A fire barrier for use in dynamic voids to seal against the spread of fire. Flexible foil-backed insulation material is supported by a woven metallic support screen positioned in the void. As the surfaces defining the void undergo relative movement, the ability of the individual wire elements of the screen to move in a scissor-like fashion relative one another allow the screen to distort laterally without shearing, wrinkling, or buckling while the insulation material floating thereon is effectively isolated from any shear forces. The foil backing allows the insulation to freely shift relative the support screen.