartment

Adding a bedroom to an apt NYC

Converted 2 Bedroom apartment into a 3 bedroom


Divide a Room into Two Bedrooms

If you want to know how to divide a large bedroom into two rooms I want to caution you about I major point. You cannot have a room that is accessed through a room. This is called a railroad apartment these are illegal in NY. If you divide a room onto two bedrooms they must each have their own entrance from a hallway or open living space.

Below is one of our projects where we divided one bedroom into two bedrooms and added a door for the second bedroom from the open living room.

Divide a room into two bedrooms

Adding a Room in NYC

As an architect I study NYC DOB rules and regulations, but these are complicated and quite involved issues. In this article we reviewed some of the basic concepts with regards to Adding a room in NYC. 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 Height Factor Zoning.

I hope this article was helpful for you. If you would like to speak with an architect about a project you are planning feel free to contact us directly.


Contact Fontan Architecture


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 15 years where he has designed renovations and new developments of various building types.