If you think about all the ways you can get sick, your list probably starts with external sources. Getting sneezed on or coughed on are generally pretty high on that list.

But there are parts of your home that can also compromise your immune system, release pathogens into the air, and make you sick in a variety of ways.  And one of the worst among them is your home’s crawl spaces.

First we’re going to look at the ways that your crawlspace might be making you sick, and then we’ll look at some signs that will help you diagnose the source. By the end of this guide, we hope that you’ll better understand how your crawlspace can impact your health and your options for remedying it.

Mold and Mildew

Whether it’s due to some standing water following a rainstorm or simply your dirt floor, water evaporating can damage your insulation and wood, and it can eventually come into the house. Below are some of the things that mold and mildew exposure can do to you.

  • Chest tightness
  • Cough & postnasal drip
  • Having trouble breathing
  • Itchy nose, throat and eyes
  • Scaly, dry skin
  • Sneezing
  • Stuffy or runny nose
  • Watery eyes
  • Wheezing

These are just some of the symptoms that you may have if you have mold and mildew in your home.

Pests & Their Droppings

When your crawl space has moisture, it is very is very attractive to things like mice, rats, snakes, spiders, termites and other things.  Although these are more annoying than anything, there are some venomous species that can cause very painful bites.

Venomous Spiders

  • Black widow
  • Brown widow
  • Chilean recluse
  • Desert recluse
  • Yellow sac

Mouse Droppings Dangers

  • Hantavirus – This causes chills and fever and is due to the feces and urine of deer mice.
  • Salmonella – Mice run over cabinets, counters, and pantries while carrying bacteria and dirt. When you leave food out or in cabinets can spread salmonella which can lead to food poisoning.
  • Lymphocytic Choriomeningitis – This can cause neurological issues such as meningitis and is due to fresh droppings, saliva and urine exposure from mice.


Radon can’t be smelled or seen, but it can be found in almost all types of soils. It comes from naturally decaying uranium. It moves through your ground and then into the air. Eventually it gets into your house. Lung cancer has been linked to exposure to radon, and it’s the top reason that people who don’t smoke get lung cancer.

You may start out with having trouble breathing, wheezing that persists or a cough that hangs around. Other types of symptoms that you might have are having blood when you cough, experiencing chest pain, and losing weigh when you’re not trying to.

While Radon is generally a bigger issue in other states, there are some parts of California that have higher radon concentrations as well. For example, Belmont, Menlo Park, and Atherton all have much higher than average radon potential, so it’s important to test your home at least once every few years.

Exposure to Outdoor Contaminants

If you live in an area of California where there is a lot of pollution, the vents that your crawlspace has are going to let the pollution into the crawl space. This is eventually going to get into your house. This bad air quality often will cause respiratory issues, asthma and allergies worse.

But why does this happen? We have to start at your crawl space. If your crawl space has a dirt floor and is vented, it’s not a good idea. It has a flawed design, which reduces air quality for your home. Your home over your crawl space is similar to a huge wick, drawing the moisture in from the ground.

In general, the crawl space’s dirt is much drier than that dirt surrounding your foundation. This means that moisture is wicked into your crawl space from external dirt. After it’s in your crawl space, that moisture goes into the air. This water vapor goes up and then settles on your subfloor, floor insulation and ductwork.

When it’s warm, the surfaces and air in crawl spaces are usually cooler than the air outside. As humid, warm air goes into crawl spaces through vents, it starts cooling. This results in increasing relative humidity. This is because warm air is able to hold much more vapor when compared with cool air. The condensation will gather on floor joists, subfloor, and ductwork, and this can result in the growth of mold.

Does Your Crawl Space Have a Problem?

Now that you know of the health problems that your crawl space can create, how do you know what to look for? Below are some of the things that you want to look for.

Some of the most common signs that you have moisture in your crawl space are:

  • Moisture or mold damage in your living area or crawl space
  • Smelling something musty in your living area
  • Sweating on your AC ductwork or your equipment
  • Sweating on your water pipes, truss plates or insulation in your crawl space
  • Hardwood floors buckling
  • High humidity levels in your home
  • Infestations of insects
  • Wooden frames rotting

Now that you know the ways that your crawl space can make you sick, it’s a good idea to have someone come and take a look at it to see what can be done. The sooner you have the crawl space inspected, the quicker you can help your house and your family be a lot healthier than it is right now.

You can also purchase Radon testing kits online or in stores so that you can check and see if you have a problem with Radon. The affects won’t be felt immediately, but years down the road it can cause serious health issues like lung cancer.

Furthermore, there are other things you can do around the house to improve your indoor air quality. If you have central air, cleaning your vents and replacing your filter can have a bigger impact than you would expect. Adding a dehumidifier to parts of your home that retain moisture can also be helpful, especially if mold is an ongoing problem for you. Even getting a new house plant can help.

But if you haven’t had your crawl space inspected or cleaned in the last few years, fixing that will have the biggest impact on your indoor air quality. Have your crawl space inspected today and enjoy more breathable air and a higher quality of life tomorrow.