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Do Crawl Space Vents Affect Your Home?

Venting the crawl space can elevate moisture levels and lead to problems in the crawl space.

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Crawl space ventilation appears to be a gray area for many homeowners. It’s because we’ve grown up with vents, so we assume they’re the best way of airing out your home. But are they? What effects do these fixtures have? Venting lets warm, moist air into your home, and this can result in: 

  • Extensive mold growth 
  • Pest infestation 
  • Damaged wooden supports and buckled floors 
  • High indoor humidity 
  • Condensation/water pools 

If you’re not sure whether to ventilate your crawl space or what steps to take to create a cool, dry, and comfortable interior, this article is for you. 

problems with crawl space vents

Should You Ventilate the Crawl Space? 

This question has been debated for decades in the U.S. and other countries. Studies show that venting in humid weather encourages outside air to get into the crawl space, and this increases the moisture levels

The reason is that warm outside air contains more vapor than internal air. When this air gets into your crawl space, it’s going to cause condensation and a myriad of problems. For this reason, building experts no longer advocate for simple passive venting or humidistat-controlled ones. 

Effective Crawl Space Moisture Solutions 

Negative pressures across the crawl space, insufficient return air paths, door closures, and lower AC settings can make the conditions down there unbearable. Things can get worse if you disconnect the return ducts or leave fans or fail to drain the condensate properly. Using an oversized AC unit won’t help matters either. And neither does a failing vapor barrier or poor site drainage. 

If you have persistent moisture problems, we recommend the following: 

  • Maintain the air conditioner thermostat just above the dew point (75°F) 
  • Eliminate long-standing negative pressures due to ventilation equipment 
  • Seal all existing ductwork tightly and create enough air pathways 
  • Increase moisture removal by installing a properly sized dehumidifier 
  • Remove all groundwater sources and apply appropriate moisture barriers 
  • Have durable vapor barriers properly installed 

Best Ways of Controlling Crawl Space Moisture 

Seal the crawl space from the moist outside air and close off the vents. Doing so converts the crawl space into a conditioned space. 

Install a 20-mil plastic vapor barrier over the floor and walls of your crawl space up to the grade level. This barrier will lock out moisture and make the environment less attractive to wood-damaging pests. Find out the sources of crawl space moisture and remove them. It could be the drainage spills around your home’s foundation, the rising dampness, or the in-slope grade.  

Seal air leaks around wiring, door frames, or pipes. This way, you’ll prevent unwanted air movement into the cooler and mostly dry crawl space area. 

Keep checking the crawl space interior for moisture. Do so at least once a year. Make sure the plastic vapor barrier is functional and intact. Check for outside water leaks, roof spillage, and leaky water pipes. All these can instigate moisture and crawl space mold

Benefits of Sealing the Crawl Space 

Closing vents and encapsulating the crawl space area has many advantages. It stops outside air from coming into the crawl space area. That means no moisture buildup that leads to condensation or mold growth. Your crawl space and your home will become much warmer, and the quality of the indoor air will greatly improve.  

You won’t have to deal with dust mites, pollen, dander, or mold spores that trigger respiratory problems. If heating costs were high, you’ll notice a drop in your monthly bills by up to 30%. You won’t have to rely on your HVAC to create the perfect indoor conditions as the temperatures and the air quality in your crawl space will match that of your home. Lastly, you will get a lot of clean, dry space that you can use for anything. Get in touch with the crawl space experts at Innovative Basement Authority for a free crawl space repair inspection and quote. We can help you seal and condition your crawl space so you can have warm, mold-free, and comfortable interiors.

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