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.

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.

Prevent rot in roofs, decks, and outdoor posts. The rubber-backed washer in these screws keeps fluid out of fastened joints. They're made of stainless steel, so they won't degrade from chemically treated wood, such as ACQ-treated (arsenic-free) lumber. Also known as trim head screws, they exert less pressure on surfaces to curb splitting and distortion. The square drive handles more torque than slotted and Phillips drives, so it's less likely to slip.

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.