Screws

Screws offer superior strength and holding capability compared to nails. Plus, if you ever need to take something apart, screws can be unscrewed with ease. While the benefits of screws are quite clear, have you ever wondered just how many types of screws there are?

Just like nails, screws come with different coatings to prevent rust. They are designed with four main head types and various slot configurations. Flat head screws are typically countersunk, so the screw’s head is either flush with or slightly below the surface. Oval head screws are partially countersunk, with the top of the head protruding a bit. Round head screws are not countersunk at all, with the full head sitting above the surface. Fillister head screws are raised above the surface on a flat base to protect the material from screwdriver damage during tightening.

In addition to the main types of screws, there are numerous others to discover, each designed for specific purposes. This article will explore a wide variety of screws, offering recommendations for common home repairs and tips on how to choose the best type for each task.

Drilling Screws and Pilot Holes

The majority of screws feature slot heads and are used with slotted, or standard, screwdrivers. Phillips-head screws have a cross pattern and are driven with Phillips screwdrivers. Screws are categorized by both length and diameter at the shank, measured by gauge number ranging from 0 to 24. Screw length is usually measured in inches. The length is critical as at least half of it should anchor into the material for proper holding.

Pro Tip: To avoid splitting the material, always drill pilot holes before driving screws. Pilot holes create a path for the screw to enter, minimizing the risk of damaging the surrounding material.

From Wood Screws to Machine Screws

For most household repairs, wood screws are generally sufficient. However, sheet metal screws, machine screws, and lag bolts also come in various designs. If you're replacing one of these screws, bring the old screw with you to the store. Below are some of the most commonly used screw types:

Wood Screws

Wood screws are typically constructed from steel, but if corrosion is a concern, consider using screws made from brass, nickel, bronze, or copper. For best results with wood screws, it's important to drill a hole first.

Sheet Metal Screws

This type of screw is used to join metal pieces together. As they are driven in, sheet metal screws create their own threads in the material. There are various kinds of sheet metal screws available. Pointed pan head screws, for instance, have coarse threads and are sold in gauges from 4 to 14, with lengths ranging from 1/4 inch to 2 inches.

Pointed pan head screws are ideal for use with light sheet metal. For heavier sheet metal, blunt pan head screws are preferred; they come in gauges ranging from 4 to 14 and lengths from 1/4 inch to 2 inches. Both types of pan head screws are available with either plain or Phillips-head slots.

Round Head Screws

Partial-tapping round head screws feature finer threads, making them suitable for both soft and hard metals. These screws are available in diameters ranging from 3/16 inch to 11/4 inches. Self-tapping round head screws, designed for heavy-duty use with thick sheet metal, come in diameters from 1/4 inch to 2 inches and lengths between 1/8 inch to 3/4 inch. Both types are available with either plain or Phillips-head slots and are perfect as self-tapping screws.

Machine Screws

Machine screws are blunt-ended screws used to secure metal parts. Typically made of steel or brass, they are also available with various coatings, including brass, copper, nickel, zinc, cadmium, and galvanized finishes, all of which help to prevent rust.

Machine screws come in all four primary head types -- flat, oval, round, and fillister -- and feature both plain and Phillips-head slots. They are commonly found in gauges ranging from 2 to 12, with diameters between 1/4 inch and 1/2 inch, and lengths from 1/4 inch to 3 inches.

Lag Bolts

For lighter tasks, screws can be held in place with anchors made of lead, plastic, or fiber. However, for larger projects requiring greater holding power, lead expansion anchors and lag bolts are the go-to choice. Often referred to as lag screws, lag bolts are heavy-duty fasteners that are driven using a wrench. They are mainly used to secure materials to masonry or wood framing. The anchors are inserted into pre-drilled holes in masonry, with the lag bolts then driven tightly into them.

Discover Countless Types of Screws

The variety of screws extends far beyond basic wood and machine screws, with a wide selection of types each designed for specific needs. For example, self-drilling screws combine the actions of drilling and fastening into one, eliminating the need to pre-drill a hole.

When a strong and reliable connection to a nut or tapped hole is necessary, machine screws and hex cap screws are the go-to solutions. For materials that require precise threading, thread cutting screws are an excellent choice as they create a threaded path while being driven in.

In woodworking, pocket hole joinery, utilizing specialized screws with a smooth shank and sharp tip, provides strong and discreet joints. Additionally, threaded hole fastenings, essential for mechanical applications, can be accomplished with a variety of screw types, each tailored to specific strength, material, and environmental needs.

Not quite what you're looking for? Consider these options: