Resource Article

Crawl Space Smells and Moisture: How to Remedy the Problem

Blake Heron

Catch a waft of something musty when trying to access your crawl space? If this is your current home issue, you’re not alone. Countless homeowners deal with crawl space smells daily; sometimes, these smells even come back after being eliminated the first time.

Just remember, this musty smell doesn’t have to be your reality forever. You just need to get to the root of your problem and take proper action.

If you don’t know the right method of eliminating your smelly situation, or you need a new one, you’ve come to the right place. All you need to do is get comfortable and keep reading.

What’s Causing Your Crawl Space Smells

The first thing you need to do when trying to fix your crawl space smell is learning what the cause is. There are dozens of different factors that could cause this problem and dozens of different remedies. The key is figuring out which factor to fix and what to fix it with.

You could try spraying some air freshener in the space, but the smell won’t go away if it’s caused by something below the foundation.


One of the biggest causes of crawl space smells is moisture. There are multiple sources of moisture in crawl spaces including: exposed damp soils, ground water flooding, humid outside air, plumbing leaks, etc.

If this is the case, the first thing you need to do is address each source of moisture strategically.

For damp soils, we recommend a professional moisture barrier.

For ground water and flooding, we recommend french drains and sump pumps unless the area of flooding is very small, in which case sand could be appropriate.

For humid outside air, we recommend sealing the crawl space with an encapsulation and installing a dehumidifier.

Mold & Mildew

One of the most notable causes of musty smells is mold. If your crawlspace smells strongly of must, this might be your problem. You need to note that mold grows quicker in damp environments.

If you have/had a moisture problem in your crawlspace, check for mold as soon as possible. Some types of mold can get very dangerous when ignored and need to get cleaned up quickly. You can do this by yourself or professionally if you do not know how to do it alone.

If the mold comes back after you’ve cleaned, you need to fix the moisture levels in your crawlspace.

Dead Animals

As awful as it might be, the cause of that rotting smell in your crawlspace could very well be a dead animal. It is not uncommon for rodents and other wildlife to seek refuge in your uninhabited spaces. When they do this, injured or sick animals tend to die and decay where they hid.

The only way to know for certain if this is the root of your problem is by going down there and checking it out. If you see a dead animal, please take the proper precautions and dispose of them safely. They may have contracted a disease you don’t want to get.


Your crawl space is likely the home to most of your plumbing. If a drain pipe is broken or rusted badly, the result could be sewage leaking into the crawl space.

This smell can be particularly bad. To remedy the situation, the sewage must be removed, the affected area must be disinfected, and the plumbing leak fixed.

Why Fix Crawl Space Smells

Once you figure out the cause of your crawlspace smell, you may get a little hesitant to fix it. Some home repairs can be pricey, making it easy to push them to the back burner. But ignoring something as strong as a crawl space smell will only make the problem worse.

It will soon start to leak into your home. Once this happens, the structural issue or mold causing this smell has progressed, making it all a bigger and more expensive thing to fix. In this case, proactiveness will save you a lot of time, effort, and money in the future.

Along with this, mold can become dangerous when allowed to progress. It can cause breathing issues such as Pneumonia or Bronchitis. Mold will also start to decay whatever it is growing on, even that dress you wore to your high school prom.

How to Eliminate Crawl Space Smells

After finding and fixing the root of the smell, your crawlspace may still reek of must. This is fairly normal, especially if the smell was strong. Chances are the smell will go away with time after the source of the musty smell is removed.

Pump Standing Water

If your house crawlspace smell was caused by a leak, water may linger after you patch the hole. When this happens, your next step should be figuring out how to remove it. One of the easiest ways to do this is by pumping the water.

You can do this by contacting a crawlspace company and getting one installed professionally. The best thing about this method is the pump will stay and prevent any more future water buildup.

Install Flood Prevention

If your crawlspace is known to acquire standing water during storms, the only way to keep your space dry and mold/must-free is by professionally installing flood prevention. This can come in the form of french drains, sump pumps, gutters, drains, or downspout extensions.

You should call a professional for help but some fixes can be DIY. However you do it, just make sure it is done right. Your nose will thank you later.

Clean, Clean, Clean

When it comes to removing musty crawlspace smells, cleaning is your best friend. If mold wasn’t the culprit of your musty smell, a good clean would still do you well. This is how you can remove any damp materials or locate any potential smell collectors.

Your crawl space would likely benefit by removing all the dirty, dusty, stinky items and installing a new clean moisture barrier.

Open the Door

Leaving the door to your crawlspace open is one of the easiest ways to decrease the intensity of the musty smell. Many times, smells will not vanish when trapped. This is simply because they have nowhere to go.

If your crawlspace opens to the outside, find a sunny day to leave the door open. Just remember to shut it before any animals decide to spend the night in there. If your crawlspace opens inside your home, just open the door for as long as you can and allow fresh air to enter the room.

Turn On a Fan

When musty smells begin to accumulate in a room, the stillness of the air helps it persist, making it stronger. Turning on a box fan or finding another way to circulate the air will stir it up and push it elsewhere. This will also allow fresh air to enter the space quicker.

If your crawlspace opens to the outside, you may not be able to use this method, but you can leave the door open on a windy day. This should have a similar effect and help with the smell as well.

Call a Professional

If the smell in your crawl space is persistent regardless of what you do, call a professional. Chances are you haven’t properly taken care of the issue or found the root of your problem. A professional will have the proper equipment and knows exactly what to do to eliminate the smell.

All you need to do is give a reliable company a call for an assessment and quote. After this, you can schedule an appointment and finally get to the real root of your problem.

Fix Your Crawl Space

If the solution to your crawl space smell requires professional help or you want a second opinion, check out our services at BAY Crawl Space & Foundation Repair.

Our team of experts knows exactly how to correct the most common crawl space issues and are more than willing to help you out. We promise to have you smelling fresh air in no time.

When you are ready to get to the bottom of your crawl space smells, explore our website and fill out our contact form. After this, just wait; we will contact you soon.

Written By Blake Heron

Blake has specialized in crawl space & foundation repairs for over 10 years (since 2012). His prior engineering and business degrees from James Madison University in VA prepared him for a mastery of problem solving with crawl space & foundation repair issues. He is one of America’s top experts on crawl space encapsulation. As Founder of both ‘BAY Crawl Space & Foundation Repair’ as well as ‘GridLock Foundations’ he is a leading industry expert on crawl space foundation repairs.

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