By Jim Schneider
Water, like all the elements, can be a great ally—but it can also be a devastating foe, as Superstorm Sandy and other destructive hurricanes have proved. The damage they cause to property and infrastructure is almost incalculable, to say nothing of the lives of individuals impacted by these powerful storms.
Not all buildings will face a storm of that magnitude, but every structure is engaged in its own struggle with the elements. The kind of damage water can cause doesn’t only come from big, headline-grabbing storm events. Dealing properly with water and moisture within the building envelope is vital to the long-term health of the structure and its inhabitants.
"If water comes through the wall and into the building, it’s pretty obvious that needs to be fixed," says Keith Boyer, PE, vice president of architectural wall technology with CENTRIA in Moon Township, Pa. "But probably the more important water issue is when water gets into the system, becomes entrapped, and no one knows it. By the time you find out about it, there can be corrosion, mold, rot, or delamination. A lot of bad things can happen from entrapped moisture."
The types of damage that can occur as a result of trapped moisture vary, but all share one thing in common: they should be avoided. "If you’re dealing with a composite wall where you have materials bonded together, moisture can cause delamination of bonded materials," Boyer says. "The presence of moisture can cause the product to degrade. If you have a multiple component system where you have a lot of different materials, some materials may hold water—like glass fiber or paper-faced gypsum, for example. When those materials get wet, they can retain water, and when that happens you run into some of the mold and other moisture issues that come with retained water."
Mold has been shown to have a very negative impact on indoor air quality and threatens the health and safety of building occupants. But that is just one of the problems trapped moisture can cause. It can damage the building’s structure, as well. "If you have moisture that is entrapped against metal elements like studs, even though they’re galvanized, in the long run they can be corroded," Boyer warns.
So whether water quickly enters the envelope during a mega-storm or slowly seeps through over years of condensation and vapor penetration, the end result can be troubling. "You can potentially have some structural issues, not only with localized fastener pullout, but also with the spanning capacity of the product to take the overall wind loads of the building," Boyer says. "So there are a lot of potential bad consequences that can result from entrapped moisture."
Since moisture is quite literally everywhere, it isn’t possible to keep it entirely out of the wall assembly. The goal is to create an environment in which the moisture that does develop has a way to safely escape. Water can enter a wall system in a couple of ways. Perhaps the most obvious is through precipitation, such as rainfall and snowfall.
Diffusion is another way that moisture can enter a wall assembly. Vapor retarders are often used to slow or minimize this effect. However, if the wall system isn’t designed or built to the right specifications, condensation can occur. This can be particularly challenging in certain climates, and there is often little room for error when putting together the wall’s components. This is where an engineered, pre-assembled insulated metal wall system can ease the work of both the design and construction teams.
Insulated metal composite panels have a sandwich-type design with metal facers surrounding a closed-cell insulation core. They are sealed to create a continuous barrier, and the materials used are not conducive to water retention. Metal is impervious to vapor diffusion. And closed-cell insulation has a much denser and more compact structure than most other insulation materials and functions well in air and vapor barrier designs. It is nonporous and doesn’t allow moisture to become entrapped.
Nature is relentless. For as long as the human race has been building, the greatest challenge has been to create a stable interior environment and keep unwanted natural forces out. We expect our buildings to protect us from the elements. That means shielding occupants from rain, snow, wind, and temperature, of course, but that also means protecting the building itself from subtler—but equally destructive—forces such as condensation and vapor penetration.
With proper wall design, these forces can be kept at bay and the building can create a healthy, comfortable, and safe environment for decades. There are several ways to achieve proper protection from moisture, but insulated composite metal panels provide a single-component solution that can deliver peace of mind to designers and owners alike.
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