The Functionality of Drywall

Every day, you pass by countless sheets of this material. It's found in your home, office, and nearly every store you step into. Known by many names—Sheetrock, wallboard, plasterboard, gypsum wallboard, or simply drywall—this ubiquitous material is rarely understood in terms of its production, origins, or its full range of practical applications.

Drywall is a widely used building material for constructing walls and ceilings. It’s also used for creating various design elements like eaves, arches, and other architectural features. Drywall installation is quick and straightforward, and its durability makes repairs easy. In commercial buildings, drywall is commonly used to encase steel beams within columns and is a cost-effective way to cap masonry walls above ceilings. It also serves as an important fire-resistant barrier in walls and ceilings, helping to slow the spread of flames and allowing for safer evacuations during emergencies.

Before drywall became the go-to material, interior spaces were built using plaster. For centuries, builders would layer wet plaster over wooden strips called laths to form walls and ceilings. Although it eventually hardened into sturdy walls, the process of installing and repairing plaster was labor-intensive and time-consuming. The plastering process required multiple layers, each with a long drying period, and was physically demanding, requiring skilled craftsmen to work tirelessly on small sections of wall over weeks.

Walls that would have taken weeks to build using plaster can now be completed in just a few days with drywall. Not only is it faster, but drywall also outlasts plaster and comes at a lower cost. If damaged, drywall can be repaired much more quickly and easily, and it offers superior fire-resistance compared to plaster.

Despite its many advantages, drywall’s adoption by builders was slow. It wasn’t until the last 50 to 60 years that this material truly earned its recognition. Let’s explore the history of drywall and how it gradually evolved into the widely respected construction material it is today.

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History of Drywall

In 1916, the U.S. Gypsum Company (USG) invented drywall, initially known as "Sackett Board," named after its parent company, the Sackett plaster company [Source: Allen]. Initially sold as small, fire-resistant tiles, the product quickly evolved into multi-layered gypsum sheets with paper backing. Within a few years, drywall took the form we recognize today, consisting of a single layer of compressed gypsum between two sheets of durable paper.

Although it only took a few years for this board to transform into the familiar material we use today, it took builders 25 years before they began adopting drywall on a large scale.

Given all its advantages, why did builders initially hesitate to use drywall? At the time, it was viewed as a cheap alternative, lacking the craftsmanship and elegance associated with plaster. People didn't want to live in homes that seemed poorly constructed, so they continued to favor the traditional and expensive plaster method.

U.S. Gypsum eventually rebranded the material as "Sheetrock" in an effort to improve its image, but it still failed to capture the attention of builders and homeowners.

It wasn't until the United States entered World War II that builders recognized the value of drywall [Source: Gellner]. As the nation focused on wartime production and sent soldiers overseas, there was a critical need for quick, affordable building materials to compensate for the labor shortage and rising war costs. With plaster no longer feasible due to the shortage of workers, drywall became the go-to solution. It allowed houses and factories to be built in a fraction of the time and with far less labor. Cheap and efficient materials were seen as patriotic because they enabled citizens to devote more time and resources to supporting the war effort.

By the time World War II ended in 1945, drywall had become the leading construction material in the United States. During the post-war boom, contractors realized they could build homes and offices ten times faster with drywall than with plaster, leading to greater profits. As time went on, plaster usage dwindled and drywall became the preferred choice globally. In 2007, U.S. Gypsum Company reported over $5 billion in sales, solidifying its position as one of the top producers and innovators of drywall and related products [source: USG].

Next, we’ll explore the process of how drywall is manufactured and how it has evolved since its invention.

How Drywall is Made

Drywall is mainly composed of gypsum, a mineral commonly found in vast deposits resembling white sand. However, impurities can cause the deposits to appear in shades of pink, yellow, or gray. One of the most notable gypsum beds in the U.S. is the White Sands National Monument in New Mexico.

Despite its use in drywall production, gypsum contains a significant amount of water, but it exists in crystalline form, which is why the gypsum molecules remain dry. These water crystals are responsible for the fire-resistant properties of drywall. When exposed to heat, the crystals begin to break down and vaporize as the water reaches its boiling point. The evaporating water helps keep the drywall cool, providing protection to the structure behind it.

After gypsum is extracted from the earth, it is transported to factories around the world. There, raw gypsum is combined with various additives like starch, paper pulp, and an emulsifier (or thickening agent), then mixed with water to create a thick paste. This paste is spread onto Manila paper in layers between 3/8-inch and 3/4-inch thick. Another sheet of Manila paper is placed on top, and the entire formation is passed through ovens, where the sheet is heated to up to 500 degrees Fahrenheit. This process dries the material and prepares it for cutting. Standard sheets typically measure 4x8 feet, though larger sizes like 4x10 feet and 4x12 feet have become more popular due to their efficiency in installing taller walls.

For specialized drywall types, additional additives or unique types of paper are incorporated. To learn more about these variations and how to choose the right type of drywall for your needs, keep reading the next section.

Types of Drywall

While standard drywall works well for most applications, there are various other types designed to meet specific needs. The chart below will guide you in selecting the right type for your project.

After choosing the appropriate type for your project, you'll need to determine how much drywall to buy. Start by measuring the square footage of the walls and ceilings that need coverage. To account for material loss due to cutting and size limitations, add 20 percent to your initial measurement. Then, divide your total square footage by 32 (the standard size of a sheet) to find out how many sheets you'll need to purchase.

Regardless of the type of drywall you use, it’s incomplete without the addition of joint compound, also known as “mud” or “spackle.” This compound is made from a mixture of limestone, emulsifiers, polymers, and water. Its smooth consistency makes it easy to apply, sand, and blend for a seamless finish. Joint compound generally takes around a day to dry, but fast-setting versions are available. Drywall mud is usually applied over fiber-mesh or paper drywall tape, which is used to seal and tighten the seams between drywall sheets.

To learn more about the tools used in drywall installation, let’s take a closer look at how the drywall installation process works.

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DIY Drywall Installation

Installing drywall is a popular do-it-yourself project for homeowners because it’s straightforward and doesn't require costly specialized equipment.

To start installing drywall in your home, refer to the chart in the previous section to choose the right type of drywall for your project. Then, calculate how many sheets you’ll need based on the area’s size. Many home improvement stores offer delivery for your purchases, which is especially helpful given the size of drywall sheets. You can also save money by renting the necessary tools. After acquiring your materials or rental, break your project into three simple steps:

1. Cutting

Start by placing your drywall sheets on a flat, dry surface. Measure the length needed for your project, and use a pencil to mark the cutting lines. With a T-square as a guide, cut along these marks using a drywall saw. You can make most cuts in advance to prepare your materials or cut as you go. The latter approach reduces mistakes and waste but might take longer. A keyhole saw is useful for cutting holes for outlets and switches, while a circle cutter is handy for curved areas.

2. Hanging

Begin attaching your drywall sheets to the wood or metal studs framing your space. For wood studs, hang the sheets horizontally, while vertical installation works better with metal studs. Wood studs are more likely to warp, so horizontal installation ensures better contact with the studs and reduces deflection. Metal studs can be trickier to screw into. When using wood studs, apply drywall adhesive to the studs' faces to further prevent deflection. Secure the drywall with a screw gun and drywall screws, making sure to fasten into the studs every four inches.

3. Finishing

Finally, it's time to tape, sand, and finish the drywall. This process involves applying three layers of joint compound, one layer of drywall tape, and plenty of sanding. Start with a 6-inch finishing knife to spread joint compound along each seam. This initial layer, called the tape coat, should be about four inches wide, centered on the drywall seams. Next, apply drywall tape along the joints, with the mud holding it in place. The second coat, known as the block coat, involves applying more mud over the tape with the same 6-inch knife, just enough to seal the tape. The final coat, or skim coat, is applied using a 10- or 12-inch knife. For this step, be sure to spread the mud thinly away from the seams to achieve a smooth, level finish.

Now, it's time to wait. Allow 24 hours for the mud to dry before you begin sanding.

Use a pole sander with 120-grit sandpaper to gently sand the mud you applied earlier. You're finished when you can't see any tape or mud bulges on the wall, and when a level shows that the surface is smooth and even. Be sure to wear a mask and goggles to protect your eyes and lungs while sanding.

Sometimes drywall gets damaged from impacts. Repairing it is easy: simply fill in any holes, cover with mud, and sand to make it smooth and level with the rest of the wall. For larger holes, cut a piece of drywall that fits the hole, then fill the rest with mud. For smaller holes or dings, you can just use mud. After filling the hole, apply a single coat of mud and sand as usual.

Still unsure about drywall? Check out some alternatives on the following page.

Alternatives to Drywall

While drywall is a versatile material, it does come with some drawbacks. The hollow sound when tapping on drywall can remind people of its lower-cost, quick-installation nature. Additionally, it lacks texture and personality, making it hard to shape or mold. Finally, some believe drywall is too prone to damage.

Fortunately, there are various alternatives to conventional drywall that can be used for creating interior walls in buildings. Let's explore some of these options:

Next, we’ll explore how drywall fits into current green building trends and how both manufacturers and end users can recycle drywall.

Environmental Concerns about Drywall

Sustainable and eco-friendly design is currently at the forefront of the construction industry. Fortunately, drywall is both recyclable and crafted from recycled materials, making it a green choice.

From a manufacturing perspective, drywall is already quite environmentally conscious. The core is composed of 90 to 95 percent recycled materials, primarily reclaimed drywall, while the paper covering is made entirely from 100 percent recycled content, mostly sourced from old newspapers. However, in terms of emissions, the drywall industry still has progress to make. Roughly 1 percent of U.S. energy emissions are generated during drywall production [Source: Sassoon]. In 2008, EcoRock, a product from Serious Materials based in San Jose, was introduced as the first drywall material with zero emissions. Made from almost entirely recycled content, it is said to have no carbon footprint. Builders are showing interest in this innovative material, though its market success will depend on whether customers are willing to pay a premium for its reduced environmental impact.

Drywall waste is fully recyclable, but finding suitable recycling locations can be challenging for consumers. Commercial builders benefit from programs where manufacturers accept scrap drywall for recycling. Homeowners, however, may face more difficulty. While some cities and municipalities have drywall recycling programs, discovering them can require some effort. USG is set to open the world’s largest gypsum recycling plant in Washingtonville, Pennsylvania, in 2008. As green building practices grow in popularity, more recycling channels are expected to emerge.

Recycled drywall has three primary uses. The first and most common use is crushing it to produce new drywall. Many major manufacturers have systems in place for this process. Another use is as an ingredient in Portland cement, which is essential for making stucco, plaster, and other building materials. Additionally, crushed drywall is gaining popularity in agriculture. It serves as a soil conditioner, supplying calcium and sulfur, which benefits crops like peanuts, potatoes, and corn. Recycled drywall can also be used on saline-rich soil to neutralize the ground, making it suitable for planting.

It took some time for the construction industry to fully appreciate drywall's true potential – a versatile, affordable, and sustainable material that has shed its early reputation as a mere cheap substitute for plaster. Today, drywall is something that even the average homeowner can confidently use to build walls. Not bad for a simple solution.

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