Support for ceiling finish where ceiling joists run parallel to a partition

Source : Canada Mortgage and Housing Corporation (CMHC)

Ceiling joists are similar to floor joists in that they carry the weight of the room above them, but differ in the thickness and material used for their design. For example, I-joists are more commonly used than single-ply blocking due to their versatility and strength. A ceiling is also used as a handrail in addition to providing stiffness to the subfloor.