We live in a leasehold (nearest US equivalent: condo) flat (apartment) at the top of a seven-storey building. Only our floor has real balconies, and the floor of each balcony is effectively the roof of part of the flat below. It's very solidly sealed/tanked. We have two such balconies, each on a corner of the building. Each has two downpipes from the gutters around the roof, and each downpipe feeds into an open drain. One of these drains is at the top of a slightly incline in the surface, and mostly only drains the gutters. The other is at the bottom of a slightly incline, and (in theory) drains the balcony as a whole, as well as another downpipe from the gutter.
On both of the balconies, the latter drain has a plastic cover about 1cm thick, which looks like it was designed for a slightly bigger drain (the openings represent a bigger space than the drain does), but it works. On one, it is loose, but doesn't end up moving around, so this is fine. On the other, it has been stuck down.
All the way around.
With sealant of some sort, I think. At least, we think we can feel something around the bottom of it. There's no evidence of any sort of screw or fitting, and the two drain covers look identical.
So on the balcony with the loose cover, the water running off the balcony itself can actually get 'under' it (not too efficiently, but it works), while on the balcony in which it is stuck down, the water only drains if it's over ~1cm deep. Then stops, unless we brush it so it is locally deep enough to go over that edge.
Is there any way we can safely, without damaging the weather-proof surface (which generally has decking tiles over it), un-stick that drain cover?
