Adding a Roof Deck NYC(Last Updated On: September 25, 2019)
When adding a roof deck to a building in NYC you will file for permits with the NYC DOB. Roof Decks must comply with egress, accessibility, building codes, and zoning codes.
NYC Roof Deck Design
- NYC Roof Deck Regulations
- Structural Options
- Roof Deck Materials
- Roof Deck Drainage
- Green Roofs
NYC Roof Deck Regulations
Adding a roof deck to an existing building in NYC requires permits. All work must be filed with the NYC Department of Buildings (DOB). A roof deck would be filed with the DOB either through an Alteration Type 1 (Alt 1) or Alteration Type 2 (Alt 2). An Alteration Type 1 requires a new Certificate Of Occupancy whereas a simpler application of Alteration Type 2 does not. Both require a New York Registered Architect or Professional Engineer to file with the DOB.
Alteration Type 2 for Building a Roof Deck Regulations
In order to file a Roof Deck as an Alteration Type 2 the following requirements must be met:
- The new rooftop terrace or deck is for “Passive Recreation” and is accessory to a “principal use” within the building.
- The roof deck occupant load cannot exceed 74 people.
- Adding the roof deck would not require an increase in the number of exits based on occupancy calculations.
- No structural work would be required to increase the live loads that contradict the Certificate Of Occupancy listed live load.
If these requirements are not met you will file an Alteration Type 1. Alt 1s have higher requirements and will take longer.
Additional NYC Roof Deck Code
The following are additional code requirements for roof decks.
- Roof Decks with One Means of Egress for Apartment Buildings or Houses are limited to 30 people based on occupancy calculations.
- For certain Building Uses a roof deck would be considered floor area and may require enclosure. This will require an Alt 1 filing.
- Structural Plans must be filed with the NYC DOB including load calculations. Even if there is no need for structural work. No matter what you need a structural engineer on this type of project. No exceptions.
- The Roof must comply with all exit and egress requirements.
- If the building has an elevator or is subject to elevator requirements at least one elevator must access the roof. If there is no elevator to the roof one of the elevators must be extended. This is for ADA Accessibility, Americans With Disabilities Act.
NYC Building Code Structural Requirements for Decks
When planning to add a roof deck to an existing building one of the first steps is structural analysis. The roof must be able to support the decking, planters, and building components know as the dead load. As well it must support the prescriptive live load from the Building Code. Live loads are people. The live load for a roof deck are higher than roofs normally require therefor you must have a structural analysis performed on the roof.
An accessory roof deck live load will typically be 1.5 times the live load of the primary building use it is accessory to. If the roof cannot support the live load it must be reinforced or rebuilt in order to accommodate the necessary live load.
NYC Building Code Roof Deck regulations require structural plans and calculations to be filed whether or not structural work is required.
Adding Roof Deck Structure
There are a few ways to support a roof deck. One is to have the roof deck sit on the roof itself. This will not always be feasible. Sometimes the roof cannot support the higher live load requirements. If the roof cannot support the necessary load it must be reinforced, rebuilt, or an alternative support can be used. If the building has parapet walls the masonry parapets may be able to support the weight. Steel beams can run from the parapets above the actual roof and the deck can sit on the beams.
Place Of Assembly for Roof Deck Conversions With 75 People or More
Any roof deck or terrace with an occupancy of 75 people or more will require a Place of Assembly Filing. If the roof deck will have an occupancy of 75 or more it will also require a new Certificate Of Occupancy and an Alteration Type 1 filing. The occupancy is based on calculations from the building code.
NYC Building Code Roof Deck Parapets and Railings
Parapets and Railings on a roof deck must be at least 3′-6″ (42 inches). The existing parapet may be under that requirement or adding the roof deck may reduce the height of the parapet since the parapet is measured from the walking surface. In that case you will need to increase the height of the parapets by adding masonry or you can add metal railings. The railings can be mounted to the inside face of the parapet. Parapets are a week point for waterproofing problems so this work should be properly designed and installed.
If you are in a Landmark Building work on the parapets will need LPC approval.
NYC Roof Deck Materials
One of the most important things for your Roof Deck Design is materials. Lets put all decking materials into two categories combustible and non combustible materials.
NYC Building Code Roof Deck for Combustible Materials
Roof decking in combustible materials such as wood or rubber can only cover 20% of the roof.
You cannot have a wood roof deck over 20% of the roof area in NYC.
Noncombustible Roof Decks
Concrete Pavers are an example of noncombustible roof decks. These are usually 2 or 3 inches thick and come in 2 foot x 2 foot squares. Crushed gravel is also an example of a noncombustible roof decking material. Pavers are a really good choice for many reasons.
Advantages of Concrete Pavers for Roof Decks:
- Strong and Durable
- Can be removed allowing easy access for maintenance
- Come in many colors
- Will not be subject to uplift by strong wind loads
Roof Drainage and Waterproofing
Proper drainage and waterproofing are essential to your roof. When adding a deck you must be sure that the new deck does not interfere with proper drainage of the roof and does not damage the waterproofing materials. Building a roof deck is a big deal, don’t take it lightly. It is better to do it right the first time then have to fix problems later.
NYC Green Roofs and Roof Gardens
You may want to consider a Green Roof or Roof Garden. These can be as simple as some planters or more complex with large planing areas. New York State has a tax abatement for green roofs in NYC. Learn more in another post we wrote about the New York Tax Abatement for Green Roofs.
NYC Roof Deck Design
As an architect I study Building Codes and Zoning closely, but these are complicated and quite involved issues. In this article we reviewed some of the basic concepts with regards to NYC Roof Deck Regulations. 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 blog post on NYC Roof Deck Design.
I hope this was helpful. Please leave questions and comments below. If you would like to speak with an architect you can Contact Fontan Architecture directly.
Author Jorge Fontan AIA
This post was written by Jorge Fontan, a Registered Architect and owner of Fontan Architecture.