Coach screws, also sometimes called lag screws or lag bolts, are a type of heavy-duty screw commonly used for construction and woodworking projects. Designed to provide a strong and secure fixing, coach screws feature a sharp point and threaded shank for a strong grip into timber. Lag screws also have an hexagonal head that allows for tightening with a spanner or wrench for high torque. This type of screw is especially suited to heavy-duty applications like fixing beams or decking.