We hear you, this one does sound a bit strange to the uninitiated! Let us explain.
Structural beams are often placed on a solid brick or structural grade timber offcut. Why? This ‘packer’ ensures the structural beam doesn’t interfere with the ceiling joints below.
It must be a non-compressible material to allow the structural beam load to be transferred to the loadbearing wall below. The beam is also held in place by multiple lateral roof members (hangers) to ensure lateral movement isn’t possible.