Should I Leave My Crawl Space Door Open?

Should I Leave My Crawl Space Door Open?

Some people believe that opening their crawl space door helps control humidity levels. Unfortunately, this can do more harm than good. It can lead to several issues that worsen any problems you already have. 


Humidity is a problem in many parts of the United States, but there are other ways to manage it besides leaving your crawl space door open. If you constantly leave your door open, you may find yourself calling for frequent repairs.  


Why Leaving My Crawl Space Door Open Doesn’t Help Control Moisture 

If you live in an area known for high humidity levels, keeping the door to your crawl space open means letting in more damp air.  


You wouldn’t leave your front door open to help lower the humidity in your home, would you? Probably not. Wet air seeks dry air, so the air in your crawl space will try to balance itself when the door remains open. Damp air will rush in, increasing the humidity. 


Reasons to Leave Your Crawl Space Doors Closed 

An open crawl space door spells trouble for your home. It often leads to more extensive problems. 


The Stack Effect 

Air usually feels colder in your crawl space. When outside air gets into this area and mixes with the cooler air, it becomes more humid. Mixing these two kinds of air creates more moisture issues, which is troublesome for your crawl space. 


On top of that, warm air moves into your living spaces, bringing mold spores, dust mites, and more humidity. This process is known as the stack effect. It keeps causing more problems for you, your family, and your home.  


Mold Growth 

A warm, moist environment is the ideal place for mold. An open crawl space is the perfect place for it to thrive. When the door is left open, outdoor air enters and increases humidity inside the crawl space. 


High humidity is the primary factor in rapid mold growth. Not only does this create a structural concern, but it leads to health risks for your family. Mold triggers allergy symptoms, asthma attacks, and other respiratory problems. Keeping the crawl space door closed reduces moisture levels, limiting the growth of mold and protecting your home. 


Wood Rot  

When wood becomes exposed to excessive moisture for prolonged periods, it develops a fungal decay called wood rot. Open doors allow moist air to enter, which the wood absorbs. This creates the perfect environment for the fungus to grow, weakening your house and making it less safe. 


Wood rot can be challenging to detect early on, and by the time you notice it, it may be too late — your crawl space may have already suffered significant damage. Closing the door helps keep the wood in your crawl space dry and protects it from rotting. It extends the lifespan of your home’s foundation.  


Damp Insulation 

An insulated crawl space helps with energy efficiency. However, water gets in when the door remains open, dampening the insulation. It no longer works as well and doesn’t keep heat or cool air in as it should. As a result, your heater or AC system must work extra hard to maintain your comfort.  


Not only does damp insulation increase your energy bills, but the material also wears out faster when moist. Keeping your door closed stops water from getting in and helps your insulation do its job correctly. 


Energy Bills 

An open crawl space door provides easy access for outdoor air and related moisture to enter your home, which can directly impact your utility bills. Moisture causes the humidity levels to spike, making your HVAC system work harder to keep your home comfortable.  


Heating damp air is more challenging than heating dry air. It requires more energy, leading to higher utility costs. Closing your crawl space door will keep out excessively moist air and help limit the stress on your HVAC system.  


Poor Air Quality  

When your crawl space door is left open, moisture moves in. This increases humidity in your home, which can lead to mold growth and poor indoor air quality, making it difficult to breathe.  



Leaving your crawl space door open is like showing a welcome sign to rodents and insects. They see your crawl space as a haven away from the outdoor elements. Eventually, they may invade your house, leaving toxic droppings, eating your food, and destroying your property.  


Closing the door limits access to wildlife, making it more difficult for pests to enter your property. 



A crawl space is one method thieves might use to enter your home without being detected. If you use your crawl space for storage, leaving the door open makes it more vulnerable to burglary. Some homeowners even put an alarm system in their crawl space for added protection. 


Prepare Your Crawl Space With a High-Quality Door 

Investing in a quality crawl space door from a reputable company will help you minimize the problems related to having an open door. Cathmer Crawl Space Door offers many options for homeowners. Start shopping, and don’t hesitate to call us with any questions!  

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