Abstract: An insulation product comprises an elongated blanket of fibrous insulation material having a facing on one major surface, the facing extending beyond the edges of the blanket to form opposed flanges, the flanges having first reinforcement fibers extending longitudinally along the outer edge zones of the flanges, and the flanges having intermediate zones positioned inwardly of the outer edge zones, and provided with second reinforcement fibers of a lesser density so as to provide a visual indication of the boundary between the outer edge zones and the intermediate zones of the flanges.