Crawl Space Humidity: Preventing & Eliminating It

dry crawl space

Let’s get one thing straight: crawl spaces are not the greatest of mankind’s inventions; they shouldn’t exist anymore. The space is both uninviting and wet, and, can leave you with a ton of problems. Yet, they’re one of the most important spaces in your home. Neglecting your crawl space is sure to create issues. If you’ve been experiencing problems with humidity, rot, mold, or fungus, it’s time to kick it into high gear and get rid of the mess.

Why So Humid?

The humidity in your crawl space is caused when the ground’s soil (which naturally retains water) is exposed to open air. When the water evaporates from the ground, it makes its way into your crammed crawl space and creates a rather humid environment.

But, why do crawl spaces even exist? The reason houses or buildings have crawl spaces is to create a space between the ground and the building. However, some crawl spaces (or basements) are finished with poured concrete, making them less likely to be humid; whereas others seem “unfinished” and simply have earth below the building’s structure. Seemingly unfinished crawlspaces are those most prone to humidity because of the ground’s exposure to open air.

Though, water can still infiltrate through other openings such as under your home’s footing, between the footing and your home’s walls, through small cracks, or any other space that isn’t watertight, thus creating a humid environment. A highly humid crawl space can negatively impact your home or building’s structural integrity.

Signs of Humidity

Here are signs that may indicate high humidity levels in your crawl space:

  1. The air in your home is rather humid
  2. Mold begins to appear on the walls near your floor
  3. The cost of heating and cooling your home keeps going up
  4. There are more insects in the building than usual


Crawl Space Encapsulation | Getting Rid of Mold & Humidity

In this case, the condominium’s crawl space was highly humid and needed to be taken care of before the new owner took official ownership. Proper decontamination and encapsulation processes were followed by our Verified Contractors to remedy the situation!

Why Getting Rid of Crawlspace Humidity is So Important

Getting rid of humidity in your crawl space is crucial. However, low levels of humidity are normal, and you shouldn’t be alarmed. You should act only when humidity levels are high. Why? Because it can not only be detrimental to your health and well-being, but also to your building’s structural integrity.

Here are the top 4 reasons you should protect your home from crawl space humidity:

1) To prevent mold and contaminants from forming, and to protect your heath & well-being

The last thing you want for your home and your family is for harmful contaminants to form under your home. To prevent their development and growth, it’s important to cut all sources of humidity to your crawl space.

The ground’s soil is naturally moist. However, when the earth in the ground dries, the water vapour moves upwards and slowly makes its way into your home. Any air found in your crawl space makes its way to upper floors, thus resulting in any potential contaminant formations. If the air is contaminated with mites and mold, it can severely affect your your health – especially for those with asthma and allergies.

Also, if you use your crawl space to store old paint containers and solvents you’re likely to breathe in fumes from these toxic products. Floors are never airtight. So much so that almost a third of the air you breathe in your home comes from the crawl space. The same goes for natural gases that are potentially toxic. If radon, for instance, is released from the ground, it undoubtedly makes its way into your home too. To prevent the spread of mold and fungus and other contaminants, you must eliminate all sources of humidity from your crawl space and not store any toxic materials in there either.

It’s impossible to permanently dry out your land. Though, it is possible to control the humidity levels your home is exposed to. Cement block walls are quite common for homes with a crawl space. Though, they remain vulnerable to moisture and water vapour. Other materials should be favoured for your crawl space walls, such as poured concrete.

Mold also craves inactive, humid organic matter. So, if your insulation or wood structure is very humid, it won’t take long before mold and other fungi take over. Yet another reason why it’s important to keep as few items as possible in the crawl space.

2) To save on energy costs

A typical crawl space usually causes higher energy costs than a finished basement. Even if its walls block the air from flowing in (hot or cold), the humidity level in that air will be higher as it comes into contact with the ground’s soil. In addition, damp air is harder to heat or cool than dry air. You’re likely to pay, on average, between 15% and 25% more annually to heat or cool your home if it rests on a crawl space that is directly exposed to the ground.

3) To ensure structural integrity

Prolonged exposure to moisture and various sources of contaminants can affect the condition of your beams, joists, and sub-floor. In the long run, the risks associated with weakening your structure can not only affect your physical safety, but even affect the resale of your property. Not to mention the premature curling of wood floors, fogging windows, and so on.

4) To keep away insects

Insects love humid crawl spaces. Once they build their home there, they’re likely to make their way into your home as well. If you store non-chemical products in your crawl space, you’re sure to find a colony of insects living in your “dedicated” storage space. Installing thermal insulation is a great solution to keeping them away.

humid crawl space

Is Ventilation an Adequate Solution to Preventing Humidity?

When facing crawl space humidity problems, many homeowners’ natural reflex is to install ventilation. However, this can have a compound effect on the issue at hand. The ventilation system will actually draw waterlogged air to the crawl space on rainy days, worsening the situation.

During summertime, the relative humidity phenomenon comes into play as hot air amplifies the situation. Essentially, in summer, the cooled air inside your home will be even more humid than the one outside. And, in the winter, the ventilation system will continuously draw in dry, but cold air into your crawl space. This means that your floors will be much colder, and you’ll need to improve the occupants’ comfort by heating more than usual. In both cases, depending on the weather, ventilation sometimes leads to more condensation and encourages the spread of mold while contributing to wood rot – which is besides having to pay higher energy bills!

The vents in the walls are also new openings through which additional water can enter. Your crawl space should be considered as a habitable basement (i.e. a space you would be “comfortable” living in) and maintain a temperature and humidity level that will avoid structural and health problems.

humidity in crawl space

What to Do with Crawl Space Contaminants

Once you notice crawl space contaminants or mold, it’s crucial you act quickly. This will avoid them from spreading. Here are 4 steps on how to remove contaminants from a crawl space and make sure they don’t come back:

1) Decontaminate your crawl space as quickly as possible

If you have mold or other types of contaminants, such as fungus, it’s important to get rid of them quickly as they could affect your  – as well as your building’s – health & well-being. Getting in touch with decontamination professionals is surely the way to go.

2) Repair, patch, and block sources of crawl space infiltration

Any gaps where water and/or can air make their way into the house play a role in how well you can control the humidity levels in your home. Watch out for concrete block walls or stone rubble walls that are porous. They can have many mortar joints that have deteriorated over the years. If that’s the case, you can get your joints repointed by a masonry contractor.

Another reason why water might be making its way in is because of French drain issues. You might need to replace your home’s French drain and get a new waterproofing membrane installed around the crawlspace walls.

Keep in mind that properly insulating vents will also help (and save on energy bills)!

3) Isolate your crawl space from the ground and from your home

Installing a polyethylene membrane on all surfaces of your crawlspace will prevent contaminants from making their way into the space. However, be sure to get an underlay installed with a water recovery system so that water doesn’t accumulate within the newly insulated space. Not only will it help getting rid of contaminants, but the area will now be clean and pristine.

4) Ensure adequate air circulation and dehumidify your crawl space

Installing a powerful dehumidifier in your crawl space will allow you to control the humidity levels and mold. Humidity levels will be so low that you’ll prevent mold or other contaminants from spreading.

Finding the Right Contractor to Help You Out

There are many solutions to removing humidity in your crawl space. If you’d like to change your current crawlspace to a poured concrete one, you’re likely to need a foundation expert; if you need to fix some concrete block joints, you’ll need a mason; and if you need to replace your French drain, you’ll need a French drain contractor.

Our Renovation Advisors are here to help you find the right professional to help with your crawl space issues. They’ll gather up to three Verified Contractors to quote on your project. Each one will compete against the others to win you over. Knowing they’re competing against others ensures that you get a fair price! Plus, our advisors will be there to help you compare and understand each quote you receive. Our service is at no cost, no obligation to you. Call us or fill out our form today!

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