UK Nail Sizes — Types, Gauges & Uses

For structural timber framing in the UK, 75 mm or 90 mm round wire nails (3.35 mm or 3.75 mm diameter) are standard. Use 90 mm nails for 47 mm timber where you need to penetrate at least 40 mm into the receiving timber. Galvanised nails are recommended for any timber in contact with treated wood or exposed to moisture.

Bright (plain steel) nails are untreated and suitable only for interior, dry applications. Galvanised nails have a zinc coating for corrosion resistance and are essential for exterior use, treated timber, and damp locations. Stainless steel nails offer the highest corrosion resistance and are required for coastal or highly corrosive environments, and for use with cedar or oak (which contain tannins that react with zinc).

Ring shank (annular ring) nails have ridges along the shank that dramatically increase holding power — typically 40-100% more pull-out resistance than smooth shank nails. Use them for plywood and OSB sheathing, roofing felt, softwood flooring, and any application where vibration or movement could loosen smooth nails over time.

For roofing felt, 20 mm extra-large head (ELH) clout nails with a minimum 10 mm head diameter are standard. For slate and tile battens, 65 mm aluminium or galvanised clout nails are typical. The large head prevents the nail pulling through thin sheet materials.