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Why Your Crawl Space Smells (And How to Fix It)

How to Fix a Smelly Crawl Space

Your home is your shelter, your safe space, so if something is wrong or unusual, you want to get it fixed. If you’ve noticed a foul smell coming from your basement or crawl space area, there could be several reasons for it, some of which could be dangerous to your health. Don’t let it sit any longer, keep reading to find out what’s causing the smell and how to get rid of it.

Why does my crawl space smell? Crawl spaces and basements have long been hated and loved by homeowners. When they are safe and useful, they’re great aspects to have in your home, but when they weren’t build correctly or have suffered structural problems, they can be a nightmare to fix. Noticing that your crawl space is starting to smell could be because of the following reasons:

  • Moisture From Outside
  • Trash and Other Stored Items
  • Mold and Rot
  • Organic Matter
  • Leaks
  • Dead Animals and Their Waste


Unfortunately, none of these potential reasons are very appealing, hence the smell and some can take time and money to fix. Luckily, there are some solutions to your problem.

Moisture From Outside

Over the years, basements and crawl spaces have been known to have issues with water, most often coming from outside. Whether the area wasn’t sealed correctly when it was built, or the weather has disrupted the integrity of the foundation, crawl spaces often take the brunt of the problem.

Because of the nature of crawl spaces, they are often relatively cool compared to the outside temperature. When moisture and humidity from outside makes its way in and comes into contact with cool surfaces, condensation forms. This condensation can cause mold and rot – which is when you start to notice a musty smell.

The best way to prevent moisture from collecting inside your crawl space is to ensure it is sealed properly and that the walls and floors are covered in a vapor barrier. A vapor barrier will help protect against water from coming through the walls and up from the dirt or concrete floor.

vapor barrier for crawl space


Trash and Other Stored Items

Because you can’t see the crawl space, it can become a forgotten part of your house – until something goes wrong. Maybe you just moved into a new house, or you’ve lived there for years, either way, it’s a good idea to check for any junk or other stored items that have collected in your crawl space area over the years.

Hidden junk and trash can become great places for unwanted pests, animals, mold, and other nasty things to collect, causing an awful smell, and other potentially worse problems. If you don’t have any junk under your crawl space, this is a reminder to make sure you don’t start storing things there.

When you do go to remove any junk from your crawl space, it’s important to wear protective gear – gloves, eyewear, long sleeves, pants, and boots – you never know what could crawl out. And, if you’re worried about it, you can always call a professional or exterminator to come to take care of it for you.

How to Fix Smelly Crawl Space

Mold and Rot

Mold and rot are two words that no homeowner wants to hear. If what you’re smelling is musty, there’s a good chance that it is mold and that mold spores from your crawl space have made it into your home.

This can be alarming because it can be harmful to your health and costly to remove.

Many crawl spaces consist of wooden beams, which when consistently wet, will rot over time.

This rot can require a lot of work, time, and money to replace unsupportive beams, and then you’ll still need to fix the moisture issue.

Fixing this issue could encompass a lot more than just sealing off the area or removing junk, you may have to hire professionals to remove mold and replace beams. You won’t want to leave this problem for the next homeowner because inspections could mean the value of your home is less than what you hoped or expected.

If the problem is isolate in a small area you can utilize a mold remover to clean the area.

professional grade crawl space mold remover


Organic Matter

Most crawl spaces are just areas under the home that are relatively open to the elements and consist of a dirt floor. When this is the case, it can be very easy for organic materials like dead leaves, manure, decay, etc. to collect. When the crawl space is unsealed, the smell from the organic matter can easily make its way upstairs.

The best way to fix this issue is to, again, seal off the crawl space from the rest of the house, as well as to the outside elements. Another thing you can do to help is to pour concrete as flooring for the crawl space, eliminating the dirt floor and helping against any water problems.


Water Leaks

Speaking of water, leaks cause a lot of damage in crawl spaces. Whether it’s from groundwater or plumbing, leaks can cost you a fortune in repairs. Depending on where you live, this could be a more likely situation for you than in other places – due to freezing weather and consistently wet conditions.

The problem with leaks in the crawl space is that you likely won’t notice them until the damage has been done. Groundwater leaks will present themselves with puddles and pools of water on top of the exposed dirt or vapor barrier. You can fix this problem by installing a perimeter drainage channel and sump pump to help drain and expel excess water.

In the case of plumbing leaks, you will notice drips from inside the crawl space or standing water around tubs, showers, toilets, etc. The first thing you should do is call a plumber to fix any pipes that are leaking water into the crawl space. Once you add a vapor barrier to the area, a sump pump in this situation is also useful as it will expel any water that gets past the barrier.

crawl space wall leak

Dead Animals and Their Waste

If you’re like me, critters, snakes, spiders, and other creatures make you jittery and freak out a little. Unfortunately, crawl spaces are ideal homes for these kinds of animals – they’re dark and warm and give shelter from the elements. Sometimes, these animals will get stuck or die inside the crawl space, and soon you’ll be experiencing a strong decay smell.

At the same time, animal waste left behind can also enter the air vents of your home from the crawl space, causing a foul smell and other potential problems for you and your family. In these cases, the first step is to remove the animals and their waste.

Diseases and bacteria are unknown in these situations and so it is better and safer to hire a professional to take of this problem for you. Once the problem is removed, you should have an inspector come and advise you on how to proceed in protecting against such invasions in the future.

Related Questions:

How to Fix a Smelly Basement

Protect Your House and Your Family

Crawl spaces can unintentionally cause many different issues for homeowners. Instead of just reacting to problems that arise from your crawl space, there are some things you can do to prevent issues from getting out of hand.

  • Have a professional come out and inspect the area once a year. This will help make sure that if there’s anything that could become an issue in the future, it is caught in time – you will save lots of money and a huge headache.
  • Inspect the area yourself as the seasons change. It can be good to winterize the area and prepare for rain in the spring – it will also ensure that you’ll notice if anything is amiss.

Stop worrying about your crawl space – get it inspected and sealed, then go and enjoy your home with your family.

Written By

Hi there! My name is Matt and I write for Expert Home Report. I enjoy writing about everything related to home improvement, home tips and DIY. In my spare time, I'm either spending time with my family, doing a DIY project or learning a new skill.