I need help from a plasterer before i lose my mind

[SENsupportplease]

We have a floor to ceilling crack at the join of an old wall and a new (2018) wall

this has been filled and repaired 3 times and always comes abck

it is totally straight, max 1mm wide

engineer has confirmed brickwork is fine, no structural movement, just thermal movement

i have spoken to 14!!! plasterers and builders, all of whom are offering different solutions. Including to skim (no, tried that), tape (no, tried that) mesh (tried it), and rebar / helibar (the brickwork is fine)

One solution which makes sense but i don't know whether to trust it is to - install a movement bead on the internal brick, then skim over it - this will leave a shadow gap but prevent cracking as it allows movement. And apparently we want to allow the moment.

is this even a thing? please can someone who knows what they are talking about help me!

My DH is a plasterer so I’ve just asked him - he says that if the problem is thermal, then rather than re plastering it, cement the gap and paint over it, as cement won’t be affected by temperature in the same way plaster is

Maybe something like toupret fill flex.

You could get a tube of that for about £10 and try it out.

It's basically filler with a bit of flexibility in it so when stuff moves it flexes with it.

If if doesn't work you're £10 down. If it does you've saved maybe £250 on a plasterer.

Thank you both! Would you take it back to brick before trying these solutions? at which layer would i use the cement / filler?

im going to take a knife to it this weekend and see what is actaully under tehre

@SENsupportpleaseDH says take it back to brick and if there’s a gap in the wall between the joint, dry pack it (a combination of sand and cement powder) and then cement over the top of it - he’s more than happy to jump on a call/FT with you and talk you through it if need be

Thank you, that is very kind! Christmas decorations have taken over but if the offer stands in future I may well accept - depends how overwhelming the DIY meltdown is

@SENsupportpleaseoffer is there as long as you want it! Have a lovely Christmas when it comes