Ponding issue on a fibreglass balcony floor

Sounds like the roof has been done wrong to start with. There should be a slight fall toward the drain area, so ponding should never occur. The only way now is to build up the area leading to the ponding spot. This can be done by adhearing a thin layer of ply, and building up layers of fibreglass to the required hieght, to create the desired fall.

I have never heard of anything so crazy as adding a thin layer of plywood to make up the depth of the area ponding. Plywood should not even be used in conjunction with fibreglass! Two options: 1: Cut out the drainage and grind off the fibreglass around this. Router the drainage outlet deeper than the lip of the area ponding and then re-fibreglass the entire deck with two layers of 450mm csm (once remainder of the deck is prepared. 2: Mark out the area of ponding and mix on a ratio 50/50 resin and fillite with 2% catalyst. Allow to cure then sand down removing any high spots. Then re-glass the deck as per the above. To be honest you can still be chasing your tail around the deck and never truley get rid of a badly ponding area. If it is minor and not deep and drains within 24 hours then you could tile the area with rubber deck tiles which mask the issue and allow the area to drain. KR Drew

This can be a straight forward fix as is just the need of grinding off the pond area and get some 9mm osb board on this section and then just re fibre with faded skill and it will look perfect again

The answer to the problem is if the water is just lodging around the dropper or gully then the gully was not sunk or rebated into the plywood before the started the fibre glass which means they cut the opening for the gully and just placed it on top of the ply... (I'm presuming the cut ferrings and falled the rain water to the gully)this creates a ridge and will create a puddle and any roofer worth his money would know this