Preventing Mold in Your Crawl Space

Spend a lot of time in your crawl space? No, we didn’t think so. That hollow, dark space beneath your home probably doesn’t feel like the go-to spot for hanging out or entertaining. Dark, small, and filled with obtrusive wires, pipes, and ductwork, your crawl space isn’t exactly the most hospitable place for people. But to mold? Crawl spaces the fungus equivalent to an all-expenses-paid trip to the Bahamas.  

Not only does mold thrive on the moisture which tends to accumulate in tight, dark enclaves like attics and crawl spaces, it also loves to feed on the organic materials that abound. 

Although most crawl spaces may have ideal conditions for mold, there are steps you can take to prevent infestations from taking hold. Read on for our guide on how to prevent mold in crawl spaces.

How to Prevent Mold in Your Crawl Space

When it comes to preventing mold, knowledge is power. Let’s take a look at the measures you can put in place to prevent mold:

Step 1: Find Your Crawl Spaces

Whether you’ve lived in your home for decades or have just bought a brand new welcome mat, it’s important to assess what a crawl space is and where they are in your home before we get to the how of mold prevention.

Crawl spaces are tight, hollow areas beneath your home that function as the operational core of your home, housing critical equipment like:

  • Air conditioners
  • Heaters
  • Plumbing pipes
  • Electrical wires
  • Ductwork

Keep in mind, not all homes have crawl spaces—54% of homes are built right on top of concrete slabs, and 30% of homes have basements. 

Why Do We Have Crawl Spaces Anyway?

If crawl spaces roll out the red carpet for mold, why are they so integral to our homes? These small enclaves we know as crawl spaces serve a functional purpose, acting as the barrier between the ground and your floor. 

A barrier can be particularly useful in flood zones and coastal areas, where rising water levels might push against concrete slabs, creating cracks, or make unfortunate inroads into a basement.

They also offer important benefits for our home’s health, including:1

  • Access – Crawl spaces may be tight, but they provide easy access to a home’s plumbing, electrical, and HVAC systems. If you need repairs, crawl spaces can serve as a centralized hub. Unlike with a finished basement or concrete slab, you won’t need to rip up any floors or break into the drywall for access. 
  • Safety – As crawl spaces store your plumbing and water pipes, they serve as a crucial buffer in the event of leaks, keeping the rest of your home dry and free from damage.
  • Flexibility – Crawl spaces provide a storage and safety solution for homes that are built on lots that can’t accommodate traditional basements, due to soil type or sloping.

But as useful as crawl spaces are, they can also provide the perfect environment for unwelcome guests—mold.

Step 2: Understand Why Mold Loves Crawl Spaces

It turns out that understanding what makes crawl spaces so appealing for mold is essential to preventing its takeover.

So why does mold feel so at home in your house’s most inhospitable space? 

Mold spores are discerning travelers. They go everywhere, but they don’t stay just anywhere. They float through the air, searching for the perfect wet spots where they can put down roots and prosper.2

To mold, a crawl space feels like a beachside resort. The conditions? Perfectfor unwinding—as dark and damp as could be. Then, there’s the buffet. It’s bottomless, filled with tasty filled with the kind of organic food that mold loves to eat, including:

  • Wood
  • Insulation
  • Rotting Leaves
  • Dirt
  • Insect droppings

Mold, likely, adores the accommodations that come with crawl spaces. Moisture is almost guaranteed to be a constant, thanks to:

  • Condensation – Some crawl spaces are ventilated, which can bring warmer air into the cooler space and result in droplets of condensation on the cooling vents. Those wet droplets can accumulate over time and contribute to a moist environment that attracts mold spores.
  • Leaks – Crawl spaces can be useful for containing leaks and the fallout from burst pipes. But if water damage or plumbing failures occur within their bounds, they can become fertile ground for mold infestation.
  • Dampness from the ground – The moisture from the earth can rise into your crawl space, introducing a constant level of dampness that breeds mold. 

Step 3: Make a Prevention Plan

We know why mold flourishes in crawl spaces. They’re dark, wet, and fully stocked with food. But how can we prevent these stubborn spores from taking hold?

By addressing the environmental conditions that support its growth, you can put in place prophylactic measures to deter infestations and maintain the safety and integrity of your home. 

  • Insulate the space – To address moisture that rises from the ground, insulation installation may just do the trick. Try insulating the floor of your crawl space with plastic sheeting. Contractors can also lay down a vapor barrier, which may resemble a thick rubber, to prevent excess moisture.1
  • Check your ducts and pipes– Make checking your vents and pipes for leaks a regular habit. Doing so can put your mind at ease and help you remedy any standing water before mold can move on in.

Be sure to confirm that your dryer vents release moist air and condensation outside, rather than within your crawl space. Furthermore, if you live in a cooler climate, be sure to check that your pipes are insulated so that they don’t freeze and burst during the winter months.

  • Use a dehumidifier – Dehumidifiers work by drawing in warm air, collecting its condensation into a storage tank, and recycling it into the space as cooler, drier air.4 These machines can bring down the humidity of a room by 30 to 50 percent 6and can be particularly useful as a moisture-mitigation device in crawl spaces.
  • Try a sump pump – If your house is built on a slope that makes crawl space water accumulation nearly unavoidable, avail yourself of a sump pump—a tool that pumps out water and sends it down storm drains or wells.5  If you already have a sump pump, check to make sure that it’s still viable. These tools have a relatively short lifespan, lasting around 10 years (but sometimes less with frequent use).5 
  • Space out your gutters – Do your gutters flow far enough away from the entrance of your crawl space? Or do they release water and rotting leaves (mold’s favorite combo meal) nearby enough that they’ll trickle down below and encourage crawl space mold growth?
  • Keep it tidy – Yes,
  • your crawl space might seem like the perfect place to store those boxes that you can’t throw away, but can’t bear to look at any longer. As convenient as it may appear as a long-term storage solution, your crawl space is not the answer for those baseball cards from 1987 or the ski pants that never saw the bunny trail. 

The more clutter that lives in your crawl space, the more food that mold has to feed on. Plus, items you store can get in the way of the airflow that can prevent moisture build-up.   

These steps can be implemented one by one (in no particular order) or all at once to ensure your home stays mold free.

Bonus Step: Do You Already Have Mold? What to Look—and Smell—For

As delightful as crawl spaces may be for mold, they can be dangerous for humans—fostering the spores and splotches that can provoke allergic reactions, degrade the structural integrity of their homes, and cause unseemly stains and smells. 

Worried that you might have mold in your crawl space? Here are some common signs that may indicate that you’re dealing with a mold infestation:3

  • Warped or stained baseboards
  • An earthy, musty scent that’s coming up from below
  • You or your family members experience cold-like symptoms unrelated to a virus, including runny noses, irritated throats, or headaches

Mold Issues? Give Attic Construction a Call 

Mold can be pretty sneaky, hiding out in those crevices and corners that you never think to check, vibing off of those very areas that you actively avoid. 

That spooky bathroom in your basement? The attic where you swear you heard a bat? The crawl space—that dingy, gloomy cellar that you suspect is important but can’t quite figure out?

These spaces are havens for mold, especially vulnerable to infestation thanks to their delectably dark and damp environs. They’re also risky zones for humans, who can get sick from the allergens and pathogens that can be released by mold spores.2

If you suspect that one, or various types of mold are lurking in your home’s hidden spaces, run—don’t crawl—to Attic Construction. Our team of experienced technicians will address any conditions that might contribute to mold growth and infestations of all kinds—whether from mold, rodents, or bacteria—through services that include:

We know that it can be daunting to explore what’s going on in your crawl space and attic, so leave it to us. We’ll begin with a thorough inspection of your crawl space and attic, check for vulnerable entry points and contaminations, and come up with a comprehensive action plan to treat—and prevent—dangerous damage.

Plus, we’ll handle all the nasty bits—cleaning up any animal droppings, bugs, or mold stains in your space, so that your home feels, and smells, as safe and healthy as possible.  

Ready to rid your crawl space of those sporous explorers? Call us today and we’ll get to the bottom of it.


  1. Homelight. Help, I need to know ‘What is a crawl space’ before buying a house.
  2. EPA. A Brief Guide to Mold, Moisture and Your Home.
  3. Healthline. Mold: Symptoms of Exposure, Risks, and More.
  4. Healthline. What Does a Dehumidifier Do?
  5. Country Living. What’s a Sump Pump, and How Does It Work?

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