St Joseph High School is set to undergo a major expansion with the construction of a new $421.2 million annexe aimed at easing overcrowding and enhancing the delivery of academic and technical education.

The project officially commenced on Wednesday with a sod-turning ceremony for the two-storey, 22,360-square-foot facility, which is expected to be completed within 10 months.

Once completed, the annexe will accommodate 10 classrooms, physics and biology laboratories, an AutoCAD room, an Allied Arts room, classrooms for clothing and textiles and home management, a counselling room, staff room, sick bay and modern washroom facilities.