JustMe wrote:

It's an internal, dividing wall. The single crack area is downstairs
(ground floor), the multiple crack area is upstairs (same side of
same wall, above floor divide).


So the crack effectively goes from floor to roof? (discount the downstairs
doorframe because it only starts above this)

The upstairs area is worse because the wall isn't perfectly flat, but
curved. In installing a false ceiling above the area of the upstairs
wall, a piece of 2x2 batton was screwed VERY tight along the wall.

I'd get this looked at ASAP, simply carrying out cosmetic work is a waste of
money until the underlying cause of the crack has been remedied.


The wood being reasonably straight and the wall being slightly
curved, the wall was pulled a little by the tightly screwed wood,
hence loads of cracks appeared in the loose plaster. Upstairs is a
hack back to brickwork and replaster job, but downstairs is a single
crack that was there when I moved in (before the false ceiling job),
which I carefully scored and filled before and which has reappeared.

That tells you that it's getting worse - normal plaster cracks don't
reappear, the crack *must* be in the brickwork behind.


AFAIK the house isn't moving (survey info, other houses in the
terrace, no other indicators on my house etc all point to the ground
being sound). Exterior brickwork front and back (no sides cos
mid-terrace) is sound.

All exterior brickwork sounds ok, this door downstairs which has the crack
above it and underneath where the upstairs wall has slipped - has everyone
in the block got this door in this position or has someone knocked it
through in the (recent - ish) past? - my money is on the lintel - it's
either rotted away or there isn't one in.