Nails

Holding Power of Nails

In framing, nails should never be loaded in withdrawal (where the load acts parallel to the nail shank and tries to pull it out). Instead, framing nails should be loaded laterally (where the load acts perpendicular to the shank). Also, nails have more holding power when driven into the side grain rather than into the end grain. In fact, nailing into the end grain will reduce a nail’s lateral load capacity by approximately one-third.

Box vs. Common Nails

Lateral strength is largely a function of a nail’s diameter and the density of the type of wood into which the nail is driven. For example, 10d and 12d nails have the same diameter and the same lateral strength in each type of wood. Common nails are stronger than box nails because of their greater diameter (below).

Figure: Lateral Strength of Common vs. Box Nails

When substituting box for common nails, calculate the nail size needed using the conversion ratios shown below.

Withdrawal Strength of Nails

Nails are much stronger when loaded laterally (across the nail) than when loaded in withdrawal (along the length of the nail). Withdrawal from end grain is particularly weak and not accepted as a structural connection by most codes. Withdrawal values from sidegrain are given in the table below.

Toenails

For toenails loaded in withdrawal, multiply the values in the Withdrawal Strength Design Values table, above, by .67. For toenails loaded laterally, multiply the values in the Lateral Strength table, above, by .83. Toenails should be driven at an angle of about 30 degrees from the face of the stud or other member being attached (below).

Figure: Proper Toenailing

Pneumatic Nails

Pneumatic nails are typically sold by a specified shank diameter in inches (.120, .131, and .148 are common for framing nails). These are typically skinnier than common nails of equal length and, therefore, have lower lateral strength and withdrawal values (below). Consult manufacturers for lateral strength of specific nail types.

Stainless Steel Nails

While expensive, stainless-steel nails are the most rust-resistant under nearly all conditions. They are highly recommended below grade or in homes that will be exposed to salt air. They’re also recommended for cedar or redwood trim, and for siding that will be left to weather without stain or paint. Stainless-steel nails are typically available as Type 304 and 316. The 316 type are more durable.

Aluminum Nails

Aluminum nails are sometimes used to fasten exterior siding. They’re very resistant to rust and corrosion, but may corrode when used with some flashing metals.

Nailing Rules of Thumb

Typical nailing schedules appear in the table below.

Two is better than one. In general, never rely on a single nail. Use at least two.

Nail spacing. Don’t space nails closer than one-quarter their length to the edge of the board.

Nail penetration. To hold at full strength, nails should penetrate the wood a depth that’s at least 11 times their diameter — 1¹/2 in. for 8d nails and 1³/4 in. for 16d nails.