Vertical crack - are helifix bars sufficient?

I'm currently renovating and I've found a rather large crack where the front of the house meets the back - I assume they were built at slightly different times.
Do you think I can get away with just using helifix bars or something similar with resin to tie the walls together?
Thanks in advance.

Dan

"Get away with" is that the same as "bodge"?

It depends what caused it, or is causing it.

"Get away with" as in will be sufficient rather than re-building the entire rear of the property... I'd view a bodge as just plastering over it...

The surveyor made the following comments

"Internally, to the front section of the party wall within the front cupboard of the back addition half landing there is vertical cracking which indicates that there has been settlement between the back addition and main building. The main building is built in 337.5mm (1.5 bricks) up to first floor level therefore is a more substantial building than the back addition structure that is built in 225mm solid brickwork. This cracking is indicative of inadequate bonding between the structures and that the back addition has settled slightly away from the main building. However there is no evidence of any recent cracking or movement to the party parapet wall above and no corresponding cracking to the front left hand side flank elevation of the back addition where it meets the main building, nor any other significant cracking to the external elevations of the back addition therefore it is reasonable to assume that further significant movement is unlikely under normal circumstances bearing in mind the age of the house."

If no further movement is likely, then you can just gob it up with mortar, mesh over the front and then plaster away.

If movement is likely then helibars may be the answer but it depends on whether potential movement is up and down or sideways - but in this scenario you would have to deal with the cause of movement and not just the crack.

But in context of a major refurb, you may think it worthwhile to install some helibars for good measure. But the issue is whats on the other side of that wall? The surveyor says its not cracked, but a proper job would need bars inserted from both sides and every 225-300mm up the wall, and not just on the inside face.

was the surveyor a SE - or a mortgage surveyor?

did the surveyor see the plaster removed and the partition demolished like we can see in your pics?
the surveyor seems to be saying that there's been Differential Settlement, and that settlement has caused the "inadequate bonding" to crack?

whats happening above the crack following a vertical line to the roof area eg. hump in the plaster ?
and similar, whats happening following the crack line down to the foundation?
have you had a level on the floors both sides of the crack?

outside is there any rendering or cladding?
have you been up behind the parapet and had a look?

is there a cellar in the main house?
are the studs and piece of skirting supporting anything?