Fasteners for a lasting, firm hold

 

Anatomy of a screw

Close examination of screwheads reveals a whole world of engineering that governs their design. The more you know, the easier time you'll have choosing the right one.

Material: Exterior fasteners are made from various grades of case-hardened or stainless steel. While stainless-steel products are left bare, all others have layers of electroplated zinc coatings and sometimes a polymer coating for color or lubrication. Or they're dipped in molten zinc to prevent corrosion. Note that yellow zinc and black screws (not shown in this article) are often not suited for the rigors of exterior use.

Head size: With large-headed screws, your fastener's visibility increases and countersinking becomes harder and time-consuming. Further, the chances of splitting the wood increase. Many types of trim-head exterior screws, such as GRKs, come with head sizes similar to a same-size finish nail, making them less noticeable.