Hi Sifu,
I am in the midst of contemplating changing my 20 years old roof.
It is aging, and certain parts looks like peeling OFF.
The roof was built for my extended kitchen.
The contractor suggested tiles with plate ( I think it is zinc below the tiles )
I have written on separate thread on this. But today I notice this discussion here.
Firstly, can anyone tell me my existine roof, is it ASBESTOS material? I am noob and not much knowledge on this. Hope sifus and other owners can provide some light.
End last year I noticed two holes on top. I managed to patch the holes. I suspect, due to some fireworks that drop on the roof that created the holes.
The current slop gradient is very much less than 30 degree.
I think this roof can still stand couple of years more; but if it is asbestos material, then I will be prompted and trigerred to change asap.

That is also my gut feeling - asbestos
So, I will arrange to change out pretty soon.