Choose the right fastener for the job
It can be difficult to choose the right fastener for the job. Stand in the fastener aisle of any hardware store and you are confronted with thousands of options. But understanding more about the design and manufacture of fasteners can help you choose the right fastener for just about any job. If you choose the right fastener, it will help you deliver high-quality, enduring work.
All nails consist of a head, shank and point, each of which comes in various styles. The differences in these three sections are what make each nail better suited for a particular job.
Heads – Flat heads are the most common, providing a solid striking surface and solid holding power. Checkered flat heads help prevent hammer heads from slipping off while striking and are common for framing applications. Countersunk heads have a conical shape, allowing them to be driven beneath the surface of the material and then concealed for a smooth finish. Trim heads are very small and allow for easy concealment for such jobs as interior trim and cabinet making.
Shanks – Gauge refers to how thick the shank is, with lower numbers indicating thicker shanks. Smooth shanks are the most common and most versatile for everyday use. Barbed and screw shanks provide more holding power and are designed for use with hard woods or other dense materials. Ringed nails accomplish the same thing, but are designed for soft and medium-density materials (such as subflooring). Fluted shanks are typically exclusive to masonry nails, and they provide strong holding power while preventing cracking of the masonry.
Points – Diamond points are the most common and are well suited for general use. Long diamond points are sharper and designed for easier driving into harder materials. Blunt points reduce the chances of splitting the material to be nailed, but are more difficult to drive.
Screws are basically manufactured the same as nails, but instead of referring to the shanks, compare the threads. Screw sizes are numbers that refer to both the head size and shank thickness. Screw sizes go in ascending order, with a #4 screw being about half the size of the most common #8 screw.
Heads – Conical heads, like those found on most general purpose/drywall screws, can be driven just below the surface of the material being fastened, although not as neatly and cleanly as screws with countersinking heads. Pan heads are flat underneath so they hold tightly to the material without countersinking. Washer heads provide more holding power but are difficult to conceal, and trim heads are just the opposite. The heads also feature many different designs to fit different driving bits. Those other than slotted and Phillips screws are designed for better bit grip, minimizing stripped screws and premature cam-out.
Threads – Fine-threaded screws are sometimes referred to as machine screws and are typically used for attaching things to metal (drywall to steel studs, etc). Coarse threads provide strong holding power in wood and other like materials.
Points – Most common screw points, except machine screws designed for use with washers and nuts, are fairly sharp to start boring into the material at hand. Self-tapping screws feature an aggressive auger point to start sinking easier into denser materials and more difficult applications. Sheet metal screws and many deck screws feature self-tapping tips.
Many fasteners available today feature advanced coatings designed to protect them from the elements in exterior applications. Fastener materials such as aluminum and stainless steel are inherently corrosion resistant, but are often unsuitable for some applications where fastener strength is an issue.
This chart details the most common coating choices and a few points to consider.
|Electro galvanized||A thin layer of zinc is electroplated to the fastener||Less expensive, moderately effective. Most common with pneumatic fasteners|
|Hot galvanized||Fasteners are heated and tumbled through zinc powder or chips that bond to the surface||Less expensive, but coating can be thin and inconsistent. Not suited for heavy exposure to the elements|
|Hot-dipped galvanized||Fasteners are submerged in molten zinc||More expensive, very effective. Available in varying levels of thickness|
|Epoxy and ceramic coatings||Thin layers of epoxy or ceramic coats the fasteners||Moderately priced to expensive, depending upon coating thickness and quality. Very reliable|
For applications requiring more structural strength, such as deck railings, ledger boards, etc., you’ll have to move away from nails and screws and toward lag screws and bolts. For more specialized applications, there are fasteners such as staples, both small and untreated for installing fiberglass batting, and large and galvanized for attaching chain-link fencing to wooden posts, and cap nails, used for underlayment and house wraps.
Sometimes the intended application is clear from the name of a fastener – masonry screw, hard-cut flooring nail, aluminum soffit nail and sometimes it’s not – expansion bolt, box nail, brad. But the basic performance characteristics remain; the differences are in the heads, shanks/threads, points and coatings.
—By Roberto Franco