Crawl Space Mold and Moisture Problems

Building mold has emerged as a major issue for the entire home building industry. The issue stems from thousands of insurance claims and lawsuits, including successful multi-million dollar settlements that identify building mold as a health problem for tenants and homeowners. Crawl spaces fitted with traditional foundation vents (wall vented) are particularly vulnerable to moisture and mold problems. Typical problems found in wall vented crawl spaces include:

  • „ Standing water on top of plastic ground cover
  • „ Water condensation droplets on cold water pipes and ductwork
  • „ Muddy soil
  • „ Stained walls from water penetration and efflorescence
  • „ Wet floor batt insulation and or fallen batts
  • „ Visible mold blooms

Ongoing dampness encourages mold blooms to grow in crawl spaces. Crawl space mold readily grows on the wood joists, sills, support beams and subflooring. Generally, these are surface molds (common crawl space molds include Aspergillus, Penicillium and Cladosporium). Mold coverage ranges from light spotting to thick mold blooms that cover large surface areas. Crawl spaces in the west, particularly in Sonoma and Marin counties are most prone to surface mold problems. This is because during rainy  weather, wall vented crawl spaces often stay damp due to moisture infiltration from poor grading and drainage. When this happens, the excess moisture encourages mold to grow on the wood and on any other organic material such as cardboard, dust and paper-faced sheetrock.