ziggy wrote:Is the extra roll of rubberized roofing material necessary/helpful? Any other insight on building a deck/garden?
i researched for literally what seems like hundreds of hours before building (similar situation, 3rd floor w/ penthouse on roof/roof rights). as far as if the rubber material is necessary... i would rank it to be very important cushion; if your supports have any flex to them ever, they're going to wear on whatever material is below, and i wouldn't want that to be my primary roofing material. also from a legal point of view, the condo association itself likely owns the actual roof material and is responsible for its maintenance, so I wouldn't want to be blamed for causing premature wear or anything. i've seen it done both ways, and talked to construction people who have done both. it seems that most people these days are putting the extra layer of rubber there. it seems like it's only the older roof decks i've seen that don't do it. most people don't put the rubber down the full way though, just under each support. in the end, i'd say it's worth it. i think at some point i realized the second roll could be returned and would be able to get all the supports done for the 950sf deck w/ just one roll (kinda went minimalist on how i cut the rubber for the supports), so it was only a $50 or so expense.
the foam i mentioned was a pourable dense polyurethane type thing (almost the kind of stuff they use in floating decks on water). this in the end ranked to be a very expensive option though it probably would've saved a lot of my own labor spent scribing, leveling, and shimming the supports.
figuring out your deck supports is probably by far the most complicated planning portion of building it though. your supports should be primarily perpendicular to the roof joists underneath. in most standard 3 flat sized chicago lots, the joists would run the shortest distance from wall to wall (14' wide or whatever width your building is). if you run the deck supports parallel to the roof joists, you're basically putting a line of pressure directly between roof joists on your roof sheathing. alternatively if you use a stud-finder you may be able to detect where the roof joists are and place your deck supports directly above those parallel to them, but this might be a lot of extra work. it's slightly hard to tell, and they could be perfectly correct, but in tyrus' pictures above it looks like the supports for the planters may actually be parallel along with the roof joists.
with your joists themselves you can do one of a few things... you can get 2x6s and scribe them to the roof for a perfectly level and very solid frame. this is probably the most expensive choice but most solid, but also drainage becomes an issue because there's no gap for the water to move so you have to figure out a way to channel the water. another options is you can get 2x4s, and shim them level. your joists have to be slightly closer together because they hold a bit less weight, or you have to shim pretty frequently. this is what i did, as it was the cheapest way to go and also seemed best for drainage. i had a hard time keeping them in place and keeping everything level while building though, i think i ended up adding about twice as many shims (which really were ~1-2' cuts of wood scribed to the roof line, not small shims) as i expected. you could also get just 2x4s and lay them flat across your roof and not worry about levelness too much. this is by far the cheapest and quickest way, and in most new construction the roofs are flat enough that you can do most of the roof without much pitch problem. but you then have drainage issues as well, since there's no gap underneath for the water to drain (which then can cause mosquito issues, rotting, and all kinds of fun stuff). i think a lot of people who do this method also don't go to the very edge of their roof because the edge has the most curve, though the edge is also a great place to plan for planters anyway. beware of the drainage though, i have a friend that does almost nothing but goes in to replace people's roof decks and he says poor drainage is probably the biggest problem he sees with them of why they're failing. one thing you could do to aid drainage if you were doing the last method would be put breaks in the 2x4s for the water to flow.
btw for the decking itself, i went with western red cedar bought through builddirect.com. they drop ship from the mill in oregon directly, and it was about the same price as getting the cheapest treated wood from any of the lumber yards i called. they have an order minimum, but for a full roof deck w/ 10' boards, their 1 palette minimum was pretty much exactly the right amount (came to $2050 at the time, shipped). i used an electric deer hoist to get it to the roof. it was about $90 at cabella's and at ~40' lift height it is the perfect height needed for a chicago 3flat, best $90 ever spent (then i just sold it on ebay anyway). there's a video in link below if curious of the contraption i used. neighbors might think you're a bit off your rocker, but it saved a ton of time. one contractor i talked to said the labor to bring the wood to the roof was as much as building the deck. having the lumber yard boom it to the roof isn't really an option for a variety of reasons.
http://www.flickr.com/photos/danebrian/ ... 113591323/ are my photos of the start/finish, though the ending isn't that exciting since i cut most of the fun stuff i had planned out. and for some odd reason we never really took pictures of the entire finished deck on the same day, or for that matter when the debris was cleaned up