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How to Handle Humidity Under Your Home


A moisture problem underneath your home is a cause for concern. The related humidity effects can be serious and can include unpleasant indoor odors, unhealthy mold growth, pest damage, structural decay, foundation movement and HVAC system deterioration. Here's a helpful primer on the possible causes and what can be done to solve the problem:


Before you can take steps to solve a moisture issue underneath your home, you need to identify the cause, which might be:

  • Plumbing system leaks: You may have leaks around bathroom, laundry room and kitchen plumbing fixtures or appliances or deterioration of the home's water pipes or sewer lines.
  • Sprinkler system issues. There may be flaws in the sprinkler system fittings and lines, or you may be watering plantings around the house's perimeter excessively or too frequently.
  • Drainage problems. Inadequate slope around the foundation or poorly-functioning gutters can result in ineffective drainage and water seepage under the home.


Depending on the cause and the extent of the humidity problem under your home, you may need to:

  • Fix plumbing leaks. Have a licensed professional find and fix any leaks that are allowing water to escape the plumbing or sprinkler systems and seep down to the foundation level.
  • Repair the gutter system. Make sure your gutters can handle the volume of runoff from your roof, that the downspouts are expelling water an adequate distance away and that all the system components are in good repair.
  • Correct drainage issues. You may have to increase the ground slope, or install a french drain so water runs off instead of pooling along the foundation.
  • Boost ventilation. Have foundation vents installed and add mechanical ventilation if necessary to help clear out moisture and humidity from under the house.
  • Add a vapor barrier. A properly-installed and sealed plastic vapor barrier may be needed to keep moisture from entering your home's crawlspace or basement.

If you're looking for ways to minimize humidity effects under your home, visit our Valley Heating, Cooling, Electrical and Solar website or give us a call at (408) 868-5500.

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