BackPage Primer from Environmental Building News
June 1, 2007
Drywall Options:
Paper-Faced, Monolithic, or Fiberglass-Faced?
Drywall comes in three primary product types. Paper-faced drywall remains by far the dominant product for finishing interior walls. It is inexpensive and easy to work with (cutting panels by scoring and snapping). Environmentally, the paper is typically 100% post-consumer recycled, the gypsum core can be derived from flue-gas-desulfurization (FGD) gypsum (a byproduct from stack scrubbers on coal-fired power plants), and unpainted scrap can be recycled or ground up for use as a soil amendment. The downside is that paper-faced drywall is highly vulnerable to moisture damage and mold growth. Some paper-faced drywall products have mold-inhibiting chemicals to reduce this problem, but it is still a major concern. While FGD gypsum is a waste product and generally considered a good thing from an environmental standpoint, relatively little testing has been done on potential toxins and whether those could be released into buildings—or into the soil if scraps are ground and used as a soil amendment. FGD gypsum is only available in certain regions, and shipping FGD drywall long distances creates more pollution than it solves.
Monolithic drywall, such as USG Corporation’s Fiberock product family, has cellulose fibers uniformly dispersed throughout the gypsum matrix. This makes the drywall both more durable and more resistant to mold. Like paper-faced drywall, monolithic drywall can be made from FGD gypsum and recycled cellulose fiber, and scrap can be chipped for use as a soil amendment. Some products are designed for use as tile backer or underlayment. In limited sampling, we found the retail cost of Fiberock drywall to be more than twice (230%) that of standard paper-faced drywall.
Fiberglass-faced drywall, such as G-P Gypsum Corporation’s Dens line of paperless gypsum panels (DensArmor Plus and DensShield), uses moisture-resistant fiberglass as the facing instead of paper. This category of products is often used as exterior sheathing but is also finding increased application for interior walls in mold-prone areas. It offers excellent mold resistance—even better than monolithic drywall because it has no cellulose to support biological growth. The downsides to fiberglass-faced drywall are that, at least currently, it cannot be recycled, and the fiberglass content precludes grinding for use as a soil amendment. We found the retail cost of DensArmor Plus fiberglass-faced drywall to be about 70% more than that of standard paper-faced drywall.
So, which to choose? In standard interior applications, where there is very little chance of moisture exposure or physical abuse, standard paper-faced drywall remains a fine choice. In basements or in regions where flooding is possible (even above 100-year flood zones) and in applications where greater durability or resistance to abuse is needed (such as in institutional buildings), monolithic drywall is better. Where moisture exposure is anticipated, such as basements and locations where flood damage is likely, fiberglass-faced drywall, or a cementitious panel alternative, is probably the best choice.
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