The house was built in 1978. During an exceptionally severe thunderstorm last week, it became apparent that water was leaking through the balcony and seeping through the ceiling into the room below. After inspection by two craftsmen, there are now two different pieces of advice on how to proceed.
First opinion: seal the open space with silicone or something waterproof and put a metal sheet over it.
The 2nd opinion: replace the entire window because it is too high and protrudes too deeply into the floor -> install shorter windows and replace the balcony covering and possibly install additional drainage in front of the window.
Since both opinions differ considerably in cost, we, as "home amateurs" are naturally unsure of which would be the right one. It should also be said that the problem only occurs during heavy downpours, since during normal rainfall the balcony is very well protected by the roof.