Screw Head and Drive Types Explained

Head geometry is about bearing area and height

Every head style trades those two against each other. A wide head spreads load and resists pull-through; a low head keeps out of the way of whatever comes next. Most specification arguments come down to which of the two is the binding constraint.

Bugle head

A curved profile that sinks into a soft face without cutting it. Designed for plasterboard, where the head has to finish just below the paper surface without breaking it. Useless on steel, where there is nothing to sink into.

Pan framing head

A pan head flattened so that board laid over it sits flat. Used at stud-to-track junctions in light steel framing where head height directly affects the finished surface.

Modified truss head

The widest low-profile head in common use. Large bearing area without the height of a washer head, which suits soft board, thin sheet and anything that a smaller head would pull through.

Hex washer head

An external hexagon with an integral flange, driven by a socket. No recess to strip, and it is the head that carries a bonded sealing washer for roofing and cladding.

Countersunk and double countersunk

Countersunk pulls flush. The double countersunk version used on chipboard screws adds a second shallower cone with ribs that cut the panel face rather than dragging it upwards.

Why Torx replaced Phillips on long screws

Phillips is designed to cam out. On a hand screwdriver that protects the screw from over-tightening; on an impact driver running a 200 mm timber screw it destroys the head. Torx transmits torque through flat walls and does not slip. Square drive sits between the two and retains the bit better without magnetism.