What is causing damp lines and plaster cracking near ceiling?

[Torpisf1]

Hi All,

I'm looking for some opinions on what could be causing the issues shown below. The outside shot shows the rough location of the internal shot (it's probably slightly further to the left in reality - possibly where the water marks are on the brick work... could that be the cause? and if so how do I stop it?!).

The damp patches have occured over around 3 years, so its very slow ingress. Could it be condensation in the roof, or is it more likely to be a very slow leak?

The water marks run along the straight line shown in the picture - there are also random blobs (around 1-2cm) in other horizontal straight lines across the ceiling (not pictured).

You can see the plaster has also popped on the wall.

Thanks

 

[oldbutnotdead]

I'd be looking at that gutter- appears that water coming down the valley is under or overshooting it causing that staining and very likely your damp/cracking problem. Or the end cap may not be sealing properly or the downpipe is blocked and gutter is overtopping.
Whichever, ladder time to start with.
EDIT Closer look- it may be the valley has failed allowing water to get behind the soffit. The valley appears to be covered with Flashband or similar which is not a good sign.
Still ladder time to have a shufti

 

[tell80]

Well spotted oldbutnotdead.

 

[Alastairreid]

The lead saddle at the top of the valley has lifted as well.

 

[oldbutnotdead]

The lead saddle at the top of the valley has lifted as well.

Good spot-lifted? Looks like it's been half peeled off.....

 

[Torpisf1]

Good spot-lifted? Looks like it's been half peeled off.....

That's the flashband flapping about (the "repair" was done before we moved in)... I'll get a roofer up to have a look I think - looks like it's probably going to be new valleys!