Crack to external wall

Hi. Spotted this crack to one of the external walls of an outbuilding that we’d had build a couple years back.

We had an issue with one of the walls last year which is a single wall. For that the builder put in an expansion joint.

Now I’ve spotted a crack of one of the double walls, I assume the builder means breeze block built hence double wall.

Now I’m wondering whether this crack looks like more settlement issues or simply render crack to patch up. The crack runs top to bottom. Slightly more bigger than hairline but not much more, at least at this stage.

underpinning seems to be an answer to settlement but I’m worried that this would be massively costly and the builder will simply refuse to do at his expense. My kids use the building so need it to be safe at the same time!

thanks

Looks like minor movement, wall may need expansion joint .

Thanks foxhole. I’ve been monitoring it over the last month and now has grown to this.

Do you think it’s worth monitoring yet further to see if continues to widen or simply go for the expansion joint now? Not sure what is the point of no return! Thanks