Mold In The Crawl Space

Mold In The Crawl Space

Here in the wet west coast, or in the city I like to refer to as “Raincouver” we are at a considerable disadvantage to dryer areas, so understanding the moisture issues that affect the home is critical.

The No.1 reason for continued mold growth in the crawl space (or anywhere else for that matter) is due to moisture.

Why is mold in the crawl space more problematic than other areas of the home, such as the attic? Accumulated crawl space mold can go undetected for years, negatively affecting the indoor air quality for the people living above. Attic mold, although not desirable mainly for structural reasons, will not likely affect those living in the home below. Air in the attic tends to rise, as does air in the crawlspace. When attic air rises, it escapes. When crawl space air rises, it pollutes the household.

Heath issues associated with prolonged exposure to mold, especially for young children, the elderly and those with respiratory issues is already a large-scale concern.

Crawl spaces with dirt floors are the worst. The earth continually releases litres of vapor moisture into the crawl space. In as little as 24 hours, if the conditions are right, mold can grow and eventually migrate into the home. Moisture seeps from the outside in, through concrete foundation walls.

The following outside conditions can be blamed on moldy crawl spaces:

  • Foundation cracks
  • Poor above and below grade drainage
  • Leaking or overflowing gutters
  • Vegetation against the foundation
  • Conditions favorable to pooling, such as poorly sloped homes
  • Soil beds and sprinkler systems against the foundation wall
  • Homes without water proof membranes or moisture barriers

Other contributing factors to mold growth include storage items of any paper based or organic material. Mold grows on anything organic, especially paper or cardboard. Subsequently, mold destroys not only wood, but also personal documents and cherished photographs. If you must use the crawl space for storage, put these items in dry, sealed plastic bins.

As mentioned above, mold is dangerous to people and animals living in the home. Mold spores travel up into the house through voids caused by heat and plumbing contractors. All gaps between the crawl space and the living quarters should be properly sealed, with insulation, or tuck tape for example. The crawl space access door should be weather-stripped, insulated and tightly sealed.
Typically, crawl spaces are dirty, damp, harbour pests and can be unsafe, which is why most people tend to avoid them… and why I always wear a respirator when I inspect them.

If all crawl spaces were built like basements, they would be tolerable. In fact, crawl spaces should actually be conditioned, or heated like a basement. Contrary to conventional wisdom, they should not be vented. The reason for this is two fold. Vents allow moist cold air into the crawl space during the winter, so the issue is obvious. In the summer the vents allow warm air in. When the newly introduced warm air comes in contact with the cooler materials inside, condensation forms. So, it really doesn’t matter what the weather is like, vents contribute to mold in the crawl space.

If you happen discover a significant mold problem in your crawl space, you will have to call a remediation company. Costs to both your wallet and health can be considerable, so consider the tips in this article. My best advice… keep the crawl space dry, sealed, insulated and warm.

For more information on this topic, take a look at the other mold related articles on my blog or feel free to contact me. Take care and keep your crawl space mold free.