The Ultimate Guide To Drywall Screw Sizes

Drywall screws are used to fasten sheets of drywall to wall studs or ceiling joists. The type of screw you need depends on the thickness of the drywall and the material of the stud. For example, coarse-threaded screws are used to attach drywall to wooden studs, while fine-threaded screws are used for metal studs. The length of the screw is also important – it should penetrate the stud by at least half an inch, but this will depend on the thickness of the drywall and the type of stud.

Coarse vs Fine Threaded Screws

Drywall screws are used for fastening sheets of drywall to wall studs or ceiling joists. They are usually made of steel and require a power screwdriver to be drilled into the drywall. The two most common types of drywall screws are the S-type and the W-type.

S-Type Screws

S-type screws, also known as fine-thread drywall screws, are used for attaching drywall to metal. The threads of these screws are closer together and have sharp points to make surface penetration easier. Fine-thread screws work better with metal because they are self-threading and have a higher tensile strength. They also have a very shallow pitch, which makes vibrations less effective at loosening fasteners over time, making them ideal for environments where vibration is an issue.

W-Type Screws

W-type screws, also known as coarse-thread drywall screws, are used for installing drywall onto wood. The threads of these screws are further apart, and the coarseness of the threads pulls the drywall against the studs, tightening everything together for a firm hold. Coarse-thread screws are also more tolerant of damage and are less likely to gall than fine-thread screws. They are also better at handling obstructions, such as dirt, in the threading.

Other Considerations

When selecting the correct fastener for a job, it is important to consider the specific application. As a general rule of thumb, coarse thread fasteners should be used in brittle applications (e.g. plywood, OSB, SPF) or thin-gauge metal applications, while fine thread fasteners should be used in thick-gauge metal applications.

Screw Length

The length of a drywall screw depends on the thickness of the drywall panels and the material of the studs.

For 1/2-inch drywall, use 1-1/4-inch or 1-3/8-inch screws for wood studs. For metal studs, it is recommended to use shorter screws, such as 1-inch ones, to avoid damaging the metal.

For 5/8-inch drywall, use 1-3/8-inch, 1-5/8-inch, or 2-inch screws.

For 1/4-inch drywall, use 1- to 1-1/4-inch screws.

It is important to note that the length of the screw should be at least 10 mm more than the drywall thickness. Additionally, the screw length should penetrate the stud by at least 1/2 inch.

Screw Diameter

The gauge of a drywall screw refers to its diameter. The gauge is expressed as a number, and as the gauge number increases, so does the diameter. For example, a #6 drywall screw is thinner than a #8 drywall screw.

The most common gauge numbers for drywall screws are #6, #7, #8, and #10, with #6 and #8 being the most frequently used.

On product labels, the gauge is usually the second number after the length. For instance, a 1-5/8-inch long screw with a #6 gauge would be written as "1-5/8 inch x 6".

The actual sizes for #6 and #8 gauge screws are 0.1380 inches and 0.1640 inches, respectively.

When selecting the appropriate gauge, it is important to consider the condition of the studs. For attaching drywall to studs in good condition, a #6 gauge is typically used. However, if you are driving screws into older wood that requires more gripping power, a thicker #8 gauge is recommended.

Screw Head

The screw head is an important feature to consider when choosing the right drywall screw for your project. The head of a drywall screw is typically bugle-shaped, which helps the screw stay in place without tearing through the outer paper layer of the drywall. This cone-like shape tapers down into the drywall after installation, providing a clean and finished look.

Drywall screws are available with different head styles, including flat or bulge heads. The type of head you choose will depend on the specific application and material you are working with. For example, when attaching drywall to metal studs, use drywall screws with smaller heads, also known as fine drywall screws.

Most drywall screws have a Phillips head, which is the standard for this type of screw. However, other types of screws, such as construction screws, are starting to adopt different head types, such as Torx or square. The Phillips head is designed to work with a #2 Phillips head drill-driver bit, making it easy to drive the screws into the drywall.

In addition to the shape and style of the head, the coating of the screw head is also important to consider. Drywall screws are often coated with phosphate, which provides better protection against rust compared to zinc coatings. Both gray and black phosphate coatings are common, but it's important to choose the right colour to avoid staining. Black phosphate, for example, may stain due to the oil used in the coating.

Screw Material

Drywall screws are typically made of steel, specifically case-hardened steel. The standard material for drywall screws is low carbon steel. To protect the screw from corrosion and rust, it is often coated with phosphate (either gray or black). This is particularly important if the screw will be exposed to moisture.

For additional corrosion resistance, some drywall screws have a thin vinyl coating. These are ideal for use in areas with high humidity.

For use with green board drywall, which is water-resistant and used in wet or moist areas, you should use galvanized drywall screws.

If you are installing drywall in an area that will support a ceiling fan, do not use drywall screws. Raw steel screws will rust over time, and your wall panels may fall off as a result. Instead, use hot-dipped galvanized fasteners or stainless-steel screws.

For cabinet installation, drywall screws with yellow zinc plating are often used. This plating gives added corrosive resistance and looks great with wood.

For outdoor use, stainless steel is a good option for its high resistance to rust.

Frequently asked questions