When thinking of America's most prosperous time in the post-war building boom, it's easy to overlook the importance of one product – gypsum board – that revolutionized how quickly homes got built. However, if you think it was plasterboard that made that happen, you're right! Gypsum board and plasterboard are one and the same.
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What Is Gypsum Board?
Gypsum board is the generic name for the building material composed of gypsum and paper facers. The facing can be a variety of materials today, but it's all still gypsum board at heart.
To make it, gypsum is quarried, crushed and then ground into powder and heated until it undergoes a process called calcining, which happens when 75 percent of its chemically combined water is driven out. Once it's compacted and pressed between paper facers, it's a durable wall surface ready to be painted.
Gypsum plaster has been used since ancient times, but gypsum board is descended from the Sackett board invented in the late 1800s. In 1893, at the Chicago World's Fair, the palace exterior was completed using Sackett's gypsum plaster bound with fiber. Over the next two decades, Sackett's product was refined and by 1916 was a mass-produced and ready-to-finish board for construction, not much different from what is used in 97 percent of homes today.
A Wallboard by Many Other Names
Gypsum board, Gyprock, Sheetrock, plasterboard, wallboard and drywall can make the topic of wall finishing a complicated-sounding one but unnecessarily so since they're all the same thing. They're just terms used differently in various English-speaking nations. Just think of the U.K.'s "aubergine," which sounds so fancy but is still eggplant.
Sheetrock and Gyprock are brand names. "Gypsum board" speaks to the mineral that makes the board possible, and plaster refers to the process that transforms gypsum into a usable building material. Drywall is a reference to how this product is dry and ready for painting right away, unlike its predecessor, plaster and lath.
Before Plasterboard: Plaster and Lath
Until World War II, plaster and lath were the common wall surfacing. This required lath, usually thin, flat strips of wood (but sometimes rock or metal) erected perpendicular to wall joists or studs and a three-coat application of plaster done by hand. It was laborious and time consuming but resulted in a wall surface that was fire resistant, easy to clean and easy to care for. The plaster of old was also often artful, serving as a beautiful record of craftsmen skills of the era.
For homeowners who are renovating historic homes, there can be a strong urge to pull down plaster and lath in favor of modern drywall, but the U.S. Department of the Interior hopes this isn't done. Why? Even with modern products, it is hard to beat plaster and lath for durability and strength. It even suppresses sound better than most contemporary materials.
It can be expensive to restore plaster and lath, but look at the lasting power it has already displayed. Some homeowners find it frustrating to predrill plaster walls for hanging photos or making other improvements, but unlike modern drywall, repairs can be made to save the wall for decades to come. Environmentally, this is wise and helps preserve the architectural record for the future.
How Plasterboard Revolutionized Homebuilding
Before drywall or plasterboard became widely used around the time of World War II, installing plaster and lath was a time-consuming process. Lath needed installing and then not one but three coats of plaster had to go up and then dry completely between each application. Plaster was sold as powder and required mixing, another step in a convoluted process. If the finish was less than perfect, it needed sanding to get the surface the homeowner or builder desired, and only after sanding was done and cleaned off could the painting begin.
Imagine, then, just how amazing it was for builders who first used drywall. A few nails into the studs and some plaster putty to cover cracks, and a room was done in a day or less. As the building boom began with the post-war baby boom, drywall was not just a huge time saver but also an important factor in how America's construction industry became so key to the economy.
It was during World War II that gypsum board became truly popular since the American military glommed onto it as the building product of choice thanks to its fire resistance. By 1945, the military had used approximately 2.5 billion square feet of the product. Within 10 years, nearly 50 percent of new homes constructed were done with wallboard.
Gypsum Board Varieties
While the tried-and-tested classic gypsum board is still popular, today's builder can also choose Type X, an extra-fire-resistant version that has been enhanced with the addition of fibers inside the gypsum core. This product is generally sold in 5/8-inch thickness or greater. It's meant for premises that require fire-rated materials but can be used in any structure, with a heftier price tag.
Another option is soundproof drywall. It is still made with gypsum but is composed of alternating layers that include polymers or glues. It's not cheap, costing approximately four times that of regular drywall, but it has proven to go a long way in soundproofing a room so things like voices and other regular-volume happenstances are dampened or eliminated. It can be well worth the money for a home office or recording studio.
While plasterboard is usually meant to be primed and painted, there is a pre-decorated option as well. These come with decorative, fade-resistant vinyl finishes. With beveled, vinyl-wrapped sides, they're ideal for spaces where décor is intended to be simple and functional with higher people traffic, like in classrooms, offices and retail spaces.
A Guide to Gypsum Board Dimensions
Gypsum board comes in 4-foot-wide panels. Length can vary at 8-, 10-, 12- or 14-feet long. Paper is the most common backing, but aluminum foil backing is available as a vapor barrier where needed. Edges are beveled, rounded, tapered, square or even a tongue-and-groove edge.
These are the typical choices and uses for the various thicknesses:
- 1/4 inch
is a budget-friendly gypsum board commonly used as a base for multi-layer
applications, like improving sound dampening or as a fresh face in
covering existing walls or ceilings in a remodeling.
- 5/16 inch
is a standard thickness used in manufactured housing like trailers or
gypsum boards are often used in double-layer methods with wood framing,
with this layer being the new face for construction repairs or remodeling.
- 1/2-inch-thick gypsum board is typically a single-layer wall and ceiling material for
residential homes or can be used as part of a double-layer system when greater
sound and fire ratings are the goal.
- 5/8 inch
is considered a higher-quality thickness for single-layer and double-layer
wall systems. At this thickness, it is much more rigid, and there is
superior fire and impact resistance.
- 3/4 inch
is used in most of the same applications as 5/8-inch gypsum board but is a
notch better in quality and durability.
- 1-inch-thick gypsum is made only in 24-inch-wide panels and is primarily used in interior partitions, shaft walls, stairwells, area separation walls and corridor ceilings.
- National Park Service: Repairing Historic Flat Plaster Walls and Ceilings
- Gypsum Association: Using Gypsum Board for Walls and Ceilings Section I
- How Products Are Made: Drywall
- Panel Built: Choosing Wall Types: Gypsum Board Benefits
- Diffen: Drywall vs. Sheetrock
- American Gypsum: FIREBLOC Type X Gypsum Board
- Gypsum Association: Gypsum Board Key Facts