The condition of crawl space can have an impact on the air inside your home. A field study of homes in the Pacific Northwest found that around 40% of the air in homes came through the vented crawl space.
This means you can sometimes notice signs of a crawl space problem inside the house. The signs can be different depending on what is happening under the house. Here are some things you can look for inside your home and then check in the crawl space.
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A Musty Smell That Gets Worse in Summer
If you notice a musty smell, then this is your first sign of problems in the crawl space. This smell is somewhat damp or stale and usually found in places with poor ventilation and excess moisture. Humid conditions make damp wood, soil, insulation, and mold contribute to a stronger odor. The smell is particularly strong when the AC is running, as it allows air to move into living areas from the crawl space.
Sticking Doors and Diagonal Drywall Cracks
Doors that suddenly start sticking can be a sign that something is shifting around your home. You may notice that a door that opened normally before now rubs against the frame or becomes difficult to close. Also, if there is a movement in the structure, then you can possibly see diagonal cracks in drywall. They are particularly visible around doors and windows.
Two causes are common:
- Piers spaced too far apart: The girder sags between supports, and the floor sags with it.
- Settling piers: Weak soil lets a pier sink, leaving a gap between its top and the girder.
Look for that gap, or for stacks of wood shims on top of the piers. Both mean the floor has been moving.
Ductwork That Sweats or Drips
Ductwork that feels wet or has water dripping from it is another sign of excess moisture in the crawl space. This usually happens when warm air comes into contact with cold AC ducts which causes condensation to form on the outside.
Check the area around the ducts for wet insulation, water stains, or mold. You should also look for other sources of moisture in the crawl space, such as standing water or poor ventilation.
Insulation Hanging or Falling From the Joists
Insulation that is hanging down or falling from the floor joists can be another sign of a crawl space problem. Moisture makes insulation heavy and causes it to lose its position over time. You may also find damaged or missing insulation when checking underneath your home. This can affect the temperature inside your house and make your heating or cooling system work harder.
Joist Moisture Readings Above 19%
An inexpensive wood moisture meter replaces guessing with a number. Take readings on several joists, especially near outer walls and under bathrooms. Then compare them with these building science benchmarks:
- Below 16%: Too dry for mold to grow
- 16% to 19%: Mold becomes possible
- Above 19%: Wood rot becomes a real risk
Readings can be high on certain days when there is a rainfall or storm. If you notice high readings even after a week then this is a strong sign of moisture presence otherwise.
Brown or Black Growth on the Wood
Brown or black growth on the wood can be a sign of excess moisture in your crawl space. You may notice these spots on floor joists, support beams, or other wooden parts underneath your home. The growth can appear as small patches at first but may spread if the moisture problem continues.
Check the surrounding area for damp wood, water stains, or poor airflow. Brown or black growth is often rot fungus breaking down the wood. Press the spot with a screwdriver. If the tip sinks in, that joist may need repair or replacement.
Your DIY Fixes Keep Failing
Many homeowners try to dry things out with vent fans or by leaving vents open longer. Both solutions are not recommended in humid climates. Pulling more outside air through the space can bring in more moisture than it removes.
If the smell, dampness, or mold keeps coming back, the cause is usually drainage, grading, or an open foundation design. That’s the point where professional crawl space repair services can trace the source and fix it with vapor barriers, encapsulation, drainage, or structural support.
Endnote
Crawl space problems can show up in different parts of your home. A musty smell, sticking doors, wet ductwork, damaged insulation, or growth on the wood all point to an issue underneath the house.
Check the crawl space if you notice any of these signs and look for moisture, leaks, mold, or damaged materials. Have a professional inspect the area if you find a problem that you cannot identify or fix yourself.
