Drywall screws are manufactured in various sizes to better accommodate each individual job. Screws that measure 1-1/4 inch in length are appropriate for sheets of drywall that are 3/8, 1/2 or 5/8 of an inch thick, while screws that measure 1-3/8 inches are meant for sheets of drywall up to ¾ of an inch thick. Drywall sheets of a larger thickness, such as 7/8, 1 inch or 1-1/4 inch, require a screw length of 1-1/2, 1-5/8 or 2 inches respectively.
Black drywall screws feature a coarse thread that is better suited for attaching drywall to wood. Silver screws are typically manufactured with a fine thread, which lends itself better to metal framework. Both types are made in different lengths to accommodate the various thicknesses of drywall board.
Additional layers of drywall can be installed on top of each other to boost insulation, soundproofing and fire rating. In this case, a screw size of 1-1/4 inch can be used for installing the base layer while a screw size of 1-7/8 inch is required for the second and any additional layers.
Drywall screws aren’t inserted by hand. Instead, professional drywall installers use a screw gun -- powered by either the electricity in a home or rechargeable battery -- to insert screws in a fast, safe and efficient manner. Some screw guns are equipped with a self-loading mechanism. This uses a plastic ribbon of screws that are automatically fed onto the tip of the screw gun, thus saving the drywall installers the hassle of having to retrieve a new screw each time.