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Discussion Forum

railing posts through flat roof

Taylorsdad | Posted in Construction Techniques on June 22, 2009 05:37am

Hello, 1880’s farmhouse here with flat roof over first level 3-season room section of home. Looks like old rolled out membrane at about 42″ widths on roof that had a silver paint on it thats since flaked away. Client wants a structurally sound but decorative railing at perimeter. I’m thinking to cut an 8″ wide channel through the roofing and plywood sheathing (but not cut the joist below) and bolt p/t 4×4 to ceiling joists below. I get stuck when I consider how I will make the roof water tight again. Obviously I’d start with reapplying sheathing, etc.. in the channel, I just dont see how to keep the water from penetrating the area where the post goes through the roof.  Anyone successfully deal with such a situation before? Looking forward to someone smacking me in the head with the obvious answer – hopefully.

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Replies

  1. theslateman | Jun 22, 2009 05:42pm | #1

    Flash and counterflash the posts

     

    View Image
    1. Piffin | Jun 22, 2009 08:55pm | #3

      he's going to need more pictures.... 

       

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

    2. Taylorsdad | Jun 23, 2009 12:21am | #5

      Hey slateman, I like what you've got here. Thanks for taking the extra moment to provide your picture, which really puts the process right in front of me.  I think I can build on this (no pun intended).

      1. theslateman | Jun 23, 2009 01:16am | #7

        TD ,

        If you need more pictures I'd be happy to show you the whole process .

        That flashing can be used for any roof type , just varying the material used at the base .

        These posts were wrapped with mahogany later , but you could cut a reglet around all 4 sides and counterflash these flashing sleeves .

        Ask for more help from us if you feel you need it .

        Walter

        1. Taylorsdad | Jun 23, 2009 01:12pm | #10

          We just did a full rebuild of the room below and this is an add to the job. I told them we will be happy to do it as long as I'm comfortable with the flashing procedure, so I'd love to see what you have - especially if you have confidence in it.

          1. theslateman | Jun 23, 2009 08:43pm | #17

            TD ,

            Heres a link to an album showing the whole project that one picture came from .

            The sequence of wrapping the PT posts with copper is midway thru it .

            Yes I am most confident that with copper , flux and bar solder I can keep out water . Your mileage may vary somewhat .

            Walter

             

            http://share.shutterfly.com/action/welcome?sid=8cbsmrhq2V4&emid=sharshar&linkid=link5&cid=EMsharshar

      2. seeyou | Jun 23, 2009 02:43am | #8

        Hey slateman, I like what you've got here.

        Bet he wishes he had a quarter for everytime he's heard that.

        We're pouring some pitch pockets around some ipe posts tomorrow or the next day. I'll try to get some pix and post them. Stay tuned.http://www.quittintime.com/      View Image        

        1. Piffin | Jun 23, 2009 05:37pm | #14

          The problem with a pitch-pocket system is that when the 4x4 checks, you have a leak. 

           

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

          1. seeyou | Jun 23, 2009 07:46pm | #16

            We're counterflashing over the pitch pocket - or were. We've redesigned using Simpson post bases.http://www.quittintime.com/      View Image        

          2. Piffin | Jun 24, 2009 12:04am | #19

            Yah know what...The best way of dealing with this I have ever seen was a series of photos a guy here posted once 3-4 years ago - pretty sure it was since we got properoed.he had custome brackets welded up that looked about like the flash pan Walter showed, but of heavier metal and it was not for thru the roof, but was a pocket to hold the post like Simpson brackets do. His wide bottom flange made for good attachement and sealing in on the roof, and it was heavy dutyu enough to keep the post secure. I think he had drainage weeps in the side too. Wish i'd saved those photos to my hard drive. It was support bracket and flashing all in one. 

             

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

          3. Zorrohood | Jun 24, 2009 01:25am | #20

            I cleaned out all the Local Lowes when they were gonna disc. these, I have a few boxes of them.http://forums.taunton.com/n/docs/docDownload.aspx?guid=2DFBA3A9-EA94-457A-AB15-53DF7283C897&webtag=tp-breaktimewhuups...Dunno why that happened , try this...#2
            http://forums.taunton.com/n/docs/docDownload.aspx?guid=FFA6A7F6-23C4-477B-BD1D-5670E30E349E&webtag=tp-breaktimeEdited 6/23/2009 6:26 pm ET by Zorrohood

            Edited 6/23/2009 6:28 pm ET by Zorrohood

  2. Piffin | Jun 22, 2009 08:53pm | #2

    There is no way to keep a penetration like that from leaking.

    There are ways to do a railing and a leakproof roof together tho.

    Since this roof is already old enough to be on last legs, that will be part of it.

    What sort of decking you thinking of? Let's start there.

     

     

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

  3. MikeSmith | Jun 22, 2009 11:33pm | #4

    that's  typically  an  EPDM  roof  and  the  posts  get  flashed  with  uncured  rubber...

     

      see  my  thread    about  ##  Guest  Suite""   in  the  photo  gallery

    Mike Hussein Smith Rhode Island : Design / Build / Repair / Restore
    1. Taylorsdad | Jun 23, 2009 01:43pm | #12

      Mike, I finally had an oppty to hunt down the photo(s) u referred me to. Great example of what i need to achieve. Thanks, Bill.  FYI, I tried to upload a pic or two of the structure, I just cant seem to reduce the size of the photos.

  4. Piffin | Jun 23, 2009 12:36am | #6

    my comment eaar;lier was really short, but there is a reason.

    I klnow you are not way up on roofing/flashing skills. This is one of the more difficult things to do and get it right so it lasts for more than a few years.

    There are two ways to go about it. The way Walter and Mike are touching on is for skilled people with a history of experience in low slope roofs.

    And it will not work for a simple 4x4 post. You have to flash that as the primary post, then clad it with a hollow sheathe 67x6 post as the rim over it and a good water tight cap.

    And with all that, it is one of the more common things I have had to repair in my years roofing, because it all has to be done near perfect to keep water out. And it needs to be strong structurally also because if there is any wiggle in the post ( say from wear over the years or the post shrinks over time and the lags loosen up) then the watertight flashing is not necessarily water tight anymore.

    search the archives here for threads on the subject. There are lots of other ways to do this that are more forgiving for a novice or if you can't find anything, I can repeat them.

    Type of roofing you use will influence details of how you seal the flashing down too. And that selection will be important. For instance, EPDM is possible the best choice, but it is incompatible with bituminous roof materials. But I am not sure what it is you have now.

     

     

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

    1. User avater
      Jeff_Clarke | Jun 23, 2009 06:44am | #9

      "And it will not work for a simple 4x4 post. You have to flash that as the primary post, then clad it with a hollow sheathe 6x6 post as the rim over it and a good water tight cap"

      Exactly.   Ours uses a 4 x 4 through the roof but then a 12" x 12" hollow newel post is dropped over top.   PT 4 x 4 not only flashed/counterflashed but wrapped full-ht with Vycor too.

      Does NOT leak.

      Jeff 

      1. Taylorsdad | Jun 23, 2009 01:18pm | #11

        Since the client has no interest in having to sand/prime/paint again in the next few years, we've been leaning towards a composite application thus using a composite sleeve over the 4x4.  So heres what I was considering: take standard p/t 4x4 and rip it to nominal 3.25 x 3.25 so that it is then thin enough to accept something like a vycor wrap all around and then still accept the composite sleeve.  That is what I've cobbled together above the roof surface, its AT the roof surface that I'm reaching out to Breaktime. Any opinions on that?

        1. MikeSmith | Jun 23, 2009 03:22pm | #13

          if  you  use  a  Trex  sleeve...  they  are  a  larger  dimension  than  other  sleeves

          inside  they  have  ribs...  you  can  cut  the  ribs  out  with  a  12"  sawzall  and  the  sleeve  will  drop  over  the  rubber  flashingMike Hussein Smith Rhode Island : Design / Build / Repair / Restore

        2. Piffin | Jun 23, 2009 05:40pm | #15

          If that composite sleave sstem is Weatherbest, they have a hardware item for mounting on top the deck so as to be strong enough to meet code. That gets you no roof penetration and chance for leak. 

           

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

  5. woodhak | Jun 23, 2009 10:08pm | #18

    Flashing a wood post thru a flat roof membrane is a very tough problem. Even well done over time the wood grows, shrinks and moves horizontaly when the railing is pushed. Then no matter what the wood post can take on moisture and bypass the membrane?

    in order to use the roof deck a new walking surface will be needed? could the railing post be tied into that structurally and avoid penetration of the waterproofing? Or could a steel post be used? Then a standard roofing boot could flash the steel and a wood cladding could hide the steel?

    1. Taylorsdad | Jun 24, 2009 03:13am | #21

      Its interesting that you brought that up as that thought (less the pipes and roof boot) just popped into my mind about an hour ago when I was thinking about walking surfaces.

      1. Snort | Jun 24, 2009 03:38am | #22

        I had to replace a similar railing this winter. I never got to see the original, contractor had removed it, but what was left were copper flashed stumps 4 x 4 and about 1 1/2" high.We simply goobered the stumps with an OSI butyl, an slid a cypress base that housed a cedar 4x4 post over it. A new roof porch on the same house had an epdm membrane with trex 4x4 stumps bolted thru the roof deck, then counter-flashed with epdm. Epdm was covered with concrete pavers, so no uv rays were getting thru.http://www.tvwsolar.com

        Now I wish I could give Brother Bill his great thrill

        I would set him in chains at the top of the hill

        Then send out for some pillars and Cecil B. DeMille

        He could die happily ever after"

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