repair damage in plastered wall

[yartin]

Hi
I had an issue with 2 walls, pls see pics, I think the initial decoration went wrong. It's been like this for 3 years.
I scrapped all loose parts and more this morning, pls see pics.
Is this what to do next a good plan?
1. Apply PVA 50:50
2. Fill with Tourpet
3. Apply 123 primer
4. Paint

Thanks

 

[Wayners]

You need a plastic corner bead as won't rust. If it's just that spot.
Looks like damp for some reason on that corner pushing plaster off?

 

[Koolpc]

I agree..some moisture there for sure...

 

[yartin]

I can't see any damp after scrapping the loose parts and old filler, it's an external cavity wall, pic attached. There are no pipes in the wall.
It hasn't pushed plaster off, it's my old filler being pushed off. something wrong went there, may be filler was too deep didn't dry fully when I applied paint and hence the reaction is my guess. I remember using heat gun to dry filler, may be didn't help.
.

 

[JohnD]

This picture

View attachment 350449

looks like rainwater entering around the doorframe and making the wall wet.

Observe that the highest point is next to the doorframe. Water descends by gravity.

the fault is probably on the outside, and may be higher than the water damage.

 

[Wayners]

Heat gun? Too hot. Hair dryer is better but just stick to tx110