Tile Backer boards are substrate materials you can tile directly onto. Unlike plywood and other substrates that warp, backer board is hard, flat and won't buckle. Its stability allows you to tile using a thinset mortar, making it easy to create a level and consistent tile surface. Tile backer boards are also waterproof, ideal for bathroom and wet room installations. They also have insulating properties too and can make your underfloor heating system more energy efficient.