Filling corner of dot and dab wall

[gpk]

I was about to redecorate a room but it had a crack down one of the corners. I was going to do a simple fill but on closer inspection it had already been filled with some flexible type of material, possibly caulk. This itself was cracked so I just started to pull it out. It mostly pulled out in one piece and has left me with a 2-3mm gap between the plastboard in the corner.

There's about an inch gap through the gap to the blockwork behind. What's the best way to finish this gap now? I was thinking of filling it up with foam to provide a backing, then filling as normal, but not sure if there is a better way.

 

[motorbiking]

You could foam it to reduce the flex, but you are going to need to tape and skim as well

 

[gpk]

I wonder if I should tape over the top of what's left of the existing plaster, or should I take back some more? Is the paper tape the best or sticky fibre glass mesh?

 

[Deleted member 292770]

plasterers scrim tape.

 

[Wayners]

I'd foam.
Dampen down with garden sprayers in the joint and foam all the way down. Don't overdo it and use low expanding board foam. Just fill enough and keep tidy.
Cut off overspill when dry then tape and smooth. Mesh and toupret powder. Don't bother with corner tape just run down two strips of mesh tight to corner either side.
Do one and sand smooth then other side to get straight.

Looks like it had mesh applied but failed because of movement.