PATH Report: Building Manufacturers Launch New Mold-Resistant Products

Approximately 55 percent of homeowners express concern about mold, according to a 2005 survey by CertainTeed.

For builders, mold can translate into costly and time-consuming callbacks for remediation, particularly if mold is found in the drywall.

With news about the dangers of mold spreading, innovative manufacturers have launched mold-resistant gypsum products.

These products not only can be good for your homes but can be — if you promote the gypsum board to your customers — a powerful and distinctive marketing strategy as well, particularly in conjunction with aggressive advertising by manufacturers.

"From a consumer awareness point of view, it has been phenomenal," says Leo Bissonnette, manager of Georgia-Pacific's Dens Products. He notes the product does well among do-it-yourselfers, who find it in major stores like Lowe's and Home Depot, and "because of its popularity with consumers, we have seen some more interest from builders. It is creating a bit of a pull-through of the product."

Mold-resistant gypsum is not a substitute for good building practices, however. Proper roof pitch and window flashing; minimal roof penetrations; a well-drained, weather-resistant envelope; and other design elements can reduce the likelihood of moisture penetration, and you should include them. But mold-resistant drywall provides a good layer of extra protection, especially in high-humidity rooms.

Unchecked, mold growth can rot wood and damage drywall. It can even cause structural damage.

But the main concern for homeowners is the health implications.

Molds produce allergens, irritants and, in some cases, potentially toxic substances. Inhaling or touching mold or mold spores may cause allergic reactions and illnesses. Mold can be a serious concern for people with weakened or suppressed immune systems.

"We've seen a real concern about mold from our clients," says Paul Boa, a production manager with Bensonwood Homes in Walpole, N.H. "In terms of selling it to customers, it's been pretty easy."

Bensonwood installs mold-resistant drywall on the interior of the exterior walls of all of its factory-built timber-frame custom homes. Because the preassembled walls can be exposed to the elements, Boa said Bensonwood wanted to provide an extra layer of protection from mold growth. And most of the firm's clients have been excited to see the mold-resistant product.

But mold is such a concern, even the finance industry is weighing in.

"A home with mold loses its value dramatically. For example, a $250,000 home can have $100,000 worth of mold problems. All of a sudden, a lender finds their loan is worth more than the home," says Charlie Perry, president of the Environmental Assurance Group, a consulting firm that addresses mold issues in real-estate.

On behalf of lenders, investors and insurance companies, Perry helps prevent losses from mold-infested homes. But the best-case scenario, he says, is that mold growth never starts.

"Unlike some other environmental issues, there are no good fixes for mold. Once the problem sets in, it is almost always there, and sometimes the remediation is more costly than the house is worth," Perry says.

To highlight the importance of mold prevention, Perry has started design and construction of the Mold Safe Model Home project. Sponsored by the Partnership for Advancing Technology in Housing (PATH), the 3,000-square-foot home in Chesterfield, N.H., will include paperless drywall, vapor barriers, proper water drainage design and other features.

"With mold, it is about prevention, prevention, prevention," he says. "We started the Mold Safe Model Home to demonstrate the value and easy application of mold-resistant products, such as mold-resistant gypsum board."

What exactly is mold-resistant gypsum and how is it different from your usual drywall? Mold requires two elements to grow: moisture and food. For water, a little condensation in a bathroom or around a windowsill can be enough. For food, almost any organic substance will do.

Therefore, gypsum board manufacturers have developed a variety of products that eliminate either food or water.

Several manufacturers, including USG Corp. (Sheetrock's Humitek), National Gypsum Co. (Gold Bond Brand XP), and Temple-Inland (Silent-Guard TS gypsum shaftliner), chemically treat the paper on both sides of the gypsum board. This means the gypsum cores don't absorb moisture as easily.

Another tactic is eliminating the source of food — the paper. Georgia-Pacific (using DensArmor Plus) replaces the paper with glass mat facings, while USG (using FiberRoc AquaTough) uses a paperless gypsum-cellulose combination.

In all cases, the product mounts almost identically to regular gypsum. The dimensions, installation methods and finishing techniques are the same.

Boa says workers have complained about the amount of dust generated during cutting, but Bensonwood has adjusted by cutting the drywall with handsaws.

Mold-resistant does not mean mold-free. The current standard for mold-resistant characteristics of drywall is the ASTM D3273 Standard Test Method for Resistance to Growth of Mold on the Surface of Interior Coatings in an Environmental Chamber. D3273 measures the ability of the drywall to resist mold and mildew growth under prescribed moisture conditions. Several manufacturers measure the performance of their products against this standard.

The products mentioned above achieved ratings between eight and 10, with 10 being the best rating.

It is important to note, however, that materials are tested only for 30 days, so the standard does not address longevity of the mold-resistance treatment.

With both types of mold-resistant gypsum, it's important to keep the material dry and clean on the job site. If not, you will be giving mold a place to thrive, despite the design of the gypsum board.

Like many technological advancements, mold-resistant gypsum comes at a cost premium. The product can cost 30 to 50 percent more than traditional drywall. Georgia-Pacific estimates that a 2,500-square-foot home uses about 10,000 square feet of drywall; if you replaced it all with paperless gypsum, your drywall would cost $1,500 to $2,000 more. At that price, many builders tend to use it just in bathrooms, kitchens, exterior basement walls and other areas where moisture or humidity is high.

But in storm- and flood-prone regions of the country, it may make sense in every room. For example, the Katrina Cottages — the 544 to 936-square-foot home kits sold by Lowe's in the Gulf Coast region — include mold-resistant drywall throughout.

Although the cost of the drywall is higher, compare it to the expense of remediation.