A drywall screwdriver is a power tool specially designed for use in installing drywall, also known as Sheetrock or gypsum board. It uses special bits that release drywall screws before they rupture the drywall’s paper skin. Most look very similar to power drills and are either corded or powered by rechargeable batteries.
Drywall is essentially a layer of plaster between two sheets of very heavy paper, and it is attached to wooden or steel studs to make walls and ceilings. It’s fairly heavy — a standard 4-foot by 8-foot (1.22 M x 2.44 M) sheet weighs close to 55 lbs (25 kg). The installation guidelines recommend screws no more than 16 inches (41 cm) apart, meaning that a single standard sheet might have as many as 32 screws.
The main function of a drywall screwdriver is to rotate the screw bit at a good speed for driving a Sheetrock screw through the drywall and the stud to which it’s being attached. A regular power drill can be used for the same purpose, but the speed must be carefully moderated; if operated at full speed, there’s a good chance that even with the special drill bits, the screws may be driven too deep. The screwdriver bits have a collar that acts as a stop, preventing the bit from following the screw head into the drywall — once the collar contacts the drywall’s skin, the bit can’t proceed any further. Thus, the spinning bit continues turning the screw, which continues its forward motion into the drywall and pulls away from the bit. At this point, the screwhead has stretched and dimpled the drywall’s skin, but not ruptured it.
A standard drywall screw is self-tapping, which means that there’s no need to pre-drill a hole, and is very sharp. It has a tapered head called a “bugle” head, because it looks like the mouth of a bugle. The bugle head allows the screw to hold the drywall the way the head of a nail holds wood it’s driven into.
Besides a power drill, there are three other alternatives to a drywall screwdriver: a manual screwdriver, a drywall hammer with drywall nails, and construction adhesive. Manually driving Sheetrock screws is time-consuming and physically-demanding and is more likely than a drywall screwdriver to rupture the skin. A drywall hammer with drywall nails can also be time-consuming, and the potential for major damage to the drywall’s skin is much greater. Construction adhesive, on the other hand, is gaining popularity with construction professionals, especially when used in conjunction with screws.