Mold-Resistive Construction

Headache, stuffy nose, sneezing, coughing — these are symptoms commonly associated with a cold, the flu, allergies and other health problems. Sometimes these symptoms persist beyond an affliction’s normal timeframe. And once in a while, these irritations are found to be caused by a person’s exposure to a particular place for long periods of time.

One looming issue for administrators of public and private buildings is indoor air quality. If our buildings are a factor in their occupants’ health, what can we do to improve the health of our buildings?

One of the major culprits that can affect indoor air quality is mold. Mold is like an imp or gremlin searching for the right circumstance to create trouble. Eliminate the circumstances and the trouble never occurs. Often times, mold damage can be prevented by eliminating the use of certain building materials.

Molds are microscopic organisms that thrive in warm, damp, poorly ventilated environments, such as shower/toilet areas, storage rooms and wall cavities. Most often, mold is the result of a leaky roof, plumbing leak, overflow from sinks or a damp crawl space. Some building materials inadvertently provide suitable nutrients that encourage mold growth. Cellulose materials, including paper and paper products, cardboard, drywall, wood and wood products, are particularly conducive for the growth of some molds. In fact, mold spores can be found on just about every organic substance. If provided with sufficient moisture, these spores can rapidly disintegrate almost anything organic.

So why has mold suddenly become such a hot topic? The answer is simple. Many structures built throughout the United States from the late 1980s to early 2000 were built with materials that are capable of supporting and of being disintegrated by mold. Buildings that have moisture events, such as a roof leak, wall leak, window leak or plumbing failure, are prime targets for mold. It has already been proven that mold can be unhealthful for students and staff, and there are obvious moral and financial obligations related to those health concerns.

In addition to the health issues, mold has recently been in the news because of its effect on building repair costs. Some facilities must be partially, if not completely, demolished. The greater expenses, however, are often not the repair of the initial leak, but finding out that the mold created by that leak has destroyed the very material that was installed to protect the building — material that includes critical parts of the building envelope.

Realizing There Is a Problem
Unfortunately, the following scenario is played out all too often. Students and teachers in a central Texas middle school began to notice an increase in humid air and musty smells. In addition, the school began to experience a high number of student absences — much higher than other district facilities. Officials had to ask themselves if indoor air quality and mold could be the reason for the problems, and what could be done about it? Consultants brought in to assess the problem found that mold damage had progressed quickly in various areas of the building, partly due to roof leaks and some other moisture problems. Demolition of part of the building envelope was the only solution.

The school superintendent’s response was predictable —“My taxpayers will be paying for this building foranother 25 years and we’re about to tear part of it down? How could this happen and, more importantly, how can we keep this from happening again?” The answers were not reassuring. The school had been built using paper-based gypsum sheathing in the exterior wall assembly. Unfortunately, all interior walls were built with a similar material. Minor plumbing leaks, toilet overflows and splashing sink water had caused mold growth in areas inside the building in addition to the roof-related damages.

Anticipating the Future
This scenario occurs all too often when school leaders learn that a minor leak, undetected for an extended period of time, has grown to be a budget-busting and time-critical repair. The fact is, with a bit of future planning, these problems never need to occur. A simple system, time-tested and proven for strength, durability and cost effectiveness exists. The system is called mold-resistive construction (MRC).

MRC was developed based on the concept that buildings should have a life expectancy of at least 50 years, and that it is likely that during that time some type of moisture event — plumbing leak, roof leak or window leak — will occur. MRC construction is designed to be forgiving — it can withstand moisture events that destroy many modern building materials. The key to MRC is simplicity. Using these methods, moisture can be identified and stopped, allowing the building envelope to be dried and cleaned. Demolition never enters into the repair equation. Consequently, the cost for any such repair is less disastrous and, more importantly, of little impact on the daily operation of the building.

So what material is considered in the MRC system? Today, only three categories of material make up the list — concrete masonry, brick and stone. MRC materials, when properly detailed and built, have a proven history of lasting for years with limited maintenance requirements. In addition, mold and other indoor contaminants will not destroy them. If mold is discovered, these materials may be cleaned without the use of harsh chemicals or cleaners that could impact the health of the occupants of the facility.

Following are a few things that should be considered when planning a school construction project.

  • The average wall and roof costs for a school are 19 percent of total cost — a relatively small amount — so invest in a quality envelope.
  • Walls and roofs are the source of most moisture and maintenance issues.
  • Most mold problems occur as a result of a compromised portion of the building envelope.
  • Few school districts can afford to budget major maintenance for exterior school walls.
  • The majority of costs from mold damage are the removal and replacement of material that has been destroyed.

A Proactive Solution
To solve IAQ and mold issues, designers must design buildings with materials that can sustain moisture breaches without catastrophic results. Prevention, rather than repair, is the key to successful building health. MRC provides a level of protection found in no other system. When coupled with proper heating, ventilation and air-conditioning systems, and a proactive rather than reactive maintenance program, school districts can realize a healthier environment for staff and students.

BY CHRISTOPHER HUCKABEE, AIA Huckabee is the CEO of Huckabee Inc., and a member of the National Concrete Masonry Association. He can be reached at .

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