Damp Crawlspaces: Problems & Solutions
In the pest control industry, we regularly enter crawlspaces for termite inspections and treatments, among other things. It’s interesting to see how many large, beautiful homes have perfectly manicured, pristine exteriors, but are a disaster area underneath. For many homeowners, the crawlspace is “out of sight, out of mind”–but this area is extremely important, as problems that go unnoticed can rapidly worsen and cause damage to the home. A primary area of concern–particularly during a humid Delmarva summer–is that of crawlspace moisture levels.
Homes in coastal areas are built with crawlspaces much more often than basements, due to high water tables, which can cause flooding. The problem is that coastal areas also have high humidity levels, often resulting in damp (or outright soaked) crawlspaces. This leads to mold, wood rot, and termite infestations, all of which destroy wood and may compromise the structural integrity of your home, resulting in costly repairs.
Condensation in this crawlspace has resulted in damp insulation and water dripping from pipes, forming puddles on the plastic sheeting below.
White mold is generally a surface mold, and does not significantly damage wood. Black or brown mold is a sign of rot, and requires immediate attention. Without getting too technical, let’s take a look at the numbers concerning wood rot:
3% wood moisture content = normal, with average temperatures and a relative humidity of 10%.
20% wood moisture content = level necessary for mold to occur.
23-26% wood moisture content = results from a relative humidity of 100%.
27-28% wood moisture content = level necessary for wood rot to occur.
As you can see, the difference between an extremely humid (but dry) crawlspace and a wet crawlspace is very small. Any extra water introduced into the equation will cause that difference. For example: how many homes have air ducts in the crawlspace? There’s a good chance that yours does, moreover, there’s also a good chance that the high temperatures and high humidity levels of August, coupled with the cool air flowing through the ducts, is resulting in condensation. This water might end up forming puddles throughout the crawlspace, or may soak insulation, or both.
Condensation on ducts; moisture levels also contribute to deteriorating insulation.
What can you do? It is commonly believed that ventilation is the answer to these problems. Many homes have solid crawl doors for the winter months, to keep heat in and cold out, and screened crawl doors for the warmer months. As well, foundation vents are usually closed in the winter, and opened in the summer, for the same reason. While this will go a long way in drying out a damp crawlspace, and preventing moisture from occurring, it might not be enough during the summer months. 
Even an exhaust fan might not be enough. Owners of crawlspaces that remain damp after ventilation should consider installing a dehumidifier, and possibly a sump pump to drain standing water. At Brasure’s, we recommend Santa Fe dehumidifiers, which are specifically designed for crawlspaces. These units run on less electricity than other brands, and are most effective at removing water from the crawlspace and lowering the relative humidity level. For pricing, call us at (302) 436-8140.
Additional tips for alleviating crawlspace moisture problems:
- Most crawlspaces built in recent years are covered in plastic, which acts as a vapor barrier. Determine which points of your crawlspace are the lowest, and poke small holes in the plastic there. If standing water occurs, this will assist with drainage, and will not compromise the plastic’s purpose as a vapor barrier/retarder.
- A sump pit can be constructed in the lowest point of the crawlspace, which is as simple as digging a hole and placing a perforated bucket in it, then surrounding it with small stones or gravel. A trench system and/or sump pump will help with drainage of flooded areas.
- Insulate ducts to reduce sweating, which contributes to condensation.
- There should be no openings between the living areas of the house and the crawlspace. Not only are these pest access points; they facilitate airflow between the two areas, which may adversely affect the quality of the air that you and your family breathes. Holes can be sealed invidually, or foam insulation can be applied throughout the entire crawlspace, which is doubly effective as it eliminates the problem of soaked fiberglass insulation, which shreds and falls down over time.
- The dryer vent should never lead to the crawlspace. This pipes in warm, moisture-laden air, and is also a potential fire hazard.
- Be sure that rain gutters do not drain directly against the foundation, which can lead to standing water in the crawlspace. Divert the water flow to as far away from the house as possible–three yards is usually a good distance.
- Ideally, the ground in the crawlspace should be highest at the center, and lowest along the foundation, so that water drains towards the edges.
Where applicable, follow these tips, and feel free to contact us for more information about damp crawlspaces, remedies, or Santa Fe dehumidifiers, which we now sell and install. Call Brasure’s at (302) 436-8140 or 1-800-908-1000. Visit our web site www.BrasuresPestControl.com for more details and information about damp crawlspaces and dehumidifiers.