Henry 176 Pond Patch is an innovative method for filling and leveling roof "ponds" to assure positive drainage. Extremely versatile, it can be used over the roof membrane for maintenance or under the new roof membrane in reroofing applications. Henry 176 Pond Patch is strong, durable, has great compressive strength (125 psi) and will not burn. It is convenient to use, mixing readily with water to create a trowel grade material, which is easily shaped and worked. At less than 3# per sq. ft. per inch of thickness, Henry 176 Pond Patch is very light weight (approximately 33# per cu. ft.) It also reduces the destructive potential of "ponding” water on roof structures.