October 9, 2003

Precautions during construction will save headaches later

Photo courtesy of Prezant Associates White mold patches are shown on a joist inside the crawlspace of a building under construction. Contractors shouldn’t attempt to cover up such patches with lumber or Sheetrock, since wet materials will transfer the damage to the covering materials.

Mold and dry rot concerns have been getting a lot of attention lately, most likely because of several legal cases in which millions of dollars have been awarded because of mold infestation in new construction. But is the mold problem really a new one?

Mold has been a problem for builders since pre-biblical times. Over the millennia, however, the more-successful builders employed a few simple techniques that dramatically reduced the risk of mold in their buildings.

Is it possible that in attempting to build more “efficiently,” and by adhering to unrealistic construction schedules, mold is getting the better of us?

Stay dry

Molds are microscopic organisms that are present virtually everywhere in our environment. Molds break down dead organic materials, such as wood and leaves, and recycle nutrients back into the environment. All that is necessary for mold growth to start on these materials is moisture.

Generally, within 48 hours after getting wet, invisible mold growth has started on wet woods and paper-backed products such as Sheetrock. After about four days, mold growth on surfaces is visible in the form of discoloration, frequently green, gray, brown or black, but also white and other colors.

Because molds digest organic material, they gradually destroy whatever they grow on. Molds also release countless tiny, lightweight spores, which travel through the air. Mold spores primarily cause health problems when people inhale very large numbers of them.

In finished construction, roof and window leaks, plumbing defects, drainage and grading problems, and other sources of water infiltration can trigger the chain of events that ultimately leads to active mold growth.

But in a building that is under construction, what steps can be taken to prevent mold growth?

Preventing mold

Our simple advice is this: Do not build with wet materials. While the Pacific Northwest climate may not lend itself to following this advice easily, there are still several steps a prudent contractor can take to prevent or minimize mold growth.

Because we have seen every one of these precautions violated at one time or another, we feel the contractor community might benefit from the lessons that others have painfully learned: