Fighting the Moisture Intruder

David O. Hunt Jr.

May 2007

Wall and ceiilng contractors say the battle against moisture intrusion is won with a quality design, sound construction technique and the proper use of modern building materials.

Mike Poellinger, president and general manager of Poellinger, Inc., of La Crosse, Wis., said basic dehumidification during the construction process is critical to winning the fight. He said wall and ceiling contractors introduce a great deal of moisture into a building solely with the products they use to complete their work.

"We bring a tremendous amount of water into a building,” Poellinger said. "With the amount of wood and other porous material that also gets installed, it is critical that we get that water back out of the building.”

However, Poellinger said some general contractors or building owners seek to push the construction schedule, or may not wish to add to the total contract cost with dehumidification. He said larger construction firms generally understand the importance of dehumidification, but smaller ones may not.

"General contractors aren’t paying attention to water intrusion the way they should,” Poellinger said.

Poellinger said he took notice when several schools in his area had to be temporarily closed because of a combination of factors that included a tight construction schedule, a push to open quickly before materials like sealers and carpet had a chance to "off gas” and a lack of proper dehumidification during construction. In one school, an uncontained wall was opened and examined for black mold. But because the wall was uncontained, the HVAC system spread the mold throughout the school, and 12,000 square feet of exterior wall later had to be removed and the whole school had to be disinfected.

If other parties balk at dehumidification, Poellinger said his firm presents a simple legal document pointing out the dangers of not dehumidifying a building prior to installing walls.

"This is our way of telling the other party that you’re out on your own if you want us to put in the walls without dehumidification,” he said.

Different by Design
In a positive development, Poellinger sees more and engineers cutting down on the opportunity for mold growth through building designs.

"In this area, we see engineers specifying more post and beam designs for light commercial applications, which allows roofs to go on before the side walls,” Poellinger said.

Based in Wisconsin, Poellinger said he also sees more contractors installing panelized walls and roofs, which eliminate some of the variables in of the field.

Poellinger also serves on the board of directors of the Responsible Solutions to Mold Coalition, based in Chicago. The group maintains an informational Web site for consumers and the construction industry on the Internet at

Glenn Strong, president and CEO of Sea Hawk Enterprises of Aptos, Calif., serves as a consultant to architects and general contractors, using research to help them specify the proper use of building materials.

Strong also said sound design and construction practices prevent moisture intrusion.

"If a building is well-designed, constructed with properly installed details and built in the right sequence, it will not leak,” Strong said.

Strong said he currently believes the lack of experienced supervision and labor is taking a toll on construction workmanship. This lack of experience, he said, sometimes shows up as moisture intrusion.

Strong said he has completed forensic inspections on several school projects. He said a lack of workmanship in installing the details served as the culprit.

"We don’t have the same level of craftsmanship and workmanship that we had 20 years ago,” Strong said.

To combat this lack of experience in the field, Strong recommended contractors maintain a solid training program to create quality assurance.

Strong said he frequently specifies smart vapor retarders that "breathe,” preventing moisture from intruding into a wall cavity during the summer months, but also allowing moisture to be expelled during the winter months.

Look Before You Leak
David Chawes, a certified industrial hygienist, recommended inspecting wood and other materials closely before using them.

"Before installing the materials, inspect carefully for water damage, staining, warping or initial signs of mold growth. Such signs might be visible patches of mold, or simply the musty odor we associate with mold or mildew. Discard any such materials immediately,” Chawes said in a published report.

If materials are wet, Chawes suggested using equipment to dry them as quickly as possible.

"If, despite these precautions, mold starts to grow on installed building materials, do not attempt to ‘cover it up’ by installing dry lumber or [wallboard] over it,” Chawes said. "Mold spreads very rapidly in a moist environment, and the wet materials will serve as a moisture source that will rapidly transfer damage to the previously clean, dry materials.”

Finally, Chawes said if moisture gains a presence in a building, seek the advice of a consultant.

"If mold does get a foothold in your building, get expert advice immediately, since the problem could be made worse by transferring spores from affected materials to previously clean areas. Find a consultant experienced in assessing mold growth and an engineer experienced in determining the structural stability of the installed materials,” Chawes said.

Michael Hamilton, vice president of Martin Corp., a wall contractor based in Escondido, Calif., said maintaining the proper sequence of construction cuts down on many moisture-related problems.

Hamilton said common sense dictates that a roof should cover a structure before the walls are installed, a step he said goes a long way in preventing problems.

"Just maintain proper, responsible construction practices,” Hamilton advised. "Also, don’t kid yourself into thinking that moisture problems can’t happen to you.”

Hamilton said he watched several high-rise projects being built several years ago in his area. He said the construction calendar was pushed, and interior walls were constructed before they were covered. Unexpected rain fell that year in Southern California, delivering a damaging blow. Hamilton watched as moisture-laden interior walls had to be pulled out of the structure.

New Products to the Rescue
Hamilton said he is impressed by the performance of the new lines of mold and moisture-resistant wallboard. Martin Holbert, president of Expert Drywall of Redmond, Wash., also said he is a fan of the new wallboard products.

Still, Holbert said some building owners are choosing not to pay the premium for mold-resistant drywall.

That stance may seem confusing, given how quickly moisture problems and resultant mold may develop during the life of a building. The Centers for Disease Control warns homeowners about the potential human health effects of airborne allergens produced by mold. But medical experts say the health impact of those allergens depends on the strength of an individual’s immune system.

High profile lawsuits and news stories on the mold issue have sounded a warning bell to the construction industry and to building owners in general. A survey by CertainTeed in 2005 found 55 percent of 1,000 homeowners expressed concerns about mold.

As part of the effort to combat moisture, wall system manufacturers have introduced lines of mold and moisture resistant wallboard products. However, manufacturers such as National Gypsum insist the new products are only part of the more overarching solution to fighting the moisture intruder, and that proper design and construction practices must be followed during construction to prevent problems.

"Building materials must be protected from exposure to water or moisture during storage and construction. Only by combining sound design, installation, inspection and maintenance practices can this be accomplished,” according to the Web site of National Gypsum, the Unites States’ second largest manufacturer of wallboard, based in Charlotte, N.C.

With that said, David Drummond, marketing director for National Gypsum, suggested overall sales of mold and moisture resistant drywall are picking up.

Drummond emphasized that mold and moisture resistant products have limitations and are not classified as moldproof. While sales data are not available from the privately held company, Drummond said the products are showing "strong sales growth.” He said sales of mold and moisture resistant wallboard have exhibited the strongest growth in coastal areas, the northeast region and California.

Holbert, of Expert Drywall, also said eliminating moisture intrusion requires a combination of factors.

"Obviously, a good design is a preeminent requirement, along with a general contractor to coordinate the work so that all of the details are built and installed properly. Of course we are obligated to install the features according to the design, but that doesn’t mean the wall and ceiling industry shouldn’t review those design features, and suggest changes if they see deficiencies,” Holbert said.

About the Author
David O. Hunt Jr. is a free-lance writer/photographer based in Hershey, Pa.