Knitted fire barrier fabrics for use in forming a flame retardant article having a core include, for example, a plurality of flame-retardant yarns formed non-uniformly around a circumference of a knitting textile cylinder in a knitting process so as to define the knitted fire barrier fabric having at least one differential zone of material in a longitudinal direction of the knitting textile cylinder, and wherein the knitted fire barrier fabric being disposable on the core so that the at least one differential zone of material of the knitted fire barrier fabric providing a differential protective capacity to at least one selected portion of the flame retardant article.