Damp at top of window cavity - suggestions

[Ramekin]

I have damp at the top of a cavity that a window is recessed into. I'm probably going to end up getting a ladder up and having a look on the outside and would like some ideas as to what to look for.

The window is UPC and (I think) relatively new. The house is 1960s. A little way above each window opening in the house there are three or four slots, one brick high, cut into the mortar. I guess these are due to some kind of cavity insulation foam being put in.

There are five windows on the face of the house in question (which is exposed) but this window is the only one with problems.

I would be grateful for some hints of what to look for. Thanks.

 

[JohnD]

the slots sound more likely from putlog scaffolding, in which case they could reasonably be mortared in now.

 

[Ramekin]

Ah, I wonder then if water might be getting in that way. Never having used scaffolding I hadn't heard of this. Thanks.

 

[JohnD]

they might also be weep vents intended to let water out of the cavity, but I ask myself, how did it get in?

 

[Ramekin]

I'm learning new things here. Weep vent might be more likely as I see from the internet that they sit above lintels. Checking for blockage seems like a plan.