It is rather typical to have a home inspector note that they see “microbial development”. This is their method of easing themselves of liability and keeping in mind that they notice anything that appears like mold, but they aren’t educated or certified to pinpoint it. Most of the time, it is in fact mold development of some sort. In attics, the most typical causes we find are either improper restroom ducting or some absence of or disturbance in the attic ventilation system.

These both have very particular reasons for being built into a houses design. If done improperly, they can trigger significant disturbance of air circulation, triggering moisture build up and condensation on the sheathing giving mold the perfect environment. In crawlspaces typically the reason is more obvious. A lot of houses specifically in the Northwest are built on a foundation.

With as much wetness as we get here, the ground is always wet. That wetness doesn’t simply stop at our foundations. It is soaked up into the soil of our crawlspaces. This is why we have vapor barriers. However if there is excessive ground water, it can trigger puddles of water to form in your crawl space. This water simply sits there and when your crawl space is warmer than the ground itself, the water vaporizes up and now is in the air in the form of humidity.

Now when that gets soaked up into joists, or insulation it is perfect for mold to grow. The other sleeping giant contributing to mold in crawl spaces is the vapor barrier itself. Although it has a job to do in restricting the wetness from rising into you home, it keeps a nice healthy layer of wetness caught underneath which is also a perfect spot for mold top grow.

Why are these problems? “We don’t live in these areas.” Well, no but we have electrical and plumbing in addition to lighting and ducting that runs through our crawlspaces and attics. In minute amounts gradually, we have air that permeate the indoor air of our houses due to variations of atmospheric pressure and temperatures in these locations. Gradually gradually, mold spores being microscopic, can make their {way in| drift in and build up. Simply awaiting a moist location to eventually settle in and begin to grow.