J

Jack Rafter

A short roof rafter, usually spanning from the eaves to a hip or from a valley to the ridge.

Jamb

The vertical side of a door or window frame.

Joinery

The wooden finishing components of a building such as skirting boards and architraves internally or fascia and soffit boards externally.

Joist

A steel or timber beam supporting a floor or ceiling lining.

Junction box

A box that hides electrical connections.