General Crawl Space Mitigation Plan

PROBLEM: The excessive moisture in the crawl space has caused mold development.

Inspect the crawl space for the type of mold and the density of mold in spores per m3.

The inspection may include Air Samples and or Bulk mold samples from the joists.

Mold testing kits from Hardware Stores are useless.

The source of the moisture must be stopped or controlled:

  1. Change the landscaping to drain the water away from the foundation.
  2. Change the down spouts to direct water away from the foundation.
  3. A drainage system in the crawl space and a sump may have to be installed.
  4. Personnel will use breathing protection facemasks (NIOSH 95) when in the crawl space.
  5. Install two dehumidifiers with auto drain systems in the crawl space.  Auto drain systems will pump condensate water up out of the crawl space to a drain or outside.  Set them to operate when the moisture level exceeds 50% rH.
  6. Remove all debris from the area (Wood, Paper, Cardboard, Concrete junk, etc).
  7. All debris must be placed in 6 mil plastic bags for removal from the crawl space.
  8. Remove any insulation between the joists and against the ban boards.
  9. Joists and subfloor should be clear of screws, nails and staples.
  10. Level the ground including stones and sharp objects.
  11. Install a Moisture Barrier – Minimum 12 mil plastic sheeting – Maximum 20 mil
  12. See for materials for moisture proofing crawl spaces.


Mitigation Plan for a Crawl Space

  1. Perform all work per the IICRC S520 Standard for Mold Remediation.
  2. Install air scrubbers in the crawl space; the capacity should be adequate to turn the air volume in the area five times per hour.
  3. Isolate the 1st floor from the crawl space to limit air flow between the two areas.
  4. Turn the HVAC system OFF while mitigation work in the crawl space is being performed.
  5. Remove the sheet metal covers over return air ducts for the HVAC system.
  6. Treat and clean the joists and subfloor with Biocide.
    1. Microban or equal with the active ingredient Quaternary Ammonia is approved.
    3.  CONCROBIUM is not an approved product for this project.
      1. Fogging is NOT APPROVED.
  7. Apply Mold inhibiting coating to the joists, ban boards and subfloor (All exposed wood).
    1. Fosters 40-20 or IAQ 6000 are white approved mold inhibiting coatings
    2. Fosters 40-51 or IAQ 6100 are clear approved mold inhibiting coatings
  8. Install the sheet metal covers for the return air ducts.
  9. Have the HVAC system cleaned and sanitized per the NADCA ACR2006 standard.
  10. Pull Clearance Samples to confirm that the mold has been mitigated.
  11. Prepare a Clearance Certification to be held in the client’s real estate file.
  12. Install a permanent crawl space dehumidifier on a concrete base.
    1. Install a small recirculating fan operating 24-7 in the crawl space.
    2. OscarAir is recommended:
  13. Insulation between the joists could cause a future mold problem and will have little thermal benefit when a moisture barrier covers the earth; a dehumidifier and a recirculating fan are installed.
    1. If the floor of the crawl space is concreted (4” thick) fiberglass insulation is appropriate between the joists.