Roof/wall edge water marks

[Bartholomew]

Good morning y’all ! 
I’m trying to sort out this water/dirt  marks. So I’m looking for solution what is going to be the best way to fix it. Was thinking of filling up the gaps between this blocks and then lying sort of rubber or fix metal capping with dripping verge on the top of this blocks. House needs a full paint but I’m not gonna do it before I sort it out.  Can anyone please recommend how to approach it? Bartholomew 

[markc]

I’m guessing there is/was a chimney close to that gable and the bulk of the dirt is soot falling and being washed down.

A good clean down of the cappings will get rid of most of the problem if the chimney is no longer there or being used.

 

[tonyshouse]

Just rainwater running off the edge of the parapet coping , I always tilt them towards the roof to avoid this problem. Or better remove the whole parapet, they let in damp, wet and cold. 

[Bartholomew]

5 hours ago, tonyshouse said:

Just rainwater running off the edge of the parapet coping , I always tilt them towards the roof to avoid this problem. Or better remove the whole parapet, they let in damp, wet and cold. 

Yeah , that’s right rainwater is causing this marks. And also gaps between capping partly gone due to movement. What I’m thinking of is redoing that gaps and lay down a metal capping on the top of existing. You think using frost/water  proof glue like tiles glue will do the job?  

[tonyshouse]

Metal caping is a good idea, ensure all water drips and flows towards the tiled roof. It also should protect what is there and any defects won’t get worse.