Cracks in block wall

[m0t]

Two of my downstairs walls have developed cracks from the tops of the door frames rising vertically up to the ceiling and getting wider at the top.

Both walls are built from 1930s concrete blocks (which are soft as anything) and are not structural and single story. It looks like the blocks are built off the door frames.

The cracks originally opened last winter (although evidence that they had been there for some time) but then closed around may and have just reopened again.

When the cracks open the doors get stuck.

Any ideas what's causing this and how to fix it??

 

[theprinceofdarkness]

Subsidence or more likely heave? The clay ground gets more water in it in winter, so expands and tries to bend your house.
Frank

 

[m0t]

I just lifted a floorboard to see if there was any cracking at the base of the wall, but there is no base of the wall.

The block work is built on top of the wooden floor (which is straight)

 

[^woody^]

Subsidence or more likely heave?

That's the least likely for cracks in that location.

Thermal cracking is most likely due to winter heating patterns and seasonal humidity changes. Having no lintels does not help.

Plaster repair with mesh across the crack, as there will most likely be seasonal movement from now on.