One gallon of TAVY Thin-Skin #007 Glue will cover 100 square feet * Requires one roll of TAVY Thin-Skin Underlayment. Sold Separately. Amazon item # B000ND18E6 * Tested by Tile Council of America * The TAVY Thin-Skin Two Part Underlayment System was developed to provide an underlayment for tile that could be installed over any surface without adding additional height to the sub-floor. * TAVY #007 Glue is a high-end multi-purpose adhesive high in solids, which will adhere to any surface.