My house has an attached flat roof garage whose roll roofing had deteriorated and recently had a new Firestone SBS roof installed. Prior to the new roof going in I had ripped off the rotted wood railing which went around the roof’s perimeter. I am now considering installing a vinyl rail system but am faced with the problem of attaching the posts. The posts come with an optional “concrete surface installaton” kit where a pipe with a flange on one end can be mounted directly to the deck and the 4×4 post slips right over it. If I just use silicone below the flange and over the bolts would that be an adequate installation, or will I eventually get water?
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Several ways of doing this, best talk to your roofer for a definative answer.
Eric
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I have a sub that does all of my vinyl railing installation. Usually down here on the island, they are installed over fiberglass decks, often on roof decks with finished space below. He uses a stainless steel post he attaches directly to the decking with four stainless bolts. He dabs the bottom of the flange plate with silicone, puts a dab of silicone under the flat washer, and then puts a dollop of silicone over the bolt head when done. I have never had a call back from any of his work.
Hope that helps.
Brian....Bayview Renovation
This is all very iffy.
I am not familiar with the Firestone SBS, but the first tihing you need to do is find out if silicone is compatable with that amterial.
I have poor luck with any silicone in such applications. It breaks bond with metals and many other products after five years or so. The other problem is whether it would cause the roof product to deteriorate.
Another whiole set of considerations. - the need for a railing implies that people will walk on this roof, raising the question of whether this roof product is designedf or that kind of use. Most roof membranes are not and need another kind of surface applied.
Then - it may be too late for this, but any railing needs to be able to withstand 250# of horizontal thrust. That usually means that the fasteners for mounting the post need to hook into something far more substantial than just the sheathing plywood, so you have to plan ahead and mount blocking in the framing under the sheathing before the roof goes on. After the roof, another question comes up - most modern membrane roofs are installed over a proprietary base material of some sort that is often an insulator type product similar to homasote. This is not as dense in compression as plywood, so adding posts that can act as a lever, will let the fasteners create some flex there over time, and continued alternating pressures. The kind of fastener seal you suggest is know as a self florming compression gasket. It works fairly well under constant even pressure or torgue. But on a raining where the forces on it will regularly change with weather and the people leaning on it or not, the effects of this gasketing will eventually loosen or break baond and lose seal.
Have you got a link to the Firestone product and the way they suggest attachments for various uses and conditions?
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