Mishko Teodorovich is a homebuilder and a construction consultant in Austin, Texas, who specializes in mold–resistant construction. He received his Master’s Degree in Engineering from The University of Vermont in Burlington, and is an instructor for construction– and mold–related courses at Texas Tech University in Lubbock, Texas. He has served as an expert witness in construction defect and mold litigations. Mr. Teodorovich is available via e–mail [mishko@mishko.com].

When we talk about mold, we need to see the big picture in order to have the right mindset to understand the issue. In perspective, mold exists to decompose cellulose and other organic materials. Without mold, the Earth would covered with dead bodies, dead trees, and dead plants. If we build homes and buildings with materials that are destined to decay, what will happen with our homes? Materials and methods used in the post–WWII era, particularly after the energy/oil crisis of the 1970s, are likely to accelerate this decay.

Mold growth in homes is supported by "mold food" and water. All cellulose–based building materials, such as drywall faced paper, cellulose insulation, plywood and particle board, represent mold food. This is especially true for recycled cellulose such as recycled paper, which comes potentially with the mold spores already in the product. Keeping the water, in the form of liquid, moisture or vapor, out of the building materials is very expensive and, for many applications, impossible to guarantee.

Nevertheless, the idea that a home or other structure could be built to be more mold–resistant is very attractive and possible. The question is, what does it mean for a building material to be "mold–resistant"? To define a mold–resistant material, the material should be evaluated in terms of both its properties and how it will be used.

Is the material mold food?

To be considered mold–resistant, the material, in itself, should not be a mold food. In other words, mold should not be able to colonize on the material even when material is wet.

Soft, porous materials like cloth, upholstery, canvas and carpet can absorb cellulose dust, dead human skin and construction cellulose–based dust, all of which can serve as foundations for mold growth when wet.

Will the material promote mold growth on other materials?

The material should not be able to cause mold growth on other materials. For example, if an impermeable membrane such as glass or vinyl wallpaper develops condensation on its surface and is placed in such a way that the condensed water can reach a cellulose–based product, mold can colonize. Also, impermeable or even semi–permeable materials can sometimes entrap moisture that would otherwise be allowed to dissipate.

Improper use can disqualify most building materials from being considered mold–resistant. For this reason, proper manufacturer’s recommendations are critical. Frequently, manufacturers of building materials will only focus on the properties of their products and not on the impact that their products could have on the building as a whole. The building needs to be treated as a system, in which different components are impacted by performance of other components. In addition, different climate zones will affect how materials and building components perform and impact each other.

For example, a failure of the water line can cause mold growth on other components of the building. There are ways to detect the water leakage and, if detected, the water can be shut off, avoiding catastrophic damage. Performance failure protection would be very beneficial for a mold–resistant building.

Based on the above, I would define the mold–resistant material to be one that:

1. Cannot be colonized or disintegrated by mold,

2. By its use will not cause mold to grow on other materials, and

3. Will not harbor particles that could be the basis for mold growth.

Even materials that do not meet all three of the conditions listed above can have properties of mold resistance. I would caution here against simply accepting chemical treatment of the materials to make them mold–resistant if the materials’ properties are such that they are not resistant to mold growth without a chemical treatment.

A number of questions arise concerning chemical treatment:

1. Is the chemical treatment safe?

2. Will the chemical treatment only last for limited amount of time then wear off, causing the material to no longer be mold–resistant?

4. Have all possible adverse effects of such treatment been explored?

5. Has the treatment method been field tested and used for an extended period of time, such as 20 years or more?

If the answer to any of these questions is "No," then I would not use that chemically–treated material for vital building components. By vital, I refer to those components for which the replacement cost would be prohibitive or for which failure of performance would cause substantial damage.

One also should take into consideration the expectations that "mold–resistant" products might breed in builders and property owners. In other words, they might think, "I don’t have to worry about the humidity in my finished basement because we installed mold–resistant drywall." To be truly mold–resistant, the home would need to have a proper overall construction and maintenance protocol. The use of one or two mold–resistant products alone is not likely to make a substantial difference in the ability of the structure as a whole to resist mold growth.

The use of such materials in construction projects probably can reduce liability for builders and other groups. Strategically, all industries involved with construction will have to realize that complying with a construction protocol that makes appropriate use of mold–resistant materials, when possible, will benefit everybody. Homes built that way would be much lower risk to own, maintain, insure and finance. There are attempts from builders associations to legislate guidelines for moisture resistance. Some of the guidelines are improvements in the quality of constructions, but none would guarantee a mold–free home.              

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