Adding a Roof Deck in NYC

Building a Roof Deck in NYC

When adding a roof deck to a building in NYC, you will need an architect to design it and file for permits with the NYC DOB. Roof Decks must comply with egress, accessibility, Building, and Zoning Codes.

The first thing I tell people planning to build a roof deck is that making the deck is not as easy as they think it is. Many other issues are involved, such as permitting, structural considerations, accessibility, safety, and guardrails, that add complexity.

I am Jorge Fontan, an architect in New York and owner of the Manhattan-based architecture firm Fontan Architecture. In this post, I will review a few basic concepts regarding the logistics and bureaucracy for building a roof deck in NYC while showing a few pictures from our projects.

 

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 through an Alt CO (formerly Alt 1) or Alteration (Formerly Alt 2). An Alteration CO requires a new Certificate of Occupancy, whereas a more straightforward application of Alteration does not. Both require a New York Registered Architect to file with the DOB.

 

Alteration Without CO for Decks

In order to file a Roof Deck as an Alteration without needing a new Certificate of Occupancy, the following requirements must be met:

• The new rooftop terrace or deck is for “Passive Recreation” and is an 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 contradicting the Certificate of Occupancy listed live load.

If these requirements are not met, you will file an Alt CO. This application will take longer as it requires a more extensive review and an additional CO inspection.

 

NYC Roof Deck Codes

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. 
• 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 for this type of project. No exceptions.
• The roof must comply with all exit and egress requirements.
• Railings or Parapets must be 42.”
• 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 requirement 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, structural analysis is one of the first steps. The roof must support the structure, decking, and building components, known as the dead load. As well it must support the prescriptive live load. Live load varies based on use and as specified in the Building Code.

The live loads for roof decks are higher than roofs typically require; therefore, you must have a structural analysis performed on the roof. An accessory roof deck live load will normally be 1.5 times the live load of the primary Building Use it is accessory too. If the roof cannot support the live load, it must be reinforced or rebuilt to accommodate the necessary live load. For example, a Residential Building has a live load minimum requirement of 40 pounds per square foot. A roof deck on a residential building, therefore, requires a live load capacity of 60 pounds per square foot.

NYC Building Code Roof Deck regulations require structural plans and calculations to be filed whether or not structural work is needed.

 

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 option 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 Decks 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 has an occupancy of 75 or more, it will also need a new Certificate of Occupancy and an Alteration CO 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 weak 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. You will need to build a mock-up for LPC approval of any additions, such as railings or parapets.

 

NYC Roof Deck Materials

One of the most important things for your Roof Deck Design is materials. Let’s put all decking materials into two categories: combustible and noncombustible.

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 two-foot x two-foot squares. Porcelain is also an example of a noncombustible roof decking material.

 

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 than have to fix problems later.

 

Roof Deck Pedestal Systems

These days we typically install roof pavers over a pedestal system. The photo below shows the installation of a pedestal and porcelain roof deck on one of our projects.

 

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 regard to NYC Roof Deck Regulations. This post does not assume to cover every possible issue or condition but provides a general overview of the topic.

 

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Thank you for reading our blog post on NYC Roof Deck Design.

I hope this was helpful. Contact us at Fontan Architecture directly if you want to speak with an architect about a potential project.

 

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