Henry 542 Liquid BackerBoard is a Portland cement based self-leveling underlayment. It is the fastest and easiest way to prepare wood floor for the installation of ceramic tile. It soothes wood without the need for lath mesh. It can be used over concrete surfaces and radiant heated flooring. Installs up to 70% faster over plywood compared to other products. Lowers the install cost with the coverage the product provides as well as the no need to lay metal lath. Covers 52 sq. ft. at 1/8". Bonds well to plywood, concrete, existing tile, and even gypsum substrates. May also be used on vinyl, wood and laminate. Excellent flow, longer working times and better healing then competitive products. Just mix and spread. Entire installation may be done standing rather than on your hands and knees. You have a 10 minute working time and may walk on in 3 hours. In just 6 hours you may install tile. Pour up to 1-1/4" thick neat. Be sure to use primer prior to installing, Henry 554. For indoor use only. Made in the USA.