Masonite siding is a combination of wood chips and products that bind them together (a type of glue or wax). While this product is strong, somewhat pliable and comes in several colors, it does have its drawbacks. It requires more care than vinyl siding and, as a wood product, is susceptible to insect infestation, mold and mildew and shows wear and tear after a few years. Like a wood deck or fence, it would require periodic maintenance. A home siding professional could best determine exactly what product was used on your home if you can't contact the builder directly.