when you consider the roof pads as protection for
tradesmen access to rooftop equipment, the pad designs can be numerous and economical…
but, now you talking people, parties, furniture, liability. This means railings, safety codes, etc.
Assuming the roof load engineering is sufficient for it’s new intended use…recreational, and the added weight of the deck system, might change it’s structural correctiveness (nice word huh?)
So, let’s say the rafters are ok…that being large enough to carry a party and a deck, then you need a deck/ railing system compliant to local and national building codes. That being said…I would consider a system that would include sleepers for a decking design that would allow for easy access to the roof underneath, as well as an area that would allow for adequately installed and waterproofed railing design/ to code. Look at it as two jobs…
- a roof replacement system with sleepers integrated
into it and
- a roof top/ railing design with the sleeper system.
Considering contractor liability issues for faulty roof/deck designs, it is not an area where one would skimp on costs.
hope this helps