Mapeguard UM is a lightweight underlayment membrane with superior performance for ceramic and stone tiles. It allows the for waterproofing and for the balancing of the vapor pressure, which helps suppress cracks. It is designed to perform on demanding substrates such as young concrete and 19mm (3/4") thick plywood with joists spaced less than 49cm (19.2"). Its unique 3-layer design absorbs the lateral stresses of the substrate without transferring these stresses to the tile, which allows the maintenance of exceptional adhesion and eliminates the risk of cracking.