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Green is Good: Understanding Moisture- and Mold-Resistant Gypsum Panels

“Green board” has been around the industry for a few decades now. Building its reputation as a water-resistant option for drywall installation, its green-hued face paper gave the product its namesake, but its original design was limiting.

In time, USG developed a product to improve the shortcomings of “old green board;” a new drywall that prevented moisture from penetrating its face and back papers. Only this time it wasn’t green, but blue. Sheetrock® Brand Humitek® Gypsum Panels, introduced in 2003, were lauded by the Chicago Tribune as “one of the biggest drywall breakthroughs since 1890” for the building industry. With the product’s release, USG provided the industry with a cutting-edge solution for areas of moisture in both residential and commercial spaces.


Breaking the Mold

Rather than rest on their laurels, USG advanced its Humitek® technology with the introduction of Sheetrock® Brand Mold Tough® Panels in 2007. These panels were the first patented wallboards that actively inhibited mold growth on the surface paper, from front to back, as well as moisture resistance in the gypsum core.

Utilizing proprietary technology, ingredients were added during the manufacturing process to protect the wallboard from moisture and mold and adopted the familiar, green-faced appearance of green board with both mold- and water-resistance. As a result of the premium performance of Sheetrock® Brand Mold Tough® Gypsum Panels, this new product consolidated replaced both Sheetrock® Brand Humitek® Gypsum Panels and USG’s water-resistant (green board) product line in its family of industry-leading solutions.

The credentials performance of Mold Tough® technology proved that it was more than your average green board. But there is still a greater discussion of the building science to be had about how buildings surfaces develop materials that attract mold in the first place.


What is ASTM D3273?

ASTM International, which sets the industry standards for testing and evaluation of different performance criteria, provides the framework for understanding degrees of mold resistance performance. 

ASTM D3273 is the standard test used to measure the resistance of wallboard for mold and provides an evaluation of wallboard’s resistance to mold growth.

It is important to note that this ASTM lab test does not accurately represent the mold performance of building materials in the field. Given unsuitable project conditions during storage, installation, or after completion, mold can overwhelm any building material. To manage the growth of mold, the best and most cost-effective strategy is to protect building products from water exposure during storage and installation and after completion of the building. This can be accomplished by using good moisture management design and construction practices.

Control Moisture, Control Mold

Even if your drywall contains moisture- and mold-resistant properties, it can still be at risk for mold growth if not for careful design, proper construction, and thorough maintenance. These factors are meant to manage moisture, which is the only variable that can be controlled within the construction environment. The risk for mold growth can be elevated by:

  • Product storage and installation condition
  • Faster track schedules
  • Poor execution of water control
  • Energy-efficient buildings without moisture management design.
  • Snow and rain exposure during the construction phase
  • Inadequate drying of concrete, plaster, and paint as a building is completed
  • Roof and pipe leaks
  • Excess water penetration of the façade
  • Natural disasters

Adopting a building science and systems approach to managing water has proven to be the most effective strategy for controlling moisture and minimizing the growth of mold. Since mold occurs naturally everywhere in our environment, it is important to know how construction practices can influence moisture management.

Moisture is critical because mold is unable to develop and grow without it. When the risk of moisture exposure is present, be sure to choose products and systems that offer added resistance in conjunction with sound design and construction practices. Limiting moisture during the construction phase allows mold-resistant products to act as extra protection against mold growth when incidental moisture (condensation, steam, or dampness) is present.

In areas with limited moisture exposure, USG Sheetrock® Brand UltraLight Panels Mold Tough® (Regular and Firecode® X) is recommended. Featuring a noncombustible moisture- and mold-resistant core that is encased in moisture- and mold-resistant, 100% recycled green face and brown back papers, these panels protect against incidental wetting and the resulting mold growth, but must be protected from elements before, during, and after construction due to the paper facings.

For areas where extended moisture exposure is present, such as pre-dry-in construction (also known as top-down or fast-track), USG Sheetrock® Brand Glass-Mat Panels Mold Tough® (Regular and Firecode® X) are the ideal solution. These panels feature a noncombustible moisture- and mold-resistant core encased in an inorganic fiberglass mat that sheds water.

An Unrivaled Moisture- and Mold-Resistant Solution

When it comes to controlling moisture and resulting mold growth, it can be hard to separate fact from fiction. But the bottom line is this—mold spores are everywhere, and they can grow on virtually any surface where moisture is present. Consequently, controlling mold growth begins with moisture control through best building practices.

Adding the right protection in the right places is a critical aspect of the equation. And that’s where USG Sheetrock® Brand gypsum panels with Mold Tough® technology really make their mark. These panels come from a comprehensive product line of moisture- and mold-resistant solutions that meet ASTM C1396 specifications. This ensures that our customers have only the highest-performing materials in the fight against mold and moisture.

For more than 100 years, USG has been the leading manufacturer of the highest-performing building materials within the industry. You can trust that when you choose our products, you will get unrivaled quality every time. With such a storied history of innovation, USG has proven that green is still good.

Learn more about USG’s moisture- and mold-resistance here.