Damp in Wall? Wheres it coming from?

[round01]

Evening all,

Need some opinions and solutions pleeeaase!

Brother in law owns a block of flats and asked me to update/decorate one of the flats before a new tennat moves in. I noticed some of the plaster on the lounge wall was blown so advised i would hack off and fill/repair etc...

Started to pull off the plaster today and the whole wall started crumbling back to the external wall!! Felt damp and black stains on the block work. My imediate thoughts were...leak from flat above?? Water coming in through external wall?? Then i took a look outside and noticed the end ridge of the roof and the black water stains...my gut feeling is the water is coming in and traveling down through here (see pics)

Just need someone elses opinion and possible solutions??

Thanks

 

[HERTS P&D]

I would be guessing the roof.

Andy

 

[foxhole]

Roof looks iffy , loose tiles etc. Verge tiles look to have bee replaced but looks a poor job.

 

[round01]

Thanks gents.

Im pretty sure its the roof/ridge.
Best way to deal with it? After getting roof fixed obviously!

Hack off the internal wall, re render and plaster?

Stud wall with insulation?

Thanks

 

[Odds]

Loose tiles, to be sure, although i'm surprised he hasn't been inspired to the solution with all those Dreamcatchers in t'window.