Roof deck over synthetic membrane: water intrusion?
Oops, so I posted this in Outdoors before I found Home. Double posting is irritating but it's kind of relevant to both... I'm new to the forums here (long time reader, infrequent poster), if I just committed a major faux pas, gimme a heads up and I'll take one of these down!
Anyway, so the back door of my 3rd floor apartment opens on to what amounts to a raised back yard; the only problem is that this "back yard" is the roof of a 2 story addition to the brownstone I live in, and I'd rather not put my foot through a very expensive roof.
I've been looking into decking, and right now my plan is a contact-only solid frame all the way around the perimeter of the roof, with a lip extending over the edge of the roof (to supply stability without puncturing the membrane) connecting to the actual frame of the deck which would of course be placed over the top of the brick walls of the building.
From there I was going to face the deck with synthetics, probably with struts placed along the horizontal struts of the roof connected to both the upper deck and sub-deck cross bracing
(depending on what materials I use/can afford and their relative strength).
My hope is to find a way to make the deck in modular pieces that can be removed for when the roof inevitably needs to be resurfaced. So basically it would be large squares (or irregular shapes, whatever) that would sit on top of the struts/cross bracing with the help of a few screws and provide the deck surface.
What I'm worried about is water intrusion at the contact points, such as around the edge of the roof and on top of the studs in the middle of the roof. I know synthetics are much more resistant to this type of failure than older materials, but are they impervious? Where do the pros put contacts so water doesn't leak into the floor below? Even if you minimalize it, the deck will have to come into contact with the roof at some point, or you've found some fancy new way of building I'd love to hear about.
A few other thoughts are footprint: the building is an 1890 Richmond row house, could this be done with a small enough profile to increase the value of the property without damaging the "drive by" value? (I was picturing an iron railing to keep the project semi period, and this roof actually connects to the big hulking wooden fire escape, so it wouldn't be marring a virgin landscape)
Also, do you think any building codes in the country would allow L bracing and big old bolts to hold the structure of the deck together instead of end-nailing the boards? It would make removal for roof work a lot easier. For the corners, would it be better to miter the ends at 45 and run a bolt through the two of them, end nail an L joint or use a thick metal l bracket and a few bolts to hold the joint together?
That was kind of an intense post, I'm just looking to shoot the breeze a little bit with anyone who has any thoughts. Everybody always has their perfect way of doing things, on such a big, high pressure job (if this goes south I'd be poor AND homeless!) I want to really chew on the idea a little bit first. Thanks to anyone who actually read this far!