A built-in flange protects surfaces from splitting and pull-through by spreading pressure over a large area. These screws are often used to secure wooden posts and beams because their coarse threads dig in. The hex head's six contact points keep sockets in place to avoid slipping and stripping the drive. To tighten, use a wrench or six-point hex socket. Also known as lag bolts.

Drill a pilot hole slightly smaller than the screw to prevent splitting. Head height includes the flange. Length is measured from under the flange.

Fasten wood to sheet metal while reducing stripping and pull-out. The dual threads on these screws grip both materials at the same time, so they install quickly, require less torque, and resist vibration. Also known as trailer floor screws, these screws are often used to fasten wooden boards to metal trailer frames. With a deep six-lobe opening, Torx drives handle more torque than slotted, Phillips, and hex drives. The flat head deters snags.

Drill a pilot hole slightly smaller than the screw to prevent splitting. Length is measured from the top of the head.

With coarse threads that dig in, these screws secure posts and beams in outdoor and wet environments. They won't degrade from moisture or chemically treated wood, such as ACQ-treated (arsenic-free) lumber. The hex head's six contact points keep sockets in place to avoid slipping and stripping on the drive. To tighten, use a wrench or six-point hex socket. Also known as lag bolts.

Drill a pilot hole slightly smaller than the screw to prevent splitting. Length is measured from under the head.

Also known as hanger bolts, use these studs to hang, mount, and fasten parts to wood structures. Install them with a stud driver, or create wrench flats by threading two nuts onto the stud and jamming them together.