Is mold a challenge for contractors today? To find out, ask someone with a bit of experience.
Beta Drywall, based in Coconut Grove, Fla., installs drywall for six out of 10 of the largest U.S. builders; twice in the past six years, this company has been the single largest purchaser of drywall in the country. With this tropical base, Roberto Lasorsa, vice president and director of field operations for Beta, has had extensive experience with the subject.
“Mold loves damp and dark, and Florida is damp. When you close a wall up, it is dark,” Lasorsa relates. “Mold needs something to eat too, and normal drywall paper face is a perfect substance for it to survive on. On standard drywall, mold can grow evenly, and it can encase a whole house.”
To combat mold, Lasorsa recommends using mold-resistant gypsum products in all areas with extra moisture and humidity, such as kitchens, bathrooms and basements. In his expert opinion, the benefits far outweigh the additional costs.
“These are wonderful products. They are heavier than normal drywall but just as easy to use, and they finish beautifully. Some do have more fiber but you have to give up something to get something. It slows work down minimally,” Lasorsa notes. “I have ripped out tons of mold and put in this board. I have also seen situations where the mold-resistant boards have gotten wet, and we need to go in and replace the baseboards and flooring but not the drywall. Some of our biggest clients, including Lennar Homes, require it.”
New Board, Less Mold
Most contractors will use mold-resistant gypsum—often called green board—in wet and humid areas. Some contractors like Lasorsa install it on the interior of all exterior walls as well. In Florida most of the houses are built with masonry or concrete, which are not waterproof materials. “Driving rain can hit the block and get pushed into the interior,” Lasorsa says. “If water gets through grout, it will wick and suck up into the walls.”
Nationally, many contractors find mold has become a bigger issue because houses are more tightly built; better for heating and air conditioning, but also a haven for mold.
Gypsum board producers have created several products to help builders protect structures from this literally growing menace.
Scott Carlsen, manager of technical marketing at National Gypsum in Charlotte, N.C., points out two basic technologies behind today’s mold-resistant drywall. National Gypsum and Chicago-based USG Corp. implement an “active” manufacturing process, while Atlanta-based Georgia-Pacific Gypsum employs a “passive” process. “Active” means an antimicrobial agent is integrated into the product. National’s XP wallboard uses a mold inhibitor bonded to the paper fibers in each of the product’s eight layers as well as its core. In the passive process, there is no paper face for the mold to feed on. Instead, gypsum boards are wrapped in fiberglass, which is not a food source for mold.
Both technologies are highly effective in deterring mold, with all three companies’ products scoring a perfect 10 on ASTM D3273, the standard test method quantifying resistance to mold and mildew growth on interior surfaces. Better yet, mold-resistant drywall from all three companies requires no special tools or steps to install when compared to standard gypsum panels. Georgia-Pacific recommends using eye protection, a dust mask and gloves to protect against fiberglass particles while handling its product.
Manage Moisture, Not Mold
However, no material is moldproof. Morrie Newell, spokesperson for the Responsible Solutions to Mold Coalition, a Chicago-based trade group, notes that under the right conditions, mold will grow on anything—including fiberglass—and that mold-resistant gypsum panels are only beneficial if they are properly stored and installed. “No product can substitute for good design and good building practices. Keeping building materials dry before installation is key, and expert scheduling of trades is critical,” says Newell, adding that proper sequencing is important to mold control. “Installing drywall before the roof is on has to be avoided at all costs.
“If people would just do things properly the first time—install proper flashings, for example—I estimate the mold problem could be cut almost in half,” Newell adds. “The business of keeping moisture out of buildings is attention to detail, simple steps are all that is needed—not grandiose strategies.”
John Pappas, USG product marketing manager, agrees that the best long-term approach to mold resistance is managing moisture in the first place. USG has been developing products to help combat moisture infiltration since 2001. Their newest product line under their Sheetrock brand name is Mold Tough. It actively inhibits mold growth on the surface paper, both back and front, and in the gypsum core. “The nice part about the product is that it does handle and finish as normal drywall would,” says Pappas.
A consistent theme from manufacturers, however, is that there is no “silver bullet” when it comes to mold. “We have good technology available,” says Pappas, “but what it really comes down to is managing leaks and problems right when they happen.”