I want to build some decking onto a new re-layed pitch flat roof, My plan was to consruct a 2x2 framing and then secure decking onto this, size would be 12ft width, 5ft long, My worry is would the weight of this be too much, when roof relayed ensured extra thick board was layed,and joist underneath were in good order, any suggestions how to protect framing from damaging roofing felt, also how will water still run away ok etc, any suggestion would be appreciated - thanks