The Finish Line
The 'M Word'
If you're involved to any degree with EIFS, you've probably heard stories about forensic studies being performed on EIFS-clad walls that uncovered mold and mildew in the wall cavity. At the risk of being cute, for purposes of this column, I'll call mold and mildew collectively the "M Word."
The M Word is not unique to EIFS; it has occurred on buildings with all sorts of claddings. It is also not unique to damp areas (like my drizzly hometown of Seattle), but has occurred even in warm, dry areas like southern California. This month's column will give you some basic insight into what appears to be a new area of considerable interest in the exterior wall industry.
What are mold and mildew? Actually, they are not the same thing, but are similar. Both are the result of the growth of microscopic living entities, and are a form of fungus. They tend to grow on the surface of organic materials (like wood); they use the wood as "food." They are unusual in that they can go into a dormant state if nearby conditions are unfavorable, such as when it's too hot or too dry. But then when conditions return to normal, they can come back to life. This makes getting rid of them difficult. They are also difficult to remove because they can spread within a wall cavity and do not lend themselves to be rubbed off or "gassed."
M and m's don't make friendsMold and mildew favor warm, moist conditions. However, too moist and too hot is no good, nor is too dry and too cold. A warm, damp wall cavity can make a nice home for these pesky devils. The external location of the insulation in an EIFS-clad wall makes the stud cavity warmer than in normal construction. Most EIFS applications are seamless, too, so there's little air circulation to dry out the cavity. Add a little water, and voila!-a terrarium.
Moisture in cavities can come from lots of sources, including precipitation leaks, leaky pipes and condensation. For example, in warm, humid areas, like the U.S. Gulf Coast, moisture can be deposited in the wall cavity by condensation occurring as water vapor migrates from the outside and comes in contact with the cool, cavity-side face of the drywall. This insidious long-term elevated temperature and humidity condition is not desirable. All it takes are a few miniscule bits of mold and mildew to sneak into the wall during construction, and the seed, so to speak, has been sown.
Sometimes the effects of the presence of mold and mildew are visual: stain on the drywall. Sometimes the presence is nasal: mustiness. Sometimes it's ill health: feeling "not right." Sometimes it's even the building misbehaving: wood studs rotting and the building structure becoming unstable. It's obvious that this matter can have myriad of forms and should not be taken lightly. It is not a nuisance problem (like uptight people getting crazy about invisible color variations of an EIFS finish), but rather it's a real, practical matter.
Mold and mildew can grow on surfaces, like drywall or sheathing, or in things, like fibrous insulation. Getting rid of the M Word is difficult, as they are resistant to simple approaches like sprays. Often the affected material needs to be removed, disposed of and replaced. This can be lots of fun if the studs are wood and have turned to mush: What's holding up the wall if the studs must be removed? It's easy to imagine that getting rid of a mold and mildew in an infested wall can be a huge project. It fact, it gets better .?
Surgeon General's warning: m and m may cause ?Some molds and mildews are said to be dangerous. Complicating the matter is that a given random selection of people will vary in their sensitivity to mold and mildew. For some people it is a serious health hazard, while for other people the effects go unnoticed. Some are even said to be cancer-inducing and have even been likened to asbestos in their insidiousness. I'm not a moldologist, so I can't say for sure if this is true or not, but there are people that think so. I can see the lawyers drooling now.
I believe that this is an area in which a number of construction industry parties need to come together to look into this matter. This includes architects, building material producers, builders and so on. It is not an EIFS issue, but has implications for a wide range of claddings. I suspect that the current energy codes, which foster "tight" construction, contribute to this by reducing the ventilation in the stud cavity, hence affecting cavity temperature and humidity conditions. Sloppy design and construction, as well as building materials that leak, also contribute. In all, it's a complex problem, and it seems to be getting more common.
What can a Walls & Ceilings reader do about the M Word? Doing one's best to keep the cladding from allowing water entry is a start and reminding building owners that EIFS is not 100-percent maintenance free, and that they have a role in keeping the fa?e serviceable is also prudent.
What would I do if I had an EIFS-clad dwelling that was affected by the M Word? I can tell you, because I lived in one. It was a load bearing wood-frame building that had window leaks. The moisture took a heavy toll on the wood, despite the fact that the building was only a few years old, and there were no visible signs of distress until the wall was opened up. The building had to be cacooned for several months to fix it. This was more than I could stand, so I moved on. It's surprising how close the M Word can come to home.