Gypsum Sheathing by Another Name

Calcium sulfate dihydrate is a mouthful. It is all around us, and is an invaluable material to the construction industry. It is made into plastic form, then extruded between thick sheets of various materials and allowed to harden. The basic process was invented in 1888 in the United Kingdom.  

In 1910, the United States adopted and refined the process using calcium sulfate dihydrate. Innovations using this miracle mineral came fast and furious over the next few decades. By the 1980s, it seemed all possible innovations utilizing this mineral had been exhausted and we simply took it for granted. Within the last few years, however, innovation with calcium sulfate dihydrate has been more prominent than ever before. What is this miracle mineral? You know it by the name: gypsum.  

In its basic form, gypsum is strong and fire resistant. Manufacturers found out that adding fibers just added to the already fire-resistant properties. Then additives were discovered to push the limits of what the mineral could do. Today, we add silicon, mildew resisters, and products to reduce water absorption. It is fair to say that today’s gypsum panels are not what your grandfather once hung.

Today’s Sheathing v. Yesterday’s Sheathing

Gypsum sheathing may have been put through the most recent and aggressive innovation process since the beginning of the century. Once upon a time, gypsum sheathing was limited to commercial projects, and used only when a fire rating was needed on an exterior wall. Today, gypsum sheathing comes in various coverings often denoted by the bright color a specific manufacturer selects for their innovation. But make no mistake, these products go far beyond what grandpa thought gypsum sheathing could do. Today’s gypsum sheathing adds a stronger backing strength, enhanced moisture protection, and extended exposure times to the elements.

Traditional gypsum sheathing was a fire-resistant core encased in a brown water-repellant paper on both sides. It was economical but had limitations. For example, the first generation of gypsum sheathing was not to be used on ceilings and soffits. Compare that to today, where most plaster bureaus would recommend and even prefer, these new sheathings for soffits utilizing a polymer skim coat of cement, fiber mesh, and acrylic finish coat. We generally call this a Direct Applied System.

This can confuse architects who call the Stucco Manufacturers Association for advice on a suspended cement plaster ceiling. We talk to them about the need to beef up hanger wire and narrow cold-rolled channel spacing. The conversation then turns to something like, “You know using a DAS would be faster and probably safer without losing the look you want or the fire rating.” In the past, this has bewildered them. How could the cement stucco association say this? Well, because it is true and the new highly improved gypsum sheathings have made it kind of a no-brainer.

The old paper faced gypsum sheathing had another limitation; it was only allowed to be exposed to the elements for up to one month. Today’s new gypsum sheathings can be exposed for more than two seasons. While this may seem not a big advantage at first read, think about project delays and how these sheathings are routinely asked to be exposed to sun, rain, and snow as the cladding is on backorder or stuck in the Port of Long Beach on a container. Thank goodness for these new and incredible gypsum sheathing products. Without them, landfills would be full of discarded paper-faced sheathings, which is detrimental to mother earth.

The innovations do not stop at just exposure and use; waste with sustainability has also been addressed by the gypsum industry. It is reported that 12 percent of all gypsum board ends up as waste. This occurs at the factory and during installation as pieces are cut with remnants tossed aside. In 2016, the gypsum industry toughened up the standards to double down on recycling efforts of waste gypsum.

Continuous Innovation

The gypsum industry has made mistakes, like all industries do from time to time. However, for the most part they are on the cutting edge of innovation and sustainability. While this sounds like I work for the gypsum industry, I do not. I work for the cement plastering industry, but feel that credit is due to my friendly competitors on the other side of the aisle.

Gypsum panels are more American than most other products. Traveling to Europe for almost three decades, I visit project sites and they are fascinated with American practices utilizing gypsum panels. While still fairly entrenched in masonry and plaster walls, more and more American products are making their way into Europe. It can be hard for them to believe these bright colored sheathing products are better than the products they are using. I usually have pictures on my phone of U.S. projects with all the colors of the rainbow to highlight the widespread use across our country. The world is changing fast my friends.