A fabric substrate suitable for lining between a cast and a person. The fabric substrate includes a pair of opposing faces formed by pillar and inlay stitches. The fabric is constructed at least in part of hydrophobic, water-resistant yarns configured to provide enhanced water resistance and sufficient stretch in both a length and width direction to facilitate conforming the undercast liner around the anatomical shape without wrinkling during application. An intermediate tying layer spans between the opposing faces, and the tying layer includes elastic yarns stitched in a V stitch pattern such that the elastic yarns extend between one opposing fabric face and the other face.