Mold and mildew growth have become a hot-button issue lately due to health concerns. Mold remediation companies deal with eliminating mold/mildew, but it's always best to prevent mold before it starts. One potential weapon in the mold-prevention arsenal is mold-resistant drywall, a product marketed aggressively by manufacturers. When installed in homes, it is often touted by real estate professionals as a selling feature.
Preventing Mold Growth on Drywall
To grow, mold spores require oxygen, moisture, and an organic food source. In the case of gypsum wallboard, that organic material is found in the paper facing on the drywall panels (the gypsum core is non-organic and not subject to mold). Preventing mold growth on drywall can be approached via two strategies:
- Deny mold spores the required air and moisture. With some mold-resistant drywall, this is accomplished by using a thicker paper facing and backing that is heavily saturated with a waxy substance that prevents moisture and air from getting at the paper. Without this, mold spores can not take root.
- Use a material other than paper for the outer layer on the drywall panels. This form of mold-resistant drywall typically uses fiberglass mesh instead of paper for the facing and backing. Because fiberglass is a non-organic material, mold has no food source necessary to colonize for it to colonize.
Increasingly, mold-resistant drywall is also marketed as moisture-resistant wallboard, and where manufacturers once offered two different drywall products—one for mold resistance, one for water-resistance—most products now incorporate both merits. It is important to note that manufacturers never guarantees their product as being immune to mold—only resistant to it.
Good resistance to moisture as well as mold
Easy to repair
Notably more expensive
Mold prevention is not guaranteed
Mold-Resistant Drywall Cost
Modern mold-resistant drywall that also includes moisture-resistance is about 50 percent more expensive than standard drywall. Big box home improvement centers sell a sheet of 1/2-inch, 4 x 8-foot standard drywall for about $12 per sheet, while a comparable sheet of good mold-resistant drywall costs about $16. Buying in bulk will notably reduce this price.
Maintenance and Repair
Like any form of drywall, the mold-resistant form is generally a very durable, easy-to-care-for wall surface. Painted surfaces should be kept clean and should be repainted periodically to preserve a good moisture barrier. All drywall is a fairly brittle material that can be cracked and damaged, but repairs are fairly easy to make, either by taping and refinishing the damaged area with taping compound or by cutting damaged areas away and installing a drywall patch.
Drywall is a ubiquitous material that is a common wall surface in both basic homes and in luxury construction. It is the standard wall finish material used throughout the construction industry. Drywall can accept surface finishes of paint, wallpaper, or textured skim-coat plaster. It should not be used as a replacement for cement board as a backing material for ceramic tile.
Mold-Resistant Drywall Installation
Installation for mold-resistant drywall is identical to that for standard drywall. Panels of drywall are nailed or screwed to the bare framing, then the joints between panels are covered with drywall tape and finished with several coats of taping compound, which are lightly sanded between coats. Baseboards and other trim are generally nailed in place after the drywall is installed. Once complete, the surface is ready for painting or another finish. Since mold-resistant drywall is generally installed in humid locations, the best surface finish is with wall primer and paint that have good mildew and mold resistance.
Top Brands of Mold-Resistant Drywall
The major brands include:
- Mold Tough, from USG
- Gold Bond XP, from National Gypsum Company
- M-Bloc, from American Gypsum
- ToughRock, from Georgia Pacific
Note that these products all combine mold-resistance with the moisture resistance that was once the virtue of green board drywall.
Mold-Resistant Drywall vs. Green Board
Green board is a paper-backed, water-resistant drywall that has a light green "hospital" tint. It is an older form of water-resistant drywall that is gradually being phased out in favor of products that combine both moisture resistance and mold resistance. Green board is intended for use for ordinary wall applications in areas that experience constant high humidity, such as bathrooms and basements, but it does not have the superior mold-resistance of newer products. Green board features a thicker paper backing that has been treated with wax to give it extra resistance to moisture. Huge quantities of this product are still being sold, but don't use it if your principal goal is mold prevention.
Is Mold-Resistant Drywall Right for You?
Modern mold-resistant drywall combines the moisture resistance of older green board with materials and engineering that also make it quite resistant to mold. But these products are by no means waterproof or moldproof—and the manufacturers do not claim so. In normally dry locations, the substantial extra cost of this product is probably not worth the investment. Nor will it prevent mold in the case of flooding, when water saturates the drywall and the organic wood framing behind it. But in rooms that experience frequent humidity and are often subject to mold and mildew, such as bathrooms or basements, mold-resistant drywall is a good choice.