building decking onto existing flat roof

[philly23]

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

 

[noseall]

if you wanted a balcony roof then you would have been better off with an asphalt type surface.

i cannot see your scenario working.

 

[^woody^]

I can't see a problem as long as the roof has adequate drainage.

Decking places little load on the felt

 

[noseall]

the roof covering will be vulnerable in the summer and vulnerable in the winter.

the deck supports will be vulnerable to the rain.

 

[^woody^]

This will be exactly the same as when promenade tiles (and spacers) are laid onto flat roofs

The 2x2 bearer will just sit on the felt with no problems

The only other concern to drainage, is to make sure that the timbers are not so long as they touch the perimeter angle filler or upstand - so as not the gouge the felt at the upstand angle

Theoretically, the decking will provide more protection to the felt from damaging rapid temperature changes or shade/sun stresses, and so could increase its life

The other issue is a b/regs one of external fire spread. This may not apply if this is maintenance, but if this decking is close to a boundary (less than 1m) when b/regs would otherwise require specific fire precautions, then it would be wise to consider the implications.

 

[noseall]

well i think it's doomed, DOOMED!

 

[big-all]

what size are the joists!!!
what is the unsupported span!!!!

 

[Thermo]

weve done these before and the frame has sat on the slabs woody referred to. No problem with teh drainage as the frame is off of the roof.