Render repair above window

[blammo]

Hi all, I need to repair this bit of render above my window, should I pack it with something before applying the render?

 

[Wayners]

External Stainless Steel Expanded Metal Lath.
Fix on before rendering.

Not my area of knowledge but what I would use. I have used myself

 

[ree]

OP,
You need to determine why this defect has occurred?
It looks like water penetration has got behind the angle beads?
Any signs of internal damage?
The galvanised metal angle bead is exposed and rusting - it needs to be exposed to the extent of the rust, and then, at least, have the rusted portion sawn out, & replaced with plastic angle bead.

Best practice would be: Given the RH reveal also looks to be water penetrated then it might be best to replace all the angle beads, and both rendered reveals & window head render back to masonry - & then done again
with plastic angle beads & two 10mm coats of render.
Is there a steel lintel above the frame - is it in good condition?

 

[Alastairreid]

Looks like a reinforced concrete lintel and the rebar has rusted blowing the concrete.