A welded door frame assembly including a hinge jamb joined to a lock jamb via a frame head jamb, all of which are joined with existing studs and an existing wall. The hinge jamb has a bottom end and a top end and includes a door side base, a door contact flange, and a non-door side trim attachment track including one or more fastener holes. A hinge jamb trim piece includes a connector portion configured to be removably retained within the non-door side trim attachment track and is adapted to cover the non-door side trim attachment track, any fastener holes, and any fasteners. Both the lock jamb and frame head jamb include a door side base, a door contact flange, and a connection flange including one or more fastener holes. A lock jamb or frame head jamb trim piece covers the connection flange, any fastener holes, and any fasteners.