Drainage on balcony

Torch on flat roof system first, Then You can get round plastic feet designed too sit under the four corners of the tiles.

Hi, what’s the structure of the balcony? If you’re thinking of laying over existing tiles you don’t want to overload the roof. I would take up the existing tiles see what the condition of the roof underneath and maybe replace. Lay over a protection layer and install adjustable pedestals so you can adjust them to the fall of the roof keeping the tiles level especially through the gutter.

Go for a single ply material such as Renolit Alkorplan with protection layer this will have a longer life than torch on felt then use the plastic feet that adjust up and down for your levels and support tiles which will also bridge your gutter

Hi I would advise against torch on as when this gets hot it goes soft so the feet you use or the composite tiles would sink into it when you stand on them which would cause you problems. I wouldn't block any of the gutter up as it's not very wide to start with. What you can do is lay composite decking tiles over the existing tiles as they are not to heavy and water drains through them also they will span the gap of your gutter. This does depends on your height and levels. If you do need to take the existing tiles off I would advise a grp roof or a rubber roof as these are both hard wearing and composite tiles sit well on both.