Masonite siding, more commonly known as hardboard siding, is generally made from compressed wood fiber, wood chips, wax and resin. When properly manufactured and installed, this type of siding can effectively protect a home from the elements. One important of aspect of Masonite or other hardboard siding installation is selecting the correct type of nails and using them correctly.

Hammer and nails
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Properly selected and installed nails will help allow hardboard siding to reach its full potential.

Suitable Nail Types

The best broad category of nail to use for Masonite and other hardboard siding application is stainless steel. High tensile strength aluminum nails may prove a more economical option. These nails will not discolor the siding and are corrosion-resistant but they cannot be used on galvanized flashing. Hot-dipped galvanized nails will typically be the least expensive nail option but they must be selected carefully to ensure that their use will not result in discoloration.

Heads, Shanks and Points

Nail heads, shanks and points must also be taken into consideration when selecting nails for hardboard siding. For panel siding, the head must have a diameter of at least .225-inch and a shank diameter of .092-inch. With lap siding, the acceptable minimum head and diameter is .24 and the acceptable shank minimum is .099. Nails with ring or spiral-thread shanks can be used in lieu of smooth shanks to increase holding power. Avoid using nails with needle points, as they tend to cause splitting. Instead, choose nails with blunt or diamond points.

Sizes for Different Applications

The proper nail size for hardboard installation varies between 6d, 8d and 10d depending on the specific siding application. As a general rule, the nail length must penetrate at least 1 1/2 inches into the framing. 6d, or 2-inch nails can be utilized to secure square edge panel siding or shiplap edge panel siding directly to studs. Nails that are 8d can be utilized to install lap siding directly to studs or apply square edge or shiplap edge panel siding over sheathing. Use 10d nails to place lap siding over sheathing.

Placement Considerations

Proper nail head placement is extremely important. Nails that are over-driven expose fibers and make the siding vulnerable to water absorption, causing the siding to swell and exposing even more fiber. The nail heads should either be snug against the siding surface or flush with the surface. Drive protruding nails in farther to correct them. If a nail is driven too far into the siding, corrective actions are generally warranted. If fiber is visible but the nail head is not sunk more than 1/16-inch deep, it can be resolved by simply painting over the nail hole. For deeper holes, fill the space with caulk. If the nail is sunk more than 1/8-inch into the siding, caulk the hole and drive a new nail in directly above or below the original nail.