Drywall has been a standard building material for over 100 years. In its earliest days, it was not the most popular method for finishing interior walls, but with the housing boom after WWII, it became more widely used. Drywall, also known as sheetrock, whiteboard, or gypsum board, is inexpensive to produce and install. Unlike the previous method of finishing walls—plaster and lathe—it doesn’t require the same level of craftsmanship to achieve a smooth final finish.
At its most basic level, drywall is a mixture of gypsum and other materials that are sandwiched between smooth paper layers. The gypsum gives the drywall a texture similar to concrete, which also helps it be fire-resistant.
How Drywall is Affixed
When it was originally introduced in the early 20th century, nails were used to attach drywall to the stud walls. There are a few issues that come from using nails—over time, any settling of the walls will loosen the adhesion. Also, hammering nails into drywall can leave marks that need to be smoothed over during the mudding phase.
Eventually, the use of drywall screws helped to solve some of these problems. The threads on the screws give a firmer, tighter grip through the drywall and into the wooden stud, so there are fewer issues with settling. Drilling with screws is also quicker and more accurate, with less damage done to the drywall surface, so there is less work to do at the mudding stage.
To begin with, check your building codes to see if there are local requirements regarding drywall installation. The number of screws to use in your drywall installation for the best results is pretty standard.
Using Drywall Screws
Most interior walls for residential homes are built with studs 16 inches on-center. For a drywall sheet that is 4’ x 8’, the sheet—when hung perpendicular to the studs—would cover 6 studs. There should be one screw through the drywall to each stud and they should be spaced 16 inches along the length of each stud.
This means that on a 4’ x 8’ there should be a total of 24 screws (6 across and 4 down) in each sheet of drywall. For a 4’ x 12’ sheet of drywall, this same calculation would mean that 40 screws would be used (10 across and 4 down).
For drywall sheets that are near the edge of the wall or ceiling, it is usually recommended that the spacing be decreased to 7 or 8 inches. This will allow for a stronger bond in the room’s corners and ceilings. Many contractors will use tighter spacing for screws on all ceiling drywall sheets.
Remember to check your local building codes and see if there are manufacturer’s recommendations before determining your plan for installing your drywall.
Drywall comes in different thicknesses because not all areas of a project require the same strength. A thickness of ½” is pretty standard for most jobs. Keep in mind that the thinner the drywall, the more screws may be required for stability. The thicker the drywall, the more difficult it may be to lift and install. Also, the thicker it is, the more soundproofing it provides.
Drywall screws are the ideal fastener to use. Because drywall is intended to be most effective dry, most drywall screws are made from steel. It is strong and will move smoothly through the drywall and into the wooden studs. If moisture were a problem, steel screws would eventually rust and could cause issues.
It is recommended that most drywall screws be at least ¾” longer than the thickness of the drywall being used. As the drywall thickness goes up, so should this proportion of screw length to drywall thickness.
This will ensure that the screw goes far enough into the wood studs to have a strong grip, but not so deep that it damages the studs. For ¼” drywall, plan to use screws that are 1” to 1 ¼” long. For ½” drywall, use 1 ¼” to 1 5/8” screws. For ¾” drywall, use 1 5/8” to 2” screws.
Drywall screws also come in different thread gauges—coarse and fine. For most residential installations with wood studs, coarse threading is less expensive and more effective. Fine threads are usually used for installations that use metal studs. In fact, using finely threaded drywall screws in wood may mean you don’t get as good adhesion to wood studs.
If you own an older home with drywall that was fastened with nails, you may notice the occasional nail pop. This happens when the drywall settles over time. Drywall screws can be useful to help fix nail pops.
Just remember that drywall screws are fashioned specifically for use in installing drywall to wall studs. Sometimes builders use them for other purposes, like screwing wood pieces together. Because they are not designed for this, there may be a tendency for the screw heads to snap off. For other non-drywall projects, it is recommended that you look for fasteners that are made for that project.
Types of Drywall
Regular drywall is often referred to as whiteboard or gypsum board. This is because the primary material used is crushed gypsum sandwiched between two smooth paper surfaces. It is meant for use in many interior applications and should not get wet. It has fire-resistant properties and is good at providing a sound barrier between rooms.
Green board is a more common name for drywall that is mold-resistant. It is still made with crushed gypsum, but it is sandwiched between two thicker paper surfaces that have also been treated with a wax substance to increase the moisture resistance. It can also include a fiberglass mesh that deters mold growth by removing materials that could become food needed by mold to grow.
Green board is used in areas where moisture is more of an issue, like kitchens, laundry rooms, and bathrooms. Green board is also useful as a backing for tile surfaces. When using mold-resistant drywall, pay attention to the manufacturer’s instructions and use mold-resistant mud.
Fire-resistant drywall is a specialized form that is used in basements, garages, or anywhere there is equipment or materials that might be flammable. This type of drywall has fiberglass mixed in with the gypsum, so it slows the progress of a fire. It can be layered for additional fire resistance.
Plasterboard is a form of drywall that is sometimes referred to as blue board. Unlike standard drywall, blue board is not mudded but covered all over with a thin layer of plaster. This type of drywall is usually used in older homes to mimic the appearance of plaster and lathe work.
Installing blue board requires a skilled hand at plaster application to achieve a smooth look, so you may want to work with a knowledgeable professional.
If the standard level of soundproofing is not sufficient for your project, there are soundproof drywall products that add polymers and wood fibers to the gypsum for decreased sound transmission.
This is often used for walls that divide separate living spaces, like in apartments, hotels, or duplexes. However, it is denser and therefore heavier than standard drywall, so exercise caution when installing it.