A Guide to Gypsum Wallboard

Drywall is a construction material used to create walls and ceilings. It’s also used to create many design features, including eaves, arches and other architectural specialties. It’s quick and easy to install, incredibly durable, and requires only simple repairs when damaged. In the commercial building world, drywall is used to wrap columns to conceal steel beams and is an easy and inexpensive way to top off masonry walls above ceilings. Drywall is also used to add fire resistance at walls and ceilings, containing the spread of fire so people can evacuate safely during an emergency.

Before drywall became widely used, building interiors were made of plaster. For hundreds of years, walls and ceilings have been constructed by placing layers of wet plaster over thousands of wooden strips called laths. The wet plaster would eventually harden to form walls, but the installation and repair processes were both time-consuming and difficult to do well. Creating plaster walls required several coats to be applied, with a long drying time in between each coat. In addition to its extended installation period, plaster application was quite labor-intensive, requiring skilled craftsmen who labored over a small area of a wall for weeks on end.

Walls that would take weeks to create with plaster could be finished in a couple of days with drywall and would last longer and cost less to build. Damaged drywall can be patched up in a quicker and easier fashion than plaster, and drywall also has a greater degree of fire-resistance.

Despite all these benefits, the use of drywall was slow to catch on with builders. It was only in the past 50 or 60 years that this material truly gained any respect. Let’s take a look at the history of drywall and see how its reputation evolved over the years to become a universally favored building material.­
History of Drywall
The U.S. Gypsum Company (USG) invented drywall in 1916. It was originally called “Sackett Board,” after the Sackett plaster company, a USG subsidiary [Source: Allen]. The material was first sold in the form of small, fireproof tiles, but within a few years, it was sold in multi-layer gypsum and paper sheets. In less then a decade, it took on the form we know, consisting of a single layer of compressed gypsum sandwiched between two sheets of heavy paper.
While it only took a few years for this board to evolve into the material we know today, it took 25 years for builders to begin using drywall in any substantial quantity.

With all its uses and benefits, why were builders hesitant to use something as simple as drywall? At the time, drywall was thought of as a cheap fix, with none of the fine art associated with making plaster. People didn’t want to live in homes that were shoddily constructed, so they stuck with the tradition and expense of plaster.
U.S. Gypsum eventually changed the brand name of the material to “Sheetrock” in an attempt to improve drywall’s reputation, but builders and homeowners still paid no attention.

It wasn’t until the United States became involved in World War II that builders came around to the benefits of using drywall. As the country’s labor force became focused on war manufacturing and many soldiers were sent overseas to fight, quick and inexpensive building materials were needed to offset the labor shortage and war costs. Because the labor shortage was too intense for plastering to remain a viable building option, people began to use drywall instead. Houses and factories could be constructed in a fraction of the time and with a fraction of the labor previously required. Cheap and efficient products were seen as patriotic because they allowed citizens to spend more time and money supporting the war effort.

By the time the war ended in 1945, drywall had become the dominant building material in the United States. During the post-war building boom, contractors knew they could construct homes and workplaces in one-tenth the time if they abandoned plaster for drywall, leading to higher profits. Over time, the use of plaster gradually faded as people all over the world turned to drywall. With net sales of over $5 billion in 2007, the U.S. Gypsum Company is still one of the world’s top producers and innovators of drywall and related products.

What’s in a Name?
The name “drywall” refers to the fact that walls made of the material are installed without the use of water. A major problem with plaster had been the extremely long drying time associated with it, as it was installed wet, and installers had to wait for the previous layer to dry before installing the next one. The word “gypsum” comes from the Latin term “gypsos,” meaning “plaster.”

How Drywall is Made
Drywall is made primarily of gypsum. Gypsum is a mineral usually found in massive beds that look like white sand, though impurities can cause beds to appear pink, yellow or gray. One of the most famous gypsum beds in the United States is the popular White Sands National Monument in New Mexico.

Despite being used to make drywall, there’s a large amount of water in gypsum. The water is in crystalline form, which is why the individual molecules of gypsum are dry. These crystalline water molecules give finished drywall its fire-resistance. As drywall gets hot, the water crystals begin to destabilize and begin vaporizing as the water reaches its boiling point. The evaporating water crystals keep the drywall cool, protecting the structure behind it.
Once gypsum has been mined, it’s transported to factories throughout the world. There, raw gypsum is mixed with several additives, including starch, paper pulp and an emulsifier (or thickening agent), then blended with water to form a thick paste. The gypsum paste is spread onto Manila paper in 3/8-inch to 3/4-inch-thick layers. Another sheet of Manila paper is then laid on top. The entire formation passes through ovens that heat the sheet at temperatures up to 500 degrees Fahrenheit. This dries the material out and prepares it for cutting. Typical sheets are 4×8 feet, though 4×10 feet and 4×12 feet sheets have become popular recently, as they allow for faster installation of taller walls.

Recent Trends in Drywall
The newest drywall types being introduced are being marketed as eco-friendly in order to take advantage of the growing market for green products. In 2008, Serious Materials, a company based in San Jose, Calif., introduced a material called EcoRock said to have a zero carbon footprint. Enviroboard, a drywall-type sheet made of agricultural products like wheat, grass and straw compressed between two sheets of paper, also made its debut in 2008. Both of these materials share drywall’s fire resistance.

Alternatives to Drywall
• Traditional Plaster – Some homeowners still prefer the look and texture of traditional plaster installed over a wooden lath system. Improvements in technology have simplified the installation of plaster a bit over the years, with faster drying times and better structural backing. Certain types of homes, such as those going for a traditional countryside look, will benefit from plaster walls.
• Veneer Plaster – This is an up-and-coming finishing technique that continues to gain popularity. It consists of a layer of thin drywall, called blue board, with a very thin, 1/8-inch layer of plaster applied on top. It’s even faster to install than drywall because no finishing is required. This system is still at least 25 percent more expensive than drywall, so time will tell how eventual price decreases affect its use and popularity.
• Wood Paneling – This material has evolved from the cheesy form it took at its debut. It’s now very easy to install and comes in nearly any wood veneer or finish you desire, though it’s still more expensive than drywall.

Environmental Concerns about Drywall
Nothing’s hotter in construction these days than sustainable, environmentally friendly design. Fortunately, drywall is easy to recycle and is made of green and recycled materials. From a manufacturing standpoint, drywall is already pretty eco-friendly. The cores are made from 90 to 95 percent recycled material, mostly reclaimed drywall, while the paper exterior is made exclusively from 100 percent recycled content, mostly old newspapers. From an emissions standpoint, however, the drywall industry still has a way to go. Approximately 1 percent of U.S. energy emissions come from the production of drywall. A product called EcoRock, introduced in 2008 by San Jose-based Serious Materials, is said to be the first zero emissions drywall material on the market. Essentially, it has no carbon footprint and is still made from nearly 100 percent recycled content. Builders are showing interest in this product, but time will tell if people will be willing to pay a premium for reduced carbon emissions.

­For the consumer, drywall waste is 100% recyclable, but finding places to recycle drywall can be tricky. With commercial use, manufacturers have programs in place so builders can return scrap drywall to be recycled. For homeowners, recycling drywall is a bit more difficult. Many cities and municipalities have drywall recycling programs in place, but finding them may require a bit of research. USG is scheduled to open a gypsum recycling plant in Washingtonville, Pennsylvania in 2008. This plant will be the largest of its kind in the world, and as green building continues to grow in popularity, additional channels for recycling will become available.

Recycled drywall has three major uses. The first is to crush the material and use it to make new drywall. This is currently the most popular choice by far, and all of the major manufacturers have systems in place to do so. Recycled drywall can also be used an an ingredient in Portland cement, which is used to make stucco, plaster, and other building materials. Finally, crushed drywall is growing in popularity in the agricultural world. It is useful as a soil conditioner, providing calcium and sulfur for plants, which is especially useful when growing peanuts, potatoes, or corn. Recycled drywall can also be placed on soil that has a high salt content to help neutralize the ground so that crops can eventually grow there.

It took some time for the building industry to recognize drywall for what it is – an extremely versatile, inexpensive and sustainable material that has overcome its initial reputation as a cheap substitute for plaster to become something an average person could use to build walls.

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