Help!

[Johnstonr]

Hi,

I have recently rendered a 1st floor flat. The back door opens on to a fire escape and above the back door was very damaged by water coming in from some where. 


On first look the issue seemed to be it needed to be rendered which has now been done correctly. 

Last night, a month later it has rained and is extremely windy. And it now has water back in the one corner. 

The only thing I can think of as it's already been determined that it is not above neighbours nor drains or guttering. But the fire escape steps rsj's are built in to the wall via pockets and one of them is about 1metre directly above it. Could this be allowing water in as the steps are corroded badly and I'm thinking in the wind they have a lot of movement plus rain coming in in all directions could allow water in? 

Please help as I am stumped