View Full Version : Flat roof railing

05-05-2005, 10:37 AM
Hello all, I'm new here and thought I would post this question. I've been reading the posts and have found a wealth of information.

The kitchen in my house juts out of the back and has a flat roof with a railing around it on top. This roof is leaking due to its age and a shoddy patch job done by the previous owners. The wooden posts for the railings go throuth the roof material as near as I can tell and are a possable cause for the leak. We are having estimates made to put on a new roof using either regular roll or EPDM material. I want to have the railing put back but don't want to use wood. I have been checking out composite and PVC material but haven't found how to attach the posts to the roof. the closest I've come is a metal bracket I found in the bottom of a post made by Veranda that I found in a local HD. It looks like a lag bolt can go through the center of the bracket, through the roof and into a joist. Will this remain watertight? I wanted something the roofers can install then I'll go back and put up the rail. There are a bunch of issues that I'm raising in this rather long post so please, educate me.


05-05-2005, 11:40 AM
what is the size of this roof and what is its use?

05-05-2005, 12:07 PM
It's not very big, about 6'x11'. My wife wants to be able to use it to sit outside with the dog. Now, Why am I fencing in the backyard...? Anyway, it never got used last summer so I don't see it getting used this summer for that purpose either. I'd rather not use it and get the rubber roof put on with a railing to make it look nice and so the inspector doesn't give me a fine for not having one.

05-05-2005, 12:51 PM
Personally we try to never penetrate a roof of any kind ESPECIALLY a flat roof. If you do decide to penetrate the roof, I recommend a "pitch pocket".

Posts that bo through the roof will always leak. I can guarantee that. They crack and funnel water inside, not to mention the wicking action of the wood soaking up water. Your best bet is to remove those railings completely and perhaps installing something with the pitch pocket mentioned above, or some kind of metal railing that can use a few small screws, and install "water block" under the bracket.

05-06-2005, 06:40 AM
could you possibly anchor the railing to the sides of the house where you exit onto the porch? I think on a 6ft depth it would be plenty stable if done well.
Grumpy, whats a "pitch pocket?"

05-08-2005, 10:25 AM
Pitch pocket is a flashing that you mount on the roof and then run a pipe or wire, or in this case railing through the roof. Then you fill the "pocket" with some kind of sealant. They are called pitch pockets because back in the day they were filled with hot tar, which is pitch.


http://www.wynwood.net/Photos/5N-Frame;Roof;%20Shows%20Framing%20and%20Pitch%20Pock et%20of%20Post%20Supporting%20Sundeck%20Railing%20 2.jpg

05-09-2005, 06:48 AM
thanks, Grumpy

05-11-2005, 06:56 AM
The detail I have used is similar to the one already discussed but avoids exposed sealant in a pocket and hides the penetration detail.

Remove about 3/8" deep x 8" high from the surface of a PT 4x4 at the point on the post that will be just above the roof surface; leave an opening for the post in the sheathing, recovery board and EPDM roofing membrane; install the post and bolt it to the roof framing from below; add an uncured neoprene or EPDM membrane boot at the post (similar to the pitch pocket detail) and attach the top of the boot to the post with a metal termination bar and sealant. (It might be wise to protect the membrane from the PT wood although I know of no incompatibility but PT chemicals have changed recently) Cut the post to the correct height and slide a 6x6 pre-fabricated wood post cover over the top ( http://www.woodwayproducts.com ) and add a post cap. Base trim can also be added.

Woodway Products makes great looking pre-fabricated railings systems and lattice panels in cedar and mahogany that are easy to install. Expensive but often worth it.

05-11-2005, 11:30 AM
That diagram shows installation onto a wood deck. I fail to see how this instalation differs at all from the above posted pitch pocket if installed into a flat roof.

Maybe I am missing something visually?

05-12-2005, 04:16 AM
Thanks for everyone who has helped answer my questions.

Grumpy: Do you know if composite deck materials would react negativly to the roof material? I have been thinking about using composite posts rather than wood but will the sealents or pitch or whatever stick to the plastic/wood or PVC material?

Again thanks for the responses


05-12-2005, 09:28 AM
Grumpy, sorry if I wasn't clear.

The detail I described uses a pre-formed synthetic rubber boot to flash the 4x4 PT post into the EPDM roofing membrane and does not use a metal curb or poured sealant filler. The 6x6 wood post sleeve from Woodway Products is simply decorative and only serves to cover up the flashing detail and the PT post. As I said, this is expensive but it is the best looking railing I have ever seen.

The pitch-pocket detail will work fine but I offered an alternative because it serves several purposes which may or may not be of interest to Jeffrey:

waterproofing does not depend on exposed horizontal sealant
the flashing detail and the PT post is hidden
the post and cap in cedar or mahogany look great
the flashing detail is the one recommended by EPDM manufacturers (see below)

Although a pitch-pocket is intended for built-up asphalt roofing, it will certainly work with single-ply membrane roofing as Grumpy can attest. However, EPDM manufacturers only recommended it for multiple penetrations through a single large hole where the recommended pre-formed boot detail cannot work and involves packing the bottom of the metal pocket with hydraulic cement or sand and pouring an inch of EPDM liquid sealer to the top of the pocket. I much prefer the synthetic rubber boot but it might not work for Jeffrey since he wants to put up the railing after the roofers are finished, although that seems to me to be an unnecesary requirement that greatly limits his choices.

The old tar pitch-pocket was a good detail because the tar was aggressively sticky and self-repairing in warm weather. It is unfortunate that there is no modern equivalent.

Regarding sealant sticking to a post, the manufacturer recommended method is to wrap it with EPDM Tape Primer. If you do not use a pourable EPDM sealer you would need to check with the manufacturer of the sealant you intend to use (be sure to select one recommended for exterior horizontal application which is unlikely to be sold at HD.) Any plastic/composite material will probably be more compatible with the sealant than PT wood.
EPDM is known to be incompatible with bituminous (asphalt) products , petroleum oils, solvents, gasoline, and animal fats.

Regarding brackets
I once had a contractor install an EPDM roof before installing the railing posts. We added large galvanized steel brackets lag screwed into the roof with EPDM patches covering them. Fortunately there was not a great distance between corners and the owner rarely uses the roof so it worked fine.

I think that covers it. I just finished a difficult project so I'm in a detailing/specifying frame of mind. Time to get outside.