Damp patches on inside of gable (?) wall

Eldi_Dos

The airbrick above the window with frosted glass appears to have expanded foam poking through, do you have any info on why it is there?

Ben1989

Yes I'm more than happy to investigate which I will this weekend. There's also areas where the small stained glass window is. We get a lot of condensation on this window.

Eldi, yes. This vent was filled in inside and so put foam on the outside to insulate it.

Ben1989

I'm wondering what the solution is if I were to find cracks?

Eldi_Dos

Assuming your gutters and downpipes are all clear and in good order I would think water has been getting through cracks in render for some time but this had not been noticed as artex was hiding it and the airbrick was venting space around window. Now artex is off and airbrick is blocked any moisture is being drawn through wall, especially if you have a decent radiator in that area. 
I would clear airbrick at least until you have resolved this issue, there will be other posters on here who will give you good advice on how to repair render.
It might not seem it at the moment but removing the artex has let you sort out problem rather than it being hidden and getting worse.

stuart45

Ben1989 said:

I'm wondering what the solution is if I were to find cracks?

Quick fix is with the mastic gun. 

twopenny

You really need to wait and see if it's damp behind the crack. 
And it should be throughly dry out before you fill the crack or your sealing moisture in and its only exit is your new plaster.

stuart45

The problem with cement render is that it won't  dry out through the cracks, as it gets into the brickwork and behind any blown bits. It's best to stop more coming into the wall.

Ben1989

What's the best fix then? Any particular sealant? Just paint over it?

stuart45

Any exterior one will do, unless you want to get some Toupret Touprelith F which is good stuff.

Ben1989

Here are some more marks that have appeared. Who or where would you go to have this addressed?