can someone please tell me whether this crack is serious? we bought this 4 bed room semi a few months ago. originally, it was a 3 bedroom semi, the previous owner (before the vendor we bought from) added a kitchen extension and a double bedroom above garage. I firstly spotted a crack in the kitchen wall (I think it is the joint between the main house and kitchen extension). A structural engineering said it is nothing to worry about, a plaster facial repair will be enough. later on, I noticed the crack in the same area but below the cupboard, which seems the same crack from the top but hidden by the cupboard. In order to have a better view, I cut the back cover open to expose the crack in the below picture. the crack seems extended below the kitchen work top around 10-15cm.