Drywall - An In-Depth Guide

What Is Drywall?

Drywall is a flat panel used in the construction of interior walls and ceilings. It's durable, easy to install, and simple to repair when damaged. Architectural features such as columns, arches, and eaves can be built using drywall. While drywall is the most commonly used name, some refer to it as wallboard, gypsum wallboard, sheetrock, and plasterboard.

What Came Before Drywall?

Before the appearance and popularity of drywall, the vast majority of home interiors in the United States were "finished" with plaster. However, this process was labor-intensive, time-consuming, and added to the overall construction costs of homes. By the middle of the 20th century, drywall became the most prevalent way to construct ceilings and interior walls.

What Is Drywall Made Of?

Drywall is made of calcium sulfate dihydrate (gypsum). The gypsum sheets are placed between thick facer and backer paper sheets because of its soft nature and tendency to break or dust. In most drywall products, the gypsum is mixed with fiber, such as paper or fiberglass, for added strength and consistency. Additives, foaming agents, and plasticizers are added to increase fire resistance and flexibility and reduce weight, moisture, and mildew.

How Thick Is Drywall?

Drywall is commonly found in 1/4 inch, 3/8 inch, 1/2 inch, and 5/8 inch thicknesses. While 1/4 inch and 3/8 inch are ideal for creating architectural features and repairing damaged drywall, the standard residential thickness is 1/2 inch. 5/8 inch drywall is primarily used in commercial construction or in residential settings where soundproofing is required.

How Much Does Drywall Weigh?

While the weight can be impacted by thickness, type, manufacturing, humidity, and other minor factors, here are some general guidelines you can follow:

• 1/4 inch = 1.1 - 1.2 lbs/ft2
• 3/8 inch = 1.3 - 1.4 lbs/ft2
• 1/2 inch = 1.3 - 1.6 lbs/ft2
• 5/8 inch = 1.6 - 2.2 lbs/ft2

How Do You Cut Drywall?

Cutting drywall is relatively easy. You'll require a pencil, T-Square for a long straight line, and a utility knife. From here, it's just score, snap, and cut.

1. To score the drywall, draw a straight line with the T-Square from top to bottom and use your utility knife to cut the paper layer of the drywall along the line.
2. Snap the drywall by pulling from the side where you made the cutting line.
3. Cut the drywall paper layer on the back to separate excess piece of drywall.

What Grit Sandpaper Should You Use on Drywall?

Sandpaper is often used on drywall between the joint compound and taping phases or during drywall repair. 100 to 120 grit sandpaper is recommended to level off the compound with the drywall quickly. A sanding sponge or 200 to 220 grit sandpaper is then used to smooth the surface.

Can I Recycle Drywall?

One of the biggest challenges that many homeowners face when renovating their home insides is finding a recycling company for drywall. Recycle Nation offers an interactive map to help you search for drywall recycling companies in your area. USA Gypsum is a significant player in the drywall recycling industry, handling over 30,000 tons annually from 9 states. You can contact them here to see if they service your region. In addition, your local government can tell you whether they offer a bulky waste recycling program specifically designated for construction waste. 

In Canada, various companies collect drywall waste for recycling, like Trash King in British Columbia. In Toronto, drywall is commonly separated and recycled by bin rental services like Gorilla Bins. They sell the waste for recycling to larger sorting and recycling facilities like GFL.

How is Scrap Drywall Recycled?

You cannot simply place your old drywall on the curb for the recycling truck to pick up. However, many companies will recycle your drywall and other construction materials. The process is relatively simple as the paperboard that encases the gypsum is removed along with any nails or screws. The encased gypsum is then either ground into a powder or formed into pellets and sold back to companies using gypsum in various products, including new drywall, agricultural fertilizers, or an ingredient in Portland cement.

Can I Buy Recycled Drywall?

Yes! There are two different types of recycled drywall products that homeowners can find on the market. You can find drywall products that incorporate various recycled gypsum and other products that use synthetic gypsum made with recycled materials.  Georgia-Pacific's "ToughRock" drywall, for example, comprises between 6 and 26 percent of recycled content, depending on the manufacturing facility. Unfortunately, it can be hard to accurately determine which companies or products use the most recycled gypsum.

What Are the Benefits of Recycled Drywall?

Most environmental issues associated with the mining, producing, and discarding of drywall can be avoided by purchasing recycled drywall. Gypsum makes up at least 90 percent of the weight of a sheet of drywall. Gypsum can be recycled to manufacture new drywall sheets, cement production, an agricultural fertilizer, or an additive to composting operations.

The exact recycled content of gypsum will depend on the manufacturer. However, consumers should be careful to look for greenwashing practices unfortunately used by many in the industry. Some companies use the "recycled content" claim only to refer to the recycled face and paper backing. At the same time, they don't incorporate recycled gypsum into their products.

Does Drywall Off-Gas?

Historically, because drywall is made mainly from gypsum, a natural material, off-gassing was not generally seen as a problem. About a decade ago, however, imported drywall from China was found to contain high levels of sulfur. This toxic drywall was installed in over 100,000 homes between 2004 and 2007. It led to a horrible rotten egg smell, blackened or corroded plumbing pipes, the failure of air conditioners and other household appliances, and severe health problems such as asthma, coughing, and irritated eyes. Since that toxic drywall was removed from the market (and the affected homes), off-gassing has been less of an issue. However, always purchasing drywall made in North America is an excellent strategy to avoid potential problems.

Is There Formaldehyde In Drywall?

Formaldehyde is a known carcinogen that is unfortunately present in several building materials, including carpets, drywall, sealants, etc. Some drywall manufacturers include formaldehyde as part of their plasticizer in gypsum production. However, a more common source of formaldehyde is the drywall joint compound. This compound is used to "connect" two drywall sheets. It might include acetaldehyde, another known carcinogen, and crystalline silica, a carcinogen when inhaled. To avoid this contamination source, make sure only to use joint compound (or drywall "mud") labeled as low-VOC and formaldehyde-free. Even better, consider using CertainTeed's Air Renew drywall, which actively cleans your indoor air quality by absorbing formaldehyde from the air.

How Can I Avoid Mold on Drywall?

You can avoid mold growth on your walls using a dehumidifier to keep the humidity level under 60 percent. Moss walls and living walls can be innovative (and beautiful) ways to naturally regulate your home's humidity levels. For kitchens, bathrooms, and laundry rooms with drywall, dry up any spills or standing water quickly and repair leaks as soon as they are detected. Smart water leak detectors can protect your drywall while saving homeowners from potentially costly and damaging plumbing leaks. Drywall products that use fiberglass (instead of paper) for the front and back encasing are less prone to moisture issues such as mold and mildew. While fiberglass-encased drywall is costlier, it might be a good investment for bathrooms, kitchens, and other "wet" rooms in your home.

How Can I Remove Mold from Drywall?

Another major problem associated with drywall is excessive moisture leading to mold and mildew growth. If your drywall exhibits the green, brown, or blacks spores of mold growth, you need to act quickly to stop the mold from spreading. A simple cleaning solution made with one part baking soda and five parts water works well for mild mold cases. For more severe problems, mix one part of bleach to three parts water. If you don't want to use bleach, combining equal parts of white vinegar and water can naturally kill off mold spores on your walls.