Masonite is a type of hardboard, a kind of engineered wood, which is made of steam-cooked and pressure-molded wood fibers in a process patented by William H. Mason. It is also called Quartrboard, Isorel, hernit, karlit, torex, treetex, and pressboard.Click to see full answer. Consequently, is Masonite board waterproof?Masonite composite hardboard has a natural moisture resistance. When you install Masonite, the area of the hardboard penetrated by a fastener can absorb moisture. To avoid structural failure of a piece of installed Masonite, you need to waterproof the surface of the Masonite after installation.Secondly, is masonite the same as MDF? Michele is right in that Masonite is a brand of hardboard, and MDF is a generic term for Medium Density Fiberboard. In respect to this, is Masonite dangerous? This product in its intact state is not classified as hazardous, but the dust from this product is classified as hazardous according to the criteria of the National Occupational Health and Safety Commission [NOHSC:1008(1999) and NOHSC:10005(1999)].Does Masonite board contain asbestos?No asbestos: it is not likely that your hardboard “Masonite” type board that was painted-over in oil or acrylic contains asbestos – hardboard is a wood or cellulose product.