Decks

What is the code for a roof deck above an extension?

I understand that a free standing deck can only protrude 8 feet from the face of the building, but what are the regulations for building a deck on the roof of an existing (and legal) one story extension? Our current extension is 12 feet wide by 11 feet deep and we would ideally like to…

by PHfamily
12/03/2008

I understand that a free standing deck can only protrude 8 feet from the face of the building, but what are the regulations for building a deck on the roof of an existing (and legal) one story extension? Our current extension is 12 feet wide by 11 feet deep and we would ideally like to cover that entire area with a deck and then a staircase down to the garden. We will certainly run things past our architect for the filing, but I would rather start planning what we want now and contact him when we are ready to embark on another renovation project.

Decks

Comments

  1. I recently added a deck on top of my rear yard cellar level extension and was fully approved by the building department. they count the 8 feet projection starting from the extension. you must maintain 3 feet minimum from the adjacent properties. the materials could be wood. i used pressure treated lumber for framing and ipe for the finish deck, and pressure treated lumber for the rails. your rails must be a minimum of 42″ above the finish deck. you must have a stamped drawing from an architect or professional engineer and the deck must withstand the minimum dead and live loads. [ framing must be substanial ] i used 2″ x 12″ pressure treated joist spaced 16″ on center. i can refer you the the engineer who designed and filed my drawings. [ it will run you minimum of 4k ]

  3. Technically, this is a roof. You are allowed to cover 1/3 of a roof with a non-combustible material such as pavers, or 1/5 of a roof with a combustible material (i.e., wood). What I often recommend is to cover 1/5 of the roof with a combustible material and then put down pavers to bring you up to 1/3]. Of course given that your extension is only 132 sq. ft., you’re not going to get much of a deck if you follow the code.

  5. Wow, jp2—I’ve never heard “terrace” applied to outdoor spaces above extensions in any brownstone neighborhood, but I don’t even qualify as an amateur regarding these matters. Based on your note I found these, which certainly interested me:
    http://www.nyc.gov/html/dob/html/reference/tppn0403.shtml
    http://curbed.com/archives/2008/02/14/dob_orders_bleecker_street_terrace_massacre.php
    Glad for additional info, and absolutely agree re: basics—speak with an architect.

  6. this is tricky if a deck is on top of an existing structure its not technically a deck but a terrace and therefore subject to a different set of criteria. Also projection into the minimum rear yard setback is an issue and if you get a ballbuster plan examiner they wont let you have the stair. Ill stop with the free information now, ask your architect.

  7. Nearly every one of my neighbors has an outdoor space built on the roof of their extension. However, when we undertook some rear facade work that required photo documentation to Landmarks, our expediter commented that nearly all these decks would be found illegal. My impression is that this was based mostly on the material used, and the lack of 3′ clearance between property line of adjoining properties. Weight is a major consideration when installing decks above existing extensions. Personally, I think this is better discussed with your architect than puzzled out on your own. Be sure to discuss what is commonly encountered v. what is letter of the law.

  8. Thanks Vinca. It also says that you can’t have “storage” space below, but we have an entire existing room……has anyone else built a deck on top of an existing extension? It seems like this applies to an entirely new structure for a deck system…

  • Get started on

    your next project

    Find a Pro