Carrying load across the nail rather than along it - shear, not withdrawal.

A plain round shank resists a load trying to slide one member past another very well.

Against a load pulling the nail straight out, only friction on the shank resists, and that is a fraction of the shear capacity.

Framing and carcassing connections are detailed to load nails in shear for exactly this reason.

Where withdrawal governs - sheathing, decking, anything lifting - a ring or twisted shank is the correct nail.

The large flat head is part of the strength, since it prevents the nail pulling through softwood.

Position matters more than technique - stay away from ends and edges, and stagger the pattern.

Timber splits along the grain, so several nails in line on one grain line will eventually open it up.

End distance is the most restrictive dimension, because there is very little strength holding the end together.

Blunting the point with a light tap makes it crush fibre rather than wedge it apart, which is an old technique that genuinely works.

Pre-drilling at slightly under the shank diameter is the reliable answer in dense, dry or thin timber.

Dry timber splits far more readily than green or freshly treated timber.

Galvanised as a minimum, stainless where staining is unacceptable or exposure is severe.

Bright nails are for dry interior work and rust quickly anywhere else.

Hot-dip galvanising gives a thick, robust coating and is the general external choice.

Electro-galvanised is much thinner and is not an external finish despite the name.

Several timber preservatives are hostile to zinc, so the compatible fastener finishes are listed by whoever treated the timber.

Stainless avoids the staining that a corroding nail produces around its head, which matters on anything visible.

By length and shank diameter, though the conventions differ between markets.

Metric practice quotes length by diameter in millimetres, which is unambiguous.

Some markets use a gauge number for diameter and others a traditional penny sizing for length, neither of which translates directly.

Because of that, cross-market substitution is best done on the actual dimensions rather than on the size name.

Length is chosen so the nail penetrates the second member by roughly two-thirds of its length in general framing practice.

Diameter is the variable that drives both holding power and splitting risk.

Long enough that most of its length is in the member being fixed into - as a rule of thumb, around two-thirds.

The holding is developed in the second member, so penetration there is what matters.

Too short and the nail relies on very little engagement; too long and it protrudes, which is both a hazard and a sign the wrong size was chosen.

Where a designed connection is involved, penetration depth is specified rather than estimated.

Skew nailing changes the geometry and generally needs a longer nail for the same effective penetration.

Nailing into end grain gives much lower holding than into side grain and should be avoided where it matters.

Yes, as collated strips or coils - but the collation must match the specific tool.

Collated nails are joined by paper, plastic or wire into strips or coils for feeding.

Strip angle, collation material and head type are all tool-specific, and a nail that physically fits may still jam.

Clipped-head and full-round-head collated nails exist, and some specifications require full round heads.

The tool manufacturer lists compatible nails, and that list is the one to buy from.

Gun nails are usually slightly smaller in diameter than equivalent hand-driven nails, which affects holding power.

When the joint must be demountable, when withdrawal governs, or when the fixing must not be worked loose by movement.

Nails are faster and cheaper and carry shear well, which is why framing is nailed rather than screwed.

Screws hold far better in withdrawal and can be removed without destroying the timber.

Repeated movement - decking, sheathing on a moving frame - works plain nails loose over time.

In designed connections the specification names one or the other and they are not interchangeable.

A ring shank nail sits between the two, giving much of a screw's withdrawal resistance at nailing speed.