Shop for Building Materials at The Home Depot. Beautiful crown moulding is a great way to separate and define each room. With each design modeled after traditional plaster type mouldings, our lightweight polyurethane mouldings give the same rich detail, yet at a fraction of the cost. Most moulding profiles can be partnered with our do-it-yourself corner blocks that means no miter cutting for you and most rooms can be completed in ours instead of days. Another benefit of polyurethane is it will not rot or crack and is impervious to insect manifestations. It comes to you factory primed and ready for your paint, faux finish, gel stain, marbleizing and more.