Roof deck requirements? Can I use a pedestal system? PVC roofing?

I am about to install a new roof over the current membrane. I would eventually like to use it as a roof deck. From what I understand, the regulations make this somewhat tricky–only 300 s/f can be decked; non-flammable materials muse be utilized in the first 3 feet of lot-line etc. My roof is around 1100 s/f split over two levels. I could crane up some steel joists and attach to my parapet but I would be left with large sections of the roof un-decked. Since this is our only outdoor space, I want to maximize its use. I could use the pedestal system like bison but I am not sure they are code compliant. Has anyone used these on a roof deck? I am about to get a new roof membrane and I am afraid the pedestal system will put too much stress. Another possibility is upgrading to a pvc roof that would allow foot traffic without fear of tearing the membrane and causing premature leaks. Any advice or thoughts would be appreciated. I know I have to go through an engineer and architect but I like to get as much information so I know what questions to ask. Thanks

misconformist

in Roofers 11 years and 4 months ago

Please log in, in order to post replies!

9 replies

Newest Oldest

cserman | 11 years and 4 months ago

string(1) "1"
object(WP_User)#4928 (8) {
  ["data"]=>
  object(stdClass)#4916 (12) {
    ["ID"]=>
    string(6) "181172"
    ["user_login"]=>
    string(7) "cserman"
    ["user_pass"]=>
    string(34) "$P$B.6rnUXn3NqXyeDDfCFjYUDZTZUHHI1"
    ["user_nicename"]=>
    string(7) "cserman"
    ["user_email"]=>
    string(29) "cserman@sermanengineering.com"
    ["user_url"]=>
    string(0) ""
    ["user_registered"]=>
    string(19) "2017-08-10 13:44:14"
    ["user_activation_key"]=>
    string(0) ""
    ["user_status"]=>
    string(1) "0"
    ["display_name"]=>
    string(7) "cserman"
    ["spam"]=>
    string(1) "0"
    ["deleted"]=>
    string(1) "0"
  }
  ["ID"]=>
  int(181172)
  ["caps"]=>
  array(1) {
    ["bbp_participant"]=>
    bool(true)
  }
  ["cap_key"]=>
  string(15) "wp_capabilities"
  ["roles"]=>
  array(1) {
    [0]=>
    string(15) "bbp_participant"
  }
  ["allcaps"]=>
  array(1) {
    ["bbp_participant"]=>
    bool(true)
  }
  ["filter"]=>
  NULL
  ["site_id":"WP_User":private]=>
  int(1)
}

As Jcarch said above, the main reason why the roofs usually cannot support a roof deck is because of the additional weight of decking and higher live loads than a typical floor. Also, roof joists are usually spaced farther apart than the typical floor joist and often are a little bit smaller. CS www.sermanengineering.com

aninspector | 11 years and 4 months ago

string(1) "1"
object(WP_User)#4927 (8) {
  ["data"]=>
  object(stdClass)#4926 (12) {
    ["ID"]=>
    string(5) "31438"
    ["user_login"]=>
    string(11) "aninspector"
    ["user_pass"]=>
    string(34) "$P$BUCy171hRMOCytjNBq99zggVSH8GZT/"
    ["user_nicename"]=>
    string(16) "an-inspector-2-2"
    ["user_email"]=>
    string(22) "2inspect@optonline.net"
    ["user_url"]=>
    string(37) "http://AberdeenBuildingConsulting.com"
    ["user_registered"]=>
    string(19) "2017-08-17 21:28:20"
    ["user_activation_key"]=>
    string(0) ""
    ["user_status"]=>
    string(1) "0"
    ["display_name"]=>
    string(28) "Aberdeen Building Consulting"
    ["spam"]=>
    string(1) "0"
    ["deleted"]=>
    string(1) "0"
  }
  ["ID"]=>
  int(31438)
  ["caps"]=>
  array(1) {
    ["bbp_participant"]=>
    bool(true)
  }
  ["cap_key"]=>
  string(15) "wp_capabilities"
  ["roles"]=>
  array(1) {
    [0]=>
    string(15) "bbp_participant"
  }
  ["allcaps"]=>
  array(1) {
    ["bbp_participant"]=>
    bool(true)
  }
  ["filter"]=>
  NULL
  ["site_id":"WP_User":private]=>
  int(1)
}

In row houses, the bearing walls, which run front-to-back separating stairwells from living spaces, often have shrunk in height. This is largely what accounts for the slopes in the floors as well as the increase of severity of the slopes on the higher floors from compound shrinkage. The bearing wall has often lost contact with the roof deck as a result of getting shorter. This is one of the reasons why roof decks need reinforcement when using for a deck.

dazednconfused2 | 11 years and 4 months ago

string(1) "1"
object(WP_User)#4923 (8) {
  ["data"]=>
  object(stdClass)#4929 (12) {
    ["ID"]=>
    string(6) "209624"
    ["user_login"]=>
    string(15) "dazednconfused2"
    ["user_pass"]=>
    string(34) "$P$BghKLTB3pwiNsI5BhQ/fSb/bBQWxiL0"
    ["user_nicename"]=>
    string(15) "dazednconfused2"
    ["user_email"]=>
    string(22) "un.perceived@gmail.com"
    ["user_url"]=>
    string(0) ""
    ["user_registered"]=>
    string(19) "2024-07-04 18:01:21"
    ["user_activation_key"]=>
    string(0) ""
    ["user_status"]=>
    string(1) "0"
    ["display_name"]=>
    string(15) "dazednconfused2"
    ["spam"]=>
    string(1) "0"
    ["deleted"]=>
    string(1) "0"
  }
  ["ID"]=>
  int(209624)
  ["caps"]=>
  array(1) {
    ["bbp_participant"]=>
    bool(true)
  }
  ["cap_key"]=>
  string(15) "wp_capabilities"
  ["roles"]=>
  array(1) {
    [0]=>
    string(15) "bbp_participant"
  }
  ["allcaps"]=>
  array(1) {
    ["bbp_participant"]=>
    bool(true)
  }
  ["filter"]=>
  NULL
  ["site_id":"WP_User":private]=>
  int(1)
}

yes, you can, providing the steel is sized correctly for the load and the span.

misconformist | 11 years and 4 months ago

string(1) "1"
object(WP_User)#4928 (8) {
  ["data"]=>
  object(stdClass)#4930 (12) {
    ["ID"]=>
    string(6) "176755"
    ["user_login"]=>
    string(13) "misconformist"
    ["user_pass"]=>
    string(34) "$P$BiPpfSI8Yq8HlraTetzIQx6nf6HgOE1"
    ["user_nicename"]=>
    string(13) "misconformist"
    ["user_email"]=>
    string(22) "yasseraggour@yahoo.com"
    ["user_url"]=>
    string(28) "/forums/users/misconformist/"
    ["user_registered"]=>
    string(19) "2017-08-10 14:25:48"
    ["user_activation_key"]=>
    string(0) ""
    ["user_status"]=>
    string(1) "0"
    ["display_name"]=>
    string(13) "misconformist"
    ["spam"]=>
    string(1) "0"
    ["deleted"]=>
    string(1) "0"
  }
  ["ID"]=>
  int(176755)
  ["caps"]=>
  array(2) {
    ["subscriber"]=>
    bool(true)
    ["bbp_participant"]=>
    bool(true)
  }
  ["cap_key"]=>
  string(15) "wp_capabilities"
  ["roles"]=>
  array(2) {
    [0]=>
    string(10) "subscriber"
    [1]=>
    string(15) "bbp_participant"
  }
  ["allcaps"]=>
  array(4) {
    ["read"]=>
    bool(true)
    ["level_0"]=>
    bool(true)
    ["subscriber"]=>
    bool(true)
    ["bbp_participant"]=>
    bool(true)
  }
  ["filter"]=>
  NULL
  ["site_id":"WP_User":private]=>
  int(1)
}

Thanks for these helpful responses. Do you know if I can I use a light-guage steel track and joist system?

dazednconfused2 | 11 years and 4 months ago

string(1) "1"
object(WP_User)#4927 (8) {
  ["data"]=>
  object(stdClass)#4931 (12) {
    ["ID"]=>
    string(6) "209624"
    ["user_login"]=>
    string(15) "dazednconfused2"
    ["user_pass"]=>
    string(34) "$P$BghKLTB3pwiNsI5BhQ/fSb/bBQWxiL0"
    ["user_nicename"]=>
    string(15) "dazednconfused2"
    ["user_email"]=>
    string(22) "un.perceived@gmail.com"
    ["user_url"]=>
    string(0) ""
    ["user_registered"]=>
    string(19) "2024-07-04 18:01:21"
    ["user_activation_key"]=>
    string(0) ""
    ["user_status"]=>
    string(1) "0"
    ["display_name"]=>
    string(15) "dazednconfused2"
    ["spam"]=>
    string(1) "0"
    ["deleted"]=>
    string(1) "0"
  }
  ["ID"]=>
  int(209624)
  ["caps"]=>
  array(1) {
    ["bbp_participant"]=>
    bool(true)
  }
  ["cap_key"]=>
  string(15) "wp_capabilities"
  ["roles"]=>
  array(1) {
    [0]=>
    string(15) "bbp_participant"
  }
  ["allcaps"]=>
  array(1) {
    ["bbp_participant"]=>
    bool(true)
  }
  ["filter"]=>
  NULL
  ["site_id":"WP_User":private]=>
  int(1)
}

The decking can be wood on a roof deck/terrace if it’s less than 20% of the entire roof area, which is what JCArch was referring to. Also note that the PVC suggested is not non-combustible, so is not allowed on more than 20% of the roof.

arch007 | 11 years and 4 months ago

string(1) "1"
object(WP_User)#4930 (8) {
  ["data"]=>
  object(stdClass)#4923 (12) {
    ["ID"]=>
    string(5) "29788"
    ["user_login"]=>
    string(7) "arch007"
    ["user_pass"]=>
    string(34) "$P$BmUayxc5ELlzTIdlUTyRSsuBuiKM24."
    ["user_nicename"]=>
    string(7) "arch007"
    ["user_email"]=>
    string(16) "master@gmail.com"
    ["user_url"]=>
    string(34) "http:///forums/users/architect777/"
    ["user_registered"]=>
    string(19) "2017-08-10 14:16:38"
    ["user_activation_key"]=>
    string(0) ""
    ["user_status"]=>
    string(1) "0"
    ["display_name"]=>
    string(7) "arch007"
    ["spam"]=>
    string(1) "0"
    ["deleted"]=>
    string(1) "0"
  }
  ["ID"]=>
  int(29788)
  ["caps"]=>
  array(2) {
    ["subscriber"]=>
    bool(true)
    ["bbp_participant"]=>
    bool(true)
  }
  ["cap_key"]=>
  string(15) "wp_capabilities"
  ["roles"]=>
  array(2) {
    [0]=>
    string(10) "subscriber"
    [1]=>
    string(15) "bbp_participant"
  }
  ["allcaps"]=>
  array(4) {
    ["read"]=>
    bool(true)
    ["level_0"]=>
    bool(true)
    ["subscriber"]=>
    bool(true)
    ["bbp_participant"]=>
    bool(true)
  }
  ["filter"]=>
  NULL
  ["site_id":"WP_User":private]=>
  int(1)
}

The city may accept Bison out of ignorance. The panels are fire rated but the plastic pedestals are not…something the manufacturer will not talk about. The 3′ rule does not apply to roofs, the entire deck must be Class A I like the Bar joist idea…you will need a mini stair to get up to the higher level of the deck. http://nyc-dob.com

BSDOD | 11 years and 4 months ago

string(1) "1"
object(WP_User)#4931 (8) {
  ["data"]=>
  object(stdClass)#4928 (12) {
    ["ID"]=>
    string(5) "81246"
    ["user_login"]=>
    string(5) "BSDOD"
    ["user_pass"]=>
    string(63) "$wp$2y$10$.OsmxvjaeA121WsOWmpAqePEevkc22uJ0FZbVpsdYeM3BY4gIhuu."
    ["user_nicename"]=>
    string(5) "BSDOD"
    ["user_email"]=>
    string(18) "apoprilo@gmail.com"
    ["user_url"]=>
    string(19) "/forums/users/apop/"
    ["user_registered"]=>
    string(19) "2010-10-21 00:43:10"
    ["user_activation_key"]=>
    string(0) ""
    ["user_status"]=>
    string(1) "0"
    ["display_name"]=>
    string(4) "Apop"
    ["spam"]=>
    string(1) "0"
    ["deleted"]=>
    string(1) "0"
  }
  ["ID"]=>
  int(81246)
  ["caps"]=>
  array(2) {
    ["subscriber"]=>
    bool(true)
    ["bbp_participant"]=>
    bool(true)
  }
  ["cap_key"]=>
  string(15) "wp_capabilities"
  ["roles"]=>
  array(2) {
    [0]=>
    string(10) "subscriber"
    [1]=>
    string(15) "bbp_participant"
  }
  ["allcaps"]=>
  array(4) {
    ["read"]=>
    bool(true)
    ["level_0"]=>
    bool(true)
    ["subscriber"]=>
    bool(true)
    ["bbp_participant"]=>
    bool(true)
  }
  ["filter"]=>
  NULL
  ["site_id":"WP_User":private]=>
  int(1)
}

Dorkofwindsor, I’ve often wondered the same thing, but if I can recall, when my house was gutted the stiffening wall didn’t go all the way to the roof. Walking on my floors are pretty solid, but I feel a bit of ounce on the roof

dorkofwindsor | 11 years and 4 months ago

string(1) "1"
object(WP_User)#4927 (8) {
  ["data"]=>
  object(stdClass)#4932 (12) {
    ["ID"]=>
    string(6) "176774"
    ["user_login"]=>
    string(13) "dorkofwindsor"
    ["user_pass"]=>
    string(34) "$P$Bov.472kQmY8OGlKN.dDXa5nt5gnOG0"
    ["user_nicename"]=>
    string(13) "dorkofwindsor"
    ["user_email"]=>
    string(23) "dorkofwindsor@yahoo.com"
    ["user_url"]=>
    string(28) "/forums/users/dorkofwindsor/"
    ["user_registered"]=>
    string(19) "2017-08-10 14:25:48"
    ["user_activation_key"]=>
    string(0) ""
    ["user_status"]=>
    string(1) "0"
    ["display_name"]=>
    string(13) "dorkofwindsor"
    ["spam"]=>
    string(1) "0"
    ["deleted"]=>
    string(1) "0"
  }
  ["ID"]=>
  int(176774)
  ["caps"]=>
  array(2) {
    ["subscriber"]=>
    bool(true)
    ["bbp_participant"]=>
    bool(true)
  }
  ["cap_key"]=>
  string(15) "wp_capabilities"
  ["roles"]=>
  array(2) {
    [0]=>
    string(10) "subscriber"
    [1]=>
    string(15) "bbp_participant"
  }
  ["allcaps"]=>
  array(4) {
    ["read"]=>
    bool(true)
    ["level_0"]=>
    bool(true)
    ["subscriber"]=>
    bool(true)
    ["bbp_participant"]=>
    bool(true)
  }
  ["filter"]=>
  NULL
  ["site_id":"WP_User":private]=>
  int(1)
}

jcarch, i’m not the OP but i was wondering recently why someone like me might need steel beams when my house’s joists are the exact same size and spacing as all of my other floors, each of which has kitchens and baths. The only thing that seems different is the ‘subfloor’ of the roof. Over the years as i dream of a roof deck myself i was wondering why beams over parapet when it structurally seems just like another floor? Many thanks for listening, i had a structural engineer tell me once that the roof would need reinforcing but i couldn’t get any more of a detailed answer out of him.

jcarch | 11 years and 4 months ago

string(1) "1"
object(WP_User)#4930 (8) {
  ["data"]=>
  object(stdClass)#4933 (12) {
    ["ID"]=>
    string(5) "23991"
    ["user_login"]=>
    string(6) "jcarch"
    ["user_pass"]=>
    string(34) "$P$BS0hz8fYZfWVNwJxAdb5D7GSB6JTfb."
    ["user_nicename"]=>
    string(6) "jcarch"
    ["user_email"]=>
    string(22) "jpc@jcarchitecture.com"
    ["user_url"]=>
    string(21) "/forums/users/jcarch/"
    ["user_registered"]=>
    string(19) "2017-08-10 14:06:39"
    ["user_activation_key"]=>
    string(0) ""
    ["user_status"]=>
    string(1) "0"
    ["display_name"]=>
    string(6) "jcarch"
    ["spam"]=>
    string(1) "0"
    ["deleted"]=>
    string(1) "0"
  }
  ["ID"]=>
  int(23991)
  ["caps"]=>
  array(2) {
    ["subscriber"]=>
    bool(true)
    ["bbp_participant"]=>
    bool(true)
  }
  ["cap_key"]=>
  string(15) "wp_capabilities"
  ["roles"]=>
  array(2) {
    [0]=>
    string(10) "subscriber"
    [1]=>
    string(15) "bbp_participant"
  }
  ["allcaps"]=>
  array(4) {
    ["read"]=>
    bool(true)
    ["level_0"]=>
    bool(true)
    ["subscriber"]=>
    bool(true)
    ["bbp_participant"]=>
    bool(true)
  }
  ["filter"]=>
  NULL
  ["site_id":"WP_User":private]=>
  int(1)
}

The 300 s.f. limitation is only for combustible materials. If you want a larger deck, you’d need to use stone or concrete, but then can cover the whole roof. We’ve used bison pedestals in the city w/out any problems. Bison makes square pads that the pedestals can sit on – these spread the weight at each point around over a larger area than the pedestal alone. It’s unlikely that your existing roof can handle the increased loads of a roof deck. People, pavers, planters, etc. weigh quite a bit, and roofs, especially ones on older buildings, are not designed to handle that extra weight. And by code you have to design for higher loads for a roof deck compared to a roof, so you’ll likely need to go with your steel beam between the parapets idea. PVC idea sounds good, but the wear and tear of using this as an active area is not a good idea…you’ll damage the membrane eventually, and you’d also have a sloping deck. Remember to think about how you’ll get up there, and how you’ll install a code compliant railing all the way around the deck. jcarch ———————— James Cleary Architecture brownstoner.staging.wpengine.com/jamescleary

Roof deck requirements? Can I use a pedestal system? PVC roofing?

How the Trump Tax Bill Changes NYC Solar

Affordable Housing Lottery Opens for Luxury ‘Burg Build, With Units From $1,880

Daily Links: Pedestrian Deaths Remain High in Brooklyn While City Sees Drop

Brooklyn Real Estate Listings Six Months Later: Three Sold, One Still Available

Roof deck requirements? Can I use a pedestal system? PVC roofing?

NEIGHBORHOODS