Hi All, 

My Current 4th floor space is open to Sky and I have decided to build a Roof over the open area to maximise the use of the space. I know its not legal, but thats a risk I have to bear. 

In terms of material of the roof I was given either Aluminium Composite or Polycarbonate panel. Price is the same. 

Was recommended to use Aluminium as was told maintenance is easier and feels comfortable during daytime (without sun impact).  But aesthetic wise much prefer the polycarbonate see thru look. 

Was wondering if anyone here done something similar and can share the experience 

Most polycarbonate is see through so you get the light and also the heat. Aluminum composite panels would have some form of insulation built in so you cut down the heat as well.

for long term maintenance wise, composite panel would be better rather than polycarbonate. With polycarbonate panels, if the end cap come loose, you are going to get water ingress inside the panels. That's what happened with my in-laws car-porch roof

which panel to use will really be your planned usage. if you are planning to use the area very often during the day, then choose composite panels since you won't feel the heat. If the main purpose is just to have extra area and not going to be used that often in the day, then do polycarbonate.