Jack Beam

A beam used to support another beam, rafter or truss and eliminate a column support.

Jack Truss

A truss used to support another beam, rafter or truss and eliminate a column support.

Jamb

The vertical framing members located at the sides of an opening.

Jib Crane

A cantilevered or suspended beam with hoist and trolley. This lifting device may pick up loads in all or part of a circle around the column to which it is attached.

Jig

A device used to hold pieces of material in a certain position during fabrication.

Joist

Light beam for supporting a floor or roof.