Fiberock AquaSmart Panel features a homogenous waterproof composition, engineered to perform using proprietary waterproof technology. The panels provide added durability and superior performance (vs. traditional tile backerboards) and are manufactured to meet ANSI 118.10 Section 4.5 for waterproofness. At 0.42 in. thick, USG Fiberock® AquaSmart™ Tile Backerboard meets or exceeds the 3/8 in. thickness mechanical property requirements in accordance with ASTM C1278 Standard Specification for Fiber-Reinforced Gypsum Panel. With its enhanced performance, wall installation is easy. Install the panels on studs with up to 16 in. o.c. spacing and treat joints and fasteners with USG Durock™ Brand Waterproofing Membrane Band or USG Durock™ Brand Liquid Waterproofing Membrane.