Replies

1. 
   Piffin | Mar 30, 2009 02:51am | #1

   That gets tricky if the underlying framing hasn't been preplanned and prepared for it and if there is no deck being built to protect the roof.

   What kind of roofing material is on it and how old?

    

    

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1. 
   billc916 | Mar 30, 2009 02:57am | #2

   It is probably at least 30 years old tar roof . The roofer is planning to put down a mop installed Ribberoid roof pver the existing as it does not leak or have any flat spots where water settles after rain. Thanks

1. 
   Piffin | Mar 30, 2009 03:15am | #4

   In that case, you can open it up to place framing to attach to, patch the spots, then seat metal brackets such as Simpsons or custom wider flange ones, then have the roofer install pitch pans around the posts, then trim over with cedar.OrYou could look into the type of hardware Fypon uses that makes up a torsion box, seat that flange in tar and lag it down, then have him roof over the hardware, then mount the posts on the all thread.There are other options, but there is no truly good way to mount posts on a roof and expect as much strength as on a deck and as waterproof as an unpenetrated roof 

    

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2. 
   ponytl | Mar 30, 2009 03:10am | #3

   if you can do a welded metal rail system... then you can weld it into one piece...with flat metal pads on the corners an mid posts set onto pads of torchdown and attach it at the 2 walls you have...  with a 1.5" pipe top & bottom rail... it isn't going anywhere...

   p

1. 
   Piffin | Mar 30, 2009 03:17am | #5

   Good thought - no penetrations in the roof membrane 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

3. 
   JerraldHayes | Mar 31, 2009 02:17am | #6

   Hello Bill, when you say the railing runs around three sided of the roof are you then saying it terminates at two points into a second story exterior wall? If that is the case I have a post I first wrote here back in 2002 that might address your situation. I repost it again here with some minor editing

   If at all possible we DON’T attach our post to the roof deck or roof deck

   framing.

   I've done a little bit of forensic analysis on the exterior railings I've worked

   on over the years and on one of the first railing that I ever worked on four

   of the roof deck ceiling joists that the original railing post were attached

   to had to be repaired because where the deck joists were attached to the railing

   post moisture moving down the post and sitting between the post and joist had

   rotted the joist right through. We pulled up all the roof decks sheathing (

   and replaced it) and sistered new joists to the old ones but I learned a few

   lessons from working that project that I've applied to how we try and do things

   today.

   1. If you can avoid penetrating the roof membrane in anyway AVOID IT!
   2. If you have to penetrate the roof membrane but can avoid penetrating the

      roof deck AVOID IT TOO!

   The railing roof deck railing on the project below is not attached to the roof deck anywhere

   at all. Being wrap-around-shaped (see the plan view below) the railing is attached

   to the exterior walls of the house by concealed hanger bolts typically used

   to connect railing fitting but the posts really just sit on the roof deck and

   are held down by the weight of the whole railing assembly. Well almost...

   View Image

   Actually each of the 4x4 posts on this project has a 3/8"x16"x16"

   PT plywood "foot" fastened to the post by 4 stainless steel screws. The

   foot is then "glued" to the roof membrane (single ply miodified-bitumen)

   with roofing cement and then a 2'x2' piece of of the membrane was slipped over

   the top of the post and then torch heat welded down. The foot keeps the railing

   from wobbling and it could have been screwed down (although on this project

   it wasn't) to stiffen it further. To keep the whole thing straight the top rails

   were made by laminating two 1x4s together with epoxy and staggering the lap

   joints so there was one 18' one-piece rail returning to the house and two one-piece

   continuous 40' rail sections one along the the other wrapping around the side

   of the house and ending in front with another 20 return to the house. See the

   plan view sketch below.

   View Image

   Since the roof deck was covered with gravel after the whole thing was done

   the hump around the bottom of the posts was masked by the gravel. When the roof

   deck needs to be flush we make the foot piece the same as the roof deck sheathing

   and then cut the sheathing out where the post needs to be and plop the post

   down flush. When we do do our post flush like that they are penetrating the

   membrane so we use a flashing and construction technique that I picked up reading

   an article in Fine HomeBuilding years ago by Scott McBride entitled Railing

   Against the Elements (Issue #70 Oct/Nov 1991).

   The key thing I picked up from that article was the flashing detail around

   a post and then slipping another box post over the first that serves as counter

   flashing to the base flashing. I've seen that same detail in another FHB article

   although the name and issue of the article escapes me right now.

   All this is not to say that we never pass through the roof membrane with our

   posts or never fasten our posts to the framing but we do try to avoid that if

   at all possible and if we can engineer an alternative solution. Each place a

   post penetrates the membrane represents a potential leak and each place a post

   passes through the roof deck represents a potential for setting up a channel

   for any leak to follow into the insulated ceiling space so we try very hard

   to avoid those potential problems.

   There are some other variations on the technique I've described above that

   we've used in other various situations and conditions but I think that's enough

   for now to illustrate my point and our technique.

   One other plus to our methods versus attaching the posts to the joists and

   other framing is it's a major labor time-saver too which can add to your bottom

   line. If you do have to attach the posts to framing to get the rigidity you

   need I would suggest you keep the number of penetrations to a bare minimum.

   Good luck and be sure to tell us what you find regarding how the old railing

   was secured to the structure.

   Hope that helps and give you another opinon on how to approach roof deck railings.

   ---

   View Image

1. 
   billc916 | Mar 31, 2009 03:38am | #8

   Thanks I did notice the original posts had a metal "foot" around them about an inch tall and they look like they were fastened to the roof and then tarred over. I know the house is 90 years old but I am sure the railing is less than 30 years old. Thanks., bill c.

4. 
   AitchKay | Mar 31, 2009 02:28am | #7

   I think Scott McBride did a nice article in FHB on one he built. Quite a while back. I'll let someone who's got the disk find it for you.

   That said, here's another vote for monolithic steel, whether you box it out with wood or not.

   I don't like roof penetrations.

   AitchKay

1. 
   ponytl | Mar 31, 2009 03:58am | #9

   you know i like steel...

   i did a deck 3ft above a flat roof  where i fastened 3" round steel posts to the  framing below the roof  where i came through the roof i used standard flashing boots (metal & rubber) like you would use for any vent pipe come'n through the roof...  they allow the pipes to move a bit and still keep everything sealed...

   since i welded flanges on the pipe  for mounting to the frame work... and holding the deck support joists... and flanges for the deck rail... i had to slide the boots on the post during fabrication... then slid them down to the roof for sealing...  has worked well for about 4 years... ( i might have been able to streach the rubber over the lower flange after but wasn't worth the risk of tear'n em)

   p