A nail is a steel pin with a point and usually a head, driven into timber to join components together. The joint works by friction: the timber closes around the shank and grips it. Unlike a screw, a nail cuts no thread — it forces the wood fibres aside.
Parts and sizing
A nail has a head, a shank and a point. Size is given as diameter × length in millimetres, for example 2.8 × 65; in imperial practice nails are still sold by length in inches. Plain shank nails drawn from wire are called wire nails or round wire nails.
- Head — flat and broad for holding power, or lost/brad head for work that must not show
- Shank — plain, annular ringed or twisted; rings and threads increase withdrawal resistance considerably
- Point — a sharp point penetrates easily but splits more readily; a blunt point pushes fibres aside instead of cleaving them
Types
- Round wire nail — the general-purpose nail with a flat head
- Lost head or oval nail — small head, punched below the surface with a nail set and filled
- Ring shank and twisted shank nails — for sheathing, decking and structural work where withdrawal must be resisted
- Masonry nail — hardened steel, driven into concrete and brickwork
- Coil and strip nails — for pneumatic nailers
- Clout nail — broad flat head, for felt and sheet materials
For external or damp conditions use hot-dip galvanised or stainless nails. Galvanised steel in contact with oak or cedar stains black through tannin reaction; use stainless there.
Rules of thumb
- Length. Roughly 2.5 to 3 times the thickness of the piece being fixed; at least two thirds of the nail should sit in the receiving timber
- Avoiding splits. Pre-drill in hardwood, near the end of a board or when using thick nails; a pilot of about 80% of the nail diameter is usual
- Spacing. Keep enough distance from the end grain and the edge, or the timber splits along the grain
- Skew nailing. Two nails driven at opposing angles hold far better than two driven straight
- Structural work. Trusses, sheathing and bracing have specified nailing patterns and quantities that come from the structural design, not from judgement
Related terms
- Wire nail
- Screw
- Nail set
- Timber joint
- Trenail
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