Hey Pie, when I spec a roof to be used as a garden, I always spec it FA. LOL most guys will throw down MA or actually most guys throw down a 10 year mod bit. I never know when the garden will be installed, when it will be removed, or what areas will exactly be used as a garden. All be it, I've also never done a roof of substantial size to be covered by garden or deck. Primarily I do this because I want a 20 year specification and to the best of my knowledge you can't get that with ballasted (I could be wrong on that) and anyone who installs a very expensive deck or garden on a very cheap roof is a very big idiot. Penny wise, dollar foolish.
The one I recently speced is a 20 square + walls, 16 story, the pedastol paver system will be installed by others and will only cover half the total area. I figured, Tear off, 1.5" ISO, 1/2" densdeck, FA 60 mil PVC. SOLD! We were supposed to start last week but got delayed by some masonry permits because a door is being moved. We'll probably demo the existing deck this week or next if we have a few slow days.
What's there now? 5 layers of BUR and modified.
Speced another one last week, similiar story but 5-10 year old building. The roof installed is 45 mil FA epdm over MA ISO. Bad slope, doors too low, and punctures from the fasteners beneath the membrane. The solution? Tear out doors and raise them up, properly flash thresholds and isntall new doors. Tapered ISO, and 1/2" densdeck set in dash adhesive, and FA 60 mil EPDM. New deck by others. 5 squares plus walls, 5 stories, $16,000. They said it's alot of money. I said I can save them $5,000 but they would be right back in the same situation they are in now. To be honest I even forgot to include the densdeck in the bid so I should be about $1,000 higher, but I always include a ltitle for negotiation, errors and omissions. No problem if I get the job, I just can't negotiate if they ask for a discount.
Property manager wanted me to slope it away from the doors. I showed that the doors are actually below the roof, which is why it puddles the original roofers crushed the insulation at the door so it would be basically level with and not above the door. The only solution is to not taper which would likely make the whole roof a pond, or to move up the doors. Not my fault they built it wrong in the first place. LOL he was expecting a $200 price tag.