Moisture problems in the walls, crawlspace or attic can lead to other serious pest problems, such as wood-boring beetles and wood-decaying fungi in the floor joists. Mold/mildew growing on wood or insulation can also attract nuisance pests, such as plaster beetles, which can slowly build up in numbers and become a chronic problem. Keep a few important facts in mind:
  • Mold/ mildew on surfaces can pose some health issues and needs to be addressed as quickly as possible. For more information about mold indoors, visit the EPA website.
  • Mold/mildew growing on joists or beams does not mean that wood will decay.
  • Wood-decaying fungi do not grow below the fiber-saturation point (28-30% moisture) of the wood.
  • Problems with woodboring beetles are less likely to occur when the wood's moisture content is below 14%. This level may be difficult to reach immediately. Do not seal up walls until the wood moisture content is as least down to 19%.
  • You need a moisture meter to determine if you have excess moisture in your crawlspace, attic or framing wall.

At this point, the application of any pesticides to correct apparent wood decay is NOT the solution to the problem. Your priority should be to complete temporary or permanent repairs and to allow the wood to dry out as quickly as possible. It may take some time to get the wood moisture down in the crawlspace, but it is not impossible. Here are a few hints:

  • Make sure foundation vents open properly and they are clear of debris.
  • If possible, remove standing water from the crawlspace ASAP. Increase ventilation to the crawlspace. This can be a simple matter of opening the crawlspace door or using a fan to pull air OUT of the crawlspace, assuming that weather conditions (and availability of electricity) allow you to do so. You may have to use some large-mesh metal screening over the crawlspace door to keep out animals, such as raccoons, opposums and skunks.
  • Remove and replace place wet insulation in crawlspaces and walls.

mold on wood

wet subfloor and lower wall

wet insulation

Other References:

Preventive Home Maintenance Guide (NCCES-F&CS)
Moisture Control and Prevention Guide (NCCES-F&CS)

Safety tips for working around mold (OSHA)

For additional local advice on home repair and moisture control/reduction in storm-damaged areas, contact your county Cooperative Extension Service Center