Cracked leaning internal walls into cavity?

Can anyone help me with this problem?

I have 2 bedrooms that have a large vertical crack at the point where their joining wall meets the inner leaf exterior wall (circled in red).

The walls are not plumb and it appears that the inner leaf wall is leaning into the cavity and pulling away from the joining internal wall. The line you see in the wallpaper just under the ceiling, is the point where the wall would have originally stood had it been plumb

The internal load baring wall is brick and the inner leaf is concrete block. The external brick outer leaf wall is showing no signs of leaning or bowing.

The surveyor said it was just 'shrinkage cracks'

Does anyone know what is happening here and how I'd go about fixing the problem?



Thanks

 

Which way does the roof span?
Might be failed connections between the rafters and ceiling joists (assuming the rafters span on to the wall), which enables the rafters to push out the inner skin. If they didn't put many wall ties in at that height, it wouldn't affect the outer skin, at least in the short term.
I doubt it is just 'shrinkage', particularly if the house is older (?)

 

Hi Tony, thanks for replying.

The roof is a twin pitched and hipped with a twin pitched projection at the front (just quoting my survey here, I have no clue) and the house is 1950s ex local authority.

I've circled on the photo where the leaning is happening on the inside between the front and back bedrooms.

If it is a case of failed connections between rafters and ceiling joists, what in your opinion would be the solution?

Thanks again