Sunday, September 30, 2007

When do the new NYC Construction Codes go into effect?

Q: When do the new NYC Construction Codes go into effect?

A: The new NYC Construction Codes are scheduled to go into effect on July 1, 2008. A draft of the Code is available for download at the NYC Department of Buildings Website.

I have attempted to paraphrase below (from Local Law 33 of 2007) the enactment transition details. Please refer to Local Law 33 of 2007 for the exact enactment language.

Any application submitted to the DOB prior to July 1, 2008, or for which an application is submitted to the DOB within a period of 12 months after July 1, 2008, at the option of the owner, may be performed in its entirety in accordance with new NYC Construction Codes, or in accordance with the 1968 building code, provided that the construction work is commenced within 12 months after the date permit issuance and is diligently carried on to completion.

The Commissioner may, for good cause, extend the time period for commencement of the work beyond 12 months. Where the owner elects to perform the work in compliance with the 1968 building code, certain conditions shall apply. Please refer to the Local Law for the conditions.

Optional use of the 1968 Building Code for alteration of existing buildings. At the option of the owner, a permit may be issued after July 1, 2008 authorizing work on existing buildings to be performed in accordance with the 1968 building code, subject to certain conditions. Please refer to the Local Law for the conditions.

Thursday, September 27, 2007

Non-Profit Institution with Sleeping Accommodations

Q: What is the proper way to indicate a Non Profit Institution with Sleeping Accommodations on a Schedule-A or Certificate of Occupancy?

A: For a New Building, which is a Non-Profit Institution with Sleeping Accommodations:

Description: Non-Profit Institution with Sleeping Accommodations
Occupancy Group: J-2-Residential
Use Group: 3-Community Facility
Multiple Dwelling Classification: HAEA
List Number of Dwelling Units Per Floor? Yes

Wednesday, September 26, 2007

Stair Landings?

Q: What is the minimum required size of a Stair Landing for an Egress/Exit Stair? Where are Stair Landings required? What is the maximum vertical rise of a Stair before Intermediate Landings are required?

A: Below are some paraphrased Code Sections answering these questions:

1. Stair Landings and Platforms shall be provided at the head and foot of each flight of stairs, except at the head of a basement stair in one- and two-family dwellings.

2. The minimum width of stair landings and platforms perpendicular to the direction of egress shall be equal to at least the width of the stair.

3. Intermediate landings need not be more than 44" wide.

4. The maximum vertical rise of a single flight of stairs shall not exceed:

  • 8' in Occupancy Group F (Place of Assembly) and H (Hospital, Nursing Home, Mental Institution, Jail)

  • 12' in all other Occupancy Groups.

Provide an Intermediate Landing where the vertical rise exceeds these distances.

4. The swing of stair doors shall not block stairs or stair landings.

5. The swing of a Stair Door shall not reduce the clear width of the Stair landing to be less than seventy-five percent of the required width of the landing or stair.

6. The swing of a Stair Door shall not reduce the clear width of the Stair landing to be less than the width of the door opening on them.

See BC Section 27-375(d) and 27-375(g) for the exact wording/additional details

Monday, September 24, 2007

Tent Requirements?

Q: What are the Building Code requirements for Tents?

A: Tents and Air Supported Structures are covered in BC Subchapter 7 Special Uses and Occupancies, Article 19. See this Code Section for the full requirements, some of which are summarized below:

1. Tents and Air Supported Structures shall not exceed One (1) Story in height above the ground or roof they are erected on.
2. Tents shall be at least 20 feet from all Interior Lot Lines.
3. Tents shall be at least 30 feet from any unportected opening, required exterior stairway or corridor, or required exit door in an adjacent building.
4. A Tent may abut another building if there are no unprotected openings in the abutting building's wall, and if the wall of such building is a Fire Division with the required Fire Rating.
5. In addition to the minimum exterior separation distances listed above, Tents shall comply with the Yard Requirements of the applicable Zoning District.
6. The ground enclosed by the Tent and 10' around the Tent shall be cleared and maintained free of all combustible material and vegetation.
7. No Open Flame is permitted within 20' of the Tent enclosure fabric.8. Travel Distance within the tent shall not exceed 75'. Exit doors shall be located in frames so they will remain operational even if the Tent or Air Supported Structure collapses.
9. Tents shall be guyed, supported, and braced to withstand a wind pressure of 10 pounds per square foot of projected area of the tent. The poles and their supporting guys, stays, stakes, fastenings, etc shall resist wind pressure of 20 pounds per square foot of projected area of the Tent.
10. All materials used for Tents shall be treated to be flameproofed.
11. Certificates of Occupacy for Tents shall be issued for a period not exceeding one year, such certificates may be renewed if the Tent continues to comply with all requiredments.

Sunday, September 23, 2007

Class A Multiple Dwelling or Class B?

Q: What is the difference between a Class A Multiple Dwelling and a Class B Multiple Dwelling?

A: A Class 'A' Multiple Dwelling is for permanent residential occupancy. A Class 'B' Multiple Dwelling is for transient residential occupancy. See MDL Sec 4 (Definitions), Items 8 & 9:

"8. A "Class A" multiple dwelling is a multiple dwelling which is occupied, as a rule, for permanent residence purposes. This class shall include tenements, flat houses, maisonette apartments, apartment houses, apartment hotels, bachelor apartments, studio apartments, duplex apartments, kitchenette apartments, garden-type maisonette dwelling projects, and all other multiple dwellings except class B multiple dwellings.

9. A "Class B" multiple dwelling is a multiple dwelling which is occupied, as a rule transiently, as the more or less temporary abode of individuals or families who are lodged with or without meals. This class shall include hotels, lodging houses, rooming houses, boarding houses, boarding schools, furnished room houses, lodgings, club houses, college and school dormitories and dwellings designed as private dwellings but occupied by one or two families with five or more transient boarders, roomers or lodgers in one household."

Lot Line Windows?

Q: What is a Lot Line Window? Where can I find the DOB guidelines governing Lot Line Windows?

A: Lot Line Windows are windows installed in an Interior Lot Line Wall, meaning in the walls of the building which run along & directly adacent to the side property lines. Walls along the side property line need to be fire rated in accordance with Table 3-4. Windows may, under certain conditions, be installed in Lot Line Walls, with the following restrictions:

1. Lot Line windows are of very limited area (see Table 3-4 & TPPN 10/87)
2. Lot Line Windows cannot serve as required windows for light & ventilation (amenity only).
3. Lot Line Windows must be constructed of wired, tempered, or laminated glass, and must be protected with a Sprinkler Head mounted on the inside of the occupied space.
4. Lot Line Windows must be sealed if an adjacent property owner enlarges their building vertically to block such openings.
5. A Lot Line Window Declaration is required between adjacent property owners.

Asbestos Investigation for New Building?

Q: How recently constructed does a New Building need to be to avoid an Asbestos Investigation requirement?

A: Buildings filed with the DOB after April 1, 1987 do not require an Asbestos Investigation (ACP-5). In lieu of the ACP-5, an ASB-4 'Asbestos Exemption Form' must be filed. This form must be signed & sealed by the Architect or Engineer of Record.

Wednesday, September 19, 2007

Pool Permits?

Q: Where can I find the Department of Health Permit Requirements and Applications for an Indoor or Outdoor Pool, Jacuzzi, with or without a Sauna and/or Steam Room?

A: Pool Permits are reviewed by the NYC Department of Health-Office of Public Health Engineering, 2 Lafayette Street, 11th Floor, New York, NY 10007, tel:212-676-1520, Fax 212-676-1517.

Under the NYS Sanitary Code, Chapter 1, Subpart 6-1, and Article 165 of NYC Health Code, no Municipality, School District, Person, Group of Pertons, Firm, Corporation, Association, Organization or Institution shall install or construct a Bathing Establishment in the City of New York without an appropriate permit issued by the New York City Department of Health.

Pool Waste Water must be disposed of through the New York City sewer system. Permission/Approval for subsurface connection and disposal system must be obtained from the NYC Department of Environmental Protection (DEP). Once permission is granted, a copy of Permission Letter to the Applicant will be forwarded by NYC DEP to the Bureau of Public Health Engineering.

For information on the NYC DEP Application Requirements, please contact:

Herbert Kass, P.E., Chief
New York City Department of Environmental Protection
Bureau of Water Supply and Wastewater Collection
59-17 Junction BoulevardCorona, NY 11368
Tel: 718-595-5330

If underwater lights are to be installed in the Pool, an approval letter from the New York City Department of Buildings is required. For information contact:
Edward Solomon, P.E.Chairman, Advisory Board
New York City Department of Buildings
1 Centre Street, Room 1415
New York, NY 10007 Tel: 212-669-8673

A Certificate of Occupancy from New York City Department of Buildings showing the specific usage on the corresponding floor is required (A Temporary Certificate of Occupancy is also acceptable).

The Permit Approval Process is comprised of three parts:
-Part I, Plan Review and Approval
-Part II, Construction Inspection
-Part III, Permit Review and Issuance

An approval of the permit will be granted when the pool is designed, constructed, and completed in accordance with:

-Article 165, New York City Health Code
-Other requirements which the Bureau of Public Health Engineering may determine are necessary to adequately review and approve the permit

The Permit Application Fee is $1,980 in a check made payable to the New York City Department of Health.

What is the definition of a Cabaret?

Q: What is the definition of a Cabaret? What are the Code Requirements for a Cabaret?

A: Cabaret is defined by the NYC Building Code as any room, place or space in which any musical entertainment, singing, dancing or other similar amusement is permitted in connection with an eating and drinking establishment.

Cabarets are classified as F-4 Place of Assembly Occupancy Group.
The Zoning Use Group depends upon the Occupant Load and whether there is dancing or not:

Use Group 6:

  • Eating or Drinking Establishments with Entertainment or Musical Entertainment, but not dancing, with a capacity of 200 persons or less.

Use Group 12:

  • Eating or Drinking Establishments with Entertainment and a capacity of more than 200 Persons, or establishments of any capacity with Dancing

Some Code Requirements for Cabarets:

-Cabarets shall be equipped with Emergency Lighting per §27-542 (retroactive requirement)

-Cabarets shall be fully sprinklered per §27-954(s)(1).

-Cabarets shall have Fire Alarm Systems per §27-968(a)(10)(b).

-Cabaret Stages, Dressing Rooms, and Property Rooms shall be provided with Automatic Sprinkler and Fire Alarm protection per §27-954(s)(2), 27-549(a)(3), and §27-968(a)(10)(a).

Stages in Cabarets with Scenery or Scenic Elements shall comply with Stage Requirements for an F1-A Places of Assembly (Sprinkler Deluge required)

Stages in Cabarets without Scenery or Scenic Elements shall comply with those in F1-B Places of Assembly (§27-547):

-Raised platforms may be built as stages in F-1b places of assembly when they are supported on floors having the fire resistance ratings required by Table 3-4, in accordance with the following:

-The area below the platform shall be enclosed on all sides with solid construction.

-The horizontal area of stage construction shall not exceed the following:

Wood frame: maximum area - 400 square feet.
Fire retardant treated wood: maximum area - 1,200 square feet.
Noncombustible frame: maximum area - unlimited.

-The floor of the stage, when wood is used, shall be at least one inch nominal thickness, and shall be laid on a solid, noncombustible backing, or all spaces between supporting members shall be fire-stopped with noncombustible material.

Tuesday, September 18, 2007

I have received an ECB Violation. What is the ECB?

Q: I have received an ECB Violation. What is the ECB?

A: ECB stands for 'Environmental Control Board'. ECB Violations are commonly issued by the NYC Department of Buildings and NYC Fire Department for violations of the Building Code or Building Laws.

An example of a common FDNY-issued ECB Violation might be: "Failure to provide Equipment Use Permits for Rooftop Condenser HVAC Units"

Below is a description of the Environmental Control Board from the ECB's Website:
"The Environmental Control Board (ECB) is an administrative tribunal, which means that it is a decision-making body that hears disputes like a court, but with a few important differences. ECB only hears cases in which people are charged with violating New York City's quality-of-life laws - the laws that protect the health, safety, and cleanliness of our environment and neighborhoods. Quality-of-life violations are not criminal offenses. For this reason, ECB issues only monetary penalties and/or orders to correct violations when it finds people in violation of the City's quality-of-life laws.

ECB is like a court in many ways. Like a court, ECB conducts hearings to resolve quality-of-life violations. At these hearings, parties can present evidence in order to prove or disprove alleged violations. Cases are heard by lawyers with specialized training called Administrative Law Judges (ALJs), who act as impartial decision-makers. However, ECB is less formal than a court. Legal counsel is not required, and most people choose to represent themselves. Cases are not presented in a courtroom and the ALJs do not wear robes."

Friday, September 14, 2007

Spiral Stairs?

Q: Are Spiral Stairs permitted as an interconnecting stair in Vertical Duplex Apartments?

A: Per BC Section 27-375(l). Spiral stairs may be used as an interconnecting stair in a Duplex Apartment. They should have at least 30" long treads. Per the below, spiral stairs do not count towards required exits. However, if the connected floor were a mezzanine and the stair was non-combustible, you might get it accepted as a means of egress under a Recon. You need to comply with the Duplex Apt Memo as well.

BC Section:
Spiral stairs may serve as access stairs between two floors or levels in accordance with the provisions of paragraph two of subdivision (i) of this section.

Such stairs may not serve as required exits, except that unenclosed spiral stairs when built of noncombustible materials and having a tread length of at least thirty inches may serve as exits from mezzanines or balconies having an occupant load not exceeding twenty-five persons.

Local Laws

Q: Where can I obtain a copy of a Local Law that DOB has referenced, but that is not available at the DOB or online at the DOB's Web Site?

A: Copies of Local Laws may be requested at the Municipal Reference Library located at 31 Chambers Street, New York, NY

MEA Number for Wheelchair Lifts?

Q: Is an MEA Number required for a Wheelchair or Handicap Lift?

A: An MEA Number is not required for a Wheelchair Lift. Any wheelchair Lift specified to provide access for persons in Wheelchairs must be approved by the DOB Elevator Division. However, an MEA Number is not required. This policy applies to vertical and inclined wheelchair lifts.

Marquees and Canopies

An example of a Canopy, with posts that support the end of the Canopy on the Sidewalk

An example of a Marquee, supported entirely from the Building. This is a small one.

Q: What is the difference between a Marquee and a Canopy?

A: Marquees are fully supported from the building alone. A Canopy has posts that come down onto the sidewalk as additional support. Canopies require DOT Approval. Marquees may be approved by the DOB as a Permissible Projection if they comply.

Door Ratings?

Q: What is the required Fire Resistance Rating for a Door installed in a rated Wall?

A: Refer to Table 5-3 Opening Protectives for Fire Divisions and Fire Separations.Per the Table:

Wall Rating= 3 or 4 hrs = Door Rating of 3 hrs (A Label)
Wall Rating= 2 or 1 1/2 hrs = Door Rating of 1 1/2 hrs (B Label)
Wall Rating= 1 hr = Door Rating of 3/4 hr (C Label)

What is an MEA Number?

Q: What is an MEA#?

A: An MEA Number is the number assigned to a piece of equipment or assembly that has been approved for use in New York City by the MEA Division.

The Materials and Equipment Acceptance (MEA) Division was created in 1969. Prior to 1969, the Board of Standards and Appeals (BSA) was the agency having jurisdiciton. The MEA division regulates "certain materials and equipment (that) require Department of Buildings acceptance. These manufactured items affect public safety, health and welfare (including structural stability and fire safety) and are usually a permanent part of a building. They include such items as boilers, air-conditioning equipment, commercial cooking equipment, fire-rated assemblies, fire alarm and suppression equipment, etc. The actual list of accepted products to date is known as the MEA Index."

If you are installing a new Boiler in your building, for instance, the Engineer's Plans must contain a Boiler Schedule including (amongst other information) the MEA Number of the Boiler. Failure to provide the MEA Number on your plans will cause diapproval of the plans until the MEA Number is provided.

Place of Assembly with Multiple Spaces

Q: I have a Place of Assembly with multiple spaces that are open to one another or are separated by non-fire rated construction. How do I define the limits of my Place of Assembly, and the Total Number of Occupants?

A: When Place of Assembly Spaces are open to one another or are separated by non-fire rated construction, the spaces should be considered all one Place of Assembly. One PA Application should be filed, and the aggregate total of Occupants for all spaces will be the Maximum Number of Persons for the Place of Assembly. A Reconsideration may be required for this condition.

Home Improvement Contractor's License

Q: When is a Home Improvement Contractor's License required by the NYC-Department of Buildings for a DOB Work Permit?

A: Contractors must have a Home Improvement Contractor's License when obtaining a permit for alterations to:

-1, 2, 3 or 4 family homes
-Co-op units, condo units or rented apartment units

Who will this affect?:Any construction contractor Professional Engineers or Registered Architects hiring a contractor (design/build contracts)

A Home Improvement License is not required if you are:
-A Professional Engineer or a Registered Architect who does not have a Design-Build Contract
-A Subcontractor
-A homeowner performing his or her own work
-A Contractor for a new building
-Performing work in a residence that is owned or controlled by a government agency
-Performing work in only the commercial portion of a building
-Performing work in a Multiple Dwelling and hired by the building owner or Board of Directors

Standpipes Required During Construction

Q: When is it necessary to have a Standpipe System during Construction?

A: Standpipes are an imporant part of the Fire Protection systems of buildings, including those that are under construction or demolition. The Standpipe is a vertical riser which provides firemen with a means of water supply for fighting fires within the building, especially in high-rise buildings.

During construction of a New High Rise Building (buildings exceeding 75 feet in height), a Temporary Standpipe is required by the Building Code. A Licensed Fire Suppression Contractor may submit an Alteration Repair Application as an initial filing to start work on a standpipe system as required by Section 27-1014(b) of the NYC Building Code. An approved ARA-1 will serve as a Temporary Permit until the permanent Standpipe Plans are approved by the NYC-Department of Buildings.

Summary of Code Section requiring Temporary Standpipe System:
A Standpipe shall be provided when construction or alteration work reaches 75' in height or more. The standpipe shall be kept in readiness at all times for fire department use. The system shall be a dry system when freezing conditions may be encountered.

In strucures being demolished which have existing Standpipe Systems, such systems shall be maintained as Dry Standpipes. The standpipe risers shall be capped above the outlet on the floor immediately below the floor being demolished so as to maintain the standpipe system on all lower floors for fire department use.

In structures undergoing demolition which have existing sprinkler systems with siamese hose connections, such system shall be maintained as a non-automatic sprinkler system. When demolition starts, the sprinkler risers shall be capped immediately below the floor being demolished so as to maintain the sprinkler system on all lower floors for fire department use.

Work Types?

Q: What is a Work Type? Where can I get a comprehensive list of the Work Types? What is required to signoff each Work Type?

A: The NYC Department of Buildings has broken-down Construction Activities into different Scopes of Work which are represented by Work Types. The Work Types are two-letter abbreviations which signify the different scopes of work.

When a DOB Application is prepared, it is necessary to check-off the Work Types you are filing for. When an Alteration Type-II or Alteration Type-III is filed, it is also necessary to specify the Construction Cost of each Work Type on the application.

Below is a list of the DOB Work Types. Note that the Work Types are pre-defined, and cannot be invented by the User. If the Work you are performing cannot be classified under one of the available Work Types, it will be necessary to use the OT (other) Work Type, and to provide a Description of the Other.

Each of the Work Types have unique Approval, Permit, and Signoff requirements associated with them. List of Work Types, as found on the PW-1 or PC-Filing Program:

BL Boiler
EQ Construction Equipment
FA Fire Alarm
FB Fuel Burning
FP Fire Suppression
FS Fuel Storage
MH Mechanical/HVAC
OT Other, General Construction, Structural, Interior Demolition
PL Plumbing
SD Standpipe
SP Sprinkler

Temporary versus Final Certificates of Occupancy

Q: What items are required for the issuance of a Temporary Certificate of Occupancy (TCO), versus a Final Certificate of Occupancy (FCO)? What items are required to renew an existing Temporary Certificate of Occupancy?

A: Below is a general list of items required for Temporary and Final Certificates of Occupancy. Additional items may be required:

Initial Temporary Certificate of Occupancy:
-Construction Signoff
-Plumbing Signoff (including Sprinkler & Standpipe)
-Elevator Signoff
-Technical Report TR-1's for Certification of all Completed Inspections
-Folder Microfilm
-Carbon Monoxide Detector Affidavit
-$100 DOB Temporary Certificate of Occupancy fee
-Fire Alarm FDNY Letter of Approval, or Self-Cert of Defects, or Fire Guards with Recon.
-OK from Commissioner (Certain Boroughs)

TCO Renewals:
-Construction Signoff (less than 18 months old or Update is required)
-Plumbing Signoff
-Elevator Signoff
-Show Progress of removal of Local Law Violations (eg: LL10/81 Elevator; LL 62/91 Boiler)
-Carbon Monoxide Detector Affidavit
-$100 DOB TCO Renewal Fee
-OK from Commissioner (Certain Boroughs)

Final Certificate of Occupancy:
-Construction Signoff
-Plumbing Signoff
-Elevator Signoff
-Electrical Signoff
-Carbon Monoxide detector Affidavit
-No Open Violations
-All Required Items entered as Received
-Waiver of Open, Unrelated Applications, if applicable.

Construction Fence Work Permits

Q: Why do Construction Fence Work Permits Expire on the last day of the year? (12/31)

A: Construction Fence (and other Construction Equipment, or EQ) Work Permits expire on the last day of the year, because the General Contractor's Street Obstruction Bond usually expires on the last day of the year. The Street Obstruction Bond must be active under General Contractor's Tracking Number for Construction Equipment (EQ) Work Permits. Renewal of Fence Permits requires updating the GC's Tracking Number with an updated Continuation Bond for the next calendar year.

Fire Rating Between Tenants?

Q: What is the minimum required fire rating for partitions between tenants of the smae Occuancy Group (eg: between two Apartments)?

A: A minimum one-hour rated fire separation is required between Tenants of the same Occupancy Group, per Building Code Section 27-341(a)

What is a Seismic Joint?

Q: What is a Seismic Joint?

A: Pursuant to Local Law 17/1995, a Building Separation (seismic joint) is required for all new construction adjoining existing construction. One inch (1") of separation is required for every fifty feet (50') of building height. This separation does not create a non-compliant side yard.

When proposed work consists of enlargement of an existing structure, compliance is required when new foundations are constructed, or when existing foundations are reinforced for the new enlargement, or when the cost of alterations exceeds 60% of the building value.

What is an IMD or Interim Multiple Dwelling?

Q: What is an IMD or Interim Multiple Dwelling? What does this mean?

A: An IMD or Interim Multiple Dwelling is a non-residential building that has been occupied as a Residential Building, without a CO for Residential apartments. IMD's must be converted to legal Multiple Dwellings in accordance with the Loft Board.

From the Loft Board Website:
Loft buildings in New York City that meet the criteria set forth in the Loft Law (Multiple Dwelling Law Article 7-C) are covered by the law as "Interim Multiple Dwellings" (IMDs) and are under the Loft Board's jurisdiction.

Generally speaking, a building that meets the following criteria will be subject to the Loft Law:
1. The building possesses no residential certificate of occupancy pursuant to §301 of the Multiple Dwelling Law;
2. The building was used in the past for manufacturing, commercial or warehousing purposes;
3. There were three or more residential tenants living in separate apartments in the building in the 20-month period between April 1, 1980, and December 1, 1981 (the "statutory window period").

As of February 15, 2007 there are 395 IMD buildings in New York City. There is a list of the IMD Buildings on the Loft Board's Website. Also, the DOB Building Information System (BIS) will list the Property as "Loft Law: YES".

How to Calculate Sprinkler Fire Reserve Capacity?

Q: How do I calculate the required Fire Reserve Capacity of the Sprinkler System? Is it possible to obtain an OK from the Commissioner for a reduction in the Sprinkler Fire Reserve Capacity to 20 Minutes?

A: The required Sprinkler Fire Reserve Capacity is calculated as follows:
Gallons Per Minute (G.P.M.) * (square root of (Available Pressure/Required Pressure) * (Required Minutes)

Example: 280.12 GPM * (Square Root Of (53.37 Available Pressure/31.94 Required Pressure) * 40 Minutes= 14,185 Minimum Required Gallons of Reserve.

The figures in the above are obtained from the Sprinkler Hydraulic Calculations.

For a Reduction in the Fire Reserve, refer to Table RS17-2-2.1(B), Note 1: In existing Buildings only, the Commissioner may authorize reduction of storage to 20 minutes provided there are provisions for acceptable mechanical automatic means of makeup to the storage tank. Where 20 minutes storage cannot be achieved with existing storage facilities, alternative means of supply may be considered by the Commissioner. In any event, no Fire Reserve Storage Facility shall have less than 3500 Gallons.

Home Office?

Q: Is a Home Office or Home Occupation allowed within a Dwelling Unit? Is the Home Occupation Use regarded as a Commercial Use? What are the limitations?

A: Home Occupation (a Home Office) is permitted within a Dwelling Unit subject to limitations. A Home Occupation is regarded as an Accessory Use to the Residential Apartment. The Home Occupation:
1. Must be carried on within the Dwelling Unit.
2. Is Limited to One Employee not residing within the Dwelling Unit.
3. Shall Occupy not more than 25% of the Dwelling Unit, or 500 sq ft of the Dwelling Unit, whichever is less.

These Home Occupations typically are small professional offices. If frequented by the Public, Handicap Accessibility may be required.

Home Occupations may include:
Fine arts studios, Professional offices, Teaching of not more than four pupils simultaneously,or, in the case of musical instruction, of not morethan a single pupil at a time.

Home Occupations may not include:
Advertising or public relations agencies, Barber shops, Beauty parlors, Commercial stables or kennels,Depilatory, electrolysis , or similar offices, Interior decorators' offices or workshops, Ophthalmic dispensing, Pharmacy, Real Estate or Insurance Offices, Stockbroker's Offices

Also Not Permitted:
Sales of articles produced elsewhere than on the premises, exterior displays, displaying exterior signage (except a nameplate for practice of a profession), producing offensive noises, vibration, etc.

See Definition of Home Occupation in the NYC Zoning Resolution for additional information.