Often used on posts and beams, the coarse threads on these screws dig in for a firm hold. 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. Length is measured from under the head.

Fasten decking and fencing outdoors with screws that won't rust. They're often used with chemically treated wood, such as ACQ-treated (arsenic-free) lumber. Also known as deck screws, their trumpet shape spreads pressure to prevent splitting, while the flat head limits snags. The square drive handles more torque than slotted and Phillips drives.

The screw drill tip acts as a built-in pilot, though pilot holes are still recommended near edges to avoid 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.

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.

A built-in flange protects surfaces from splitting and pull-through by spreading pressure over a large area. These screws won't rust, so you can use their coarse threads to secure posts and beams outdoors. They also won't degrade from 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 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.