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Clean Crawl Space

Crawl Space Waterproofing

Most homeowners don’t give much thought to their crawl space, but it contributes to your living conditions a lot more than you think.

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Because of the way crawl spaces are structured, they often get flooded with water or too much moisture can accumulate in the small, enclosed area. This is where the problem lies with crawl spaces. The water needs to be kept out or multiple problems can arise. An inadequately kept crawl space can bring mold, pests, high levels of humidity, rot, and structural deformities to the actual house itself. 

Luckily, there are a few solutions to this problem. Here’s everything you need to know about waterproofing your crawl space. 

Clean Crawl Space

The Most Effective Crawl Space Waterproofing Methods 

When a crawl space is flooded or has high levels of humidity, multiple problems can arise. When unencapsulated, crawl spaces attract pests such as rats, cockroaches, and termites. The humidity in the crawl space can also make it harder for your AC to cool or heater to warm your home, thus raising your electricity bill. 

Humid crawl spaces are also a health risk. Due to the stack effect, which is how air moves through your home, the dust, mold, and whatever else is in your crawl space gets brought up and pollutes the air in your home. This can lead to some serious allergies. Long-term exposure to contaminated air can cause irreparable damage to your lungs, throat, and sinuses. 

There are multiple things a homeowner can do to not only waterproof a crawl space, but also maintain more appropriate humidity levels. When looking to waterproof a crawl space, many homeowners see the different tools and methods used by contractors and decide they only need to choose one. However, the best thing you can do for your crawl space is fully waterproof it. After all, the conditions of your crawl space impact the way you go about your everyday life.  

  • Interior Drainage and a Sump Pump 

Crawl spaces are usually between two to five feet high. A vast majority of North Carolina’s water table can be found five to 10 feet below ground. Because of their proximity to the water table, many crawl spaces in North Carolina are prone to flooding, especially during the months with the most precipitation, which is during the summer.  

If water is getting into or flooding your crawl space, you must find a way to get it out and keep it out. A properly functioning waterproofing system including interior drainage and a sump pump will help you do just that. 

A specially designed interior drainage system is placed in the crawl space floor to collect seeping water. Typical crawl space floors are dirt, but don’t worry about this system clogging. It is surrounded by a filter fabric that prevents dirt, mud, sediment, and other debris from collecting in the drains. Any water collected by the interior drainage system is then directed to drain into a sump pump system. The sump pump then pumps this water out of the crawl space and away from the home. 

Having a sump pump is one of the best ways to keep water out of the crawl space, not to mention one of the most convenient. Homeowners who don’t have a sump pump but are always on top of flooding problems in their crawl spaces have to go through the trouble of manually getting rid of the water. This is extremely time-consuming and tiring. Not to mention, it puts the homeowner at risk because they come in contact with pest droppings, fungi, and other bacteria present in the crawl space. A sump pump eliminates the need to go through this back-breaking work and handles the water problem for you. 

  • Crawl Space Encapsulation 

Encapsulation is when the walls and floor of a crawl space are lined with thick overlapping sheets of polyethylene plastic. The vapor barrier that’s applied is air-tight, and they wouldn’t want anything to get stuck under the plastic sheets. It’s also a lot more difficult to properly adhere the plastic if there are things on the walls and floor, so they get rid of any water, and debris. They also fix any cracks and gaps along the walls and pipes that could be the source of any leaking. 

Rigid insulation panels also are recommended to be installed on the crawl space walls. These panels are much more durable and reliable than typical fiberglass insulation, which can easily succumb to moisture as well as harbor mold and pests. 

After the crawl space has been properly cleaned out, repaired, and insulated, the vapor barrier is applied. What this polyethylene plastic does is create a barrier between the outside world and the crawl space. It keeps water and moisture out, makes it more difficult for pests to get inside, and ultimately saves you from all the downsides that come with a humid crawl space. 

  • Dehumidifier 

Last but not least, a dehumidifier can be placed in order to fully deter humidity from ruining your crawl space. The dehumidifier industry professionals use for crawl spaces are not like the ones you might use in your bedroom. Due to their locations, exposure to precipitation and runoff, and their proximity to the land’s water table, crawl spaces experience much higher levels of humidity than any room in a house. 

Normal dehumidifiers are not equipped to handle the kind of humidity found in a crawl space. Not only will a normal dehumidifier fail to properly deal with the humidity in a crawl space, but you would also have to remember to manually dump the collected water. Dehumidifiers made specifically for crawl spaces are bigger and capable of reducing the humidity in a crawl space effectively. They send the collected water directly to the sump pump, so the entire process is automated and hassle-free. 

Other Less Effective Methods 

There are other methods used for waterproof crawl spaces. These methods are not as effective as the above three mentioned and the reason is very simple: They focus on repairing water damage in crawl spaces while ignoring prevention methods.  

  • Interior Sealants 

Interior sealants are a different method from encapsulation, which is an interior waterproofing method. When leaking in crawl spaces occurs because of cracks in the concrete, sealants are used to close the gap. Usually, epoxies are used as adhesive to cover the cracks, but urethanes are utilized as well. 

Using sealants isn’t a true waterproofing method because fixing small parts of the concrete isn’t going to fix the problem. Concrete deterioration is a sign of pitting, which occurs when the moisture in the concrete freezes and expands, resulting in the surface of the concrete flaking off. This can lead to cracks in the concrete. 

Sealants may temporarily stop the leaking problem, but they won’t stop the concrete from pitting and flaking. The concrete’s stability needs to be preserved, and the only way to do that is by making sure the inside of the crawl space is truly waterproofed.  

  • Exterior Alterations 

Exterior alterations are minimal alterations you can make to make sure not as much water infiltrates your crawl space. These alterations include pointing all downspouts away from the crawl space as well as extending them. Keeping flower beds away from the crawl space is another alteration. While these small changes are important and helpful, they alone are not enough to keep the moisture from the crawl space. Encapsulation and the installment of interior drainage, a sump pump, and dehumidifier are the only way to truly ensure your crawl space stays dry and clean. 

Crawl Space Waterproofing


The stack effect is something that affects most homes. Your crawl space plays a big role in how the air moves within your home, which also affects the quality of the air you breathe.  

  • Hot Air Rises 

In most homes, air comes in through an opening in the crawl space and exits through an opening in the attic or chimney. Hot air is less dense than cold air, thus it weighs less. Because it weighs less, it rises upward through the house until it leaves through the exit. The reason the air outside enters through the crawl space in the first place is that air will always try to go toward colder areas. The air outside is warmer than the air inside the crawl space, so that’s where it travels to and that’s how it gets in there in the first place. 

The speed at which this occurs depends on the weather. If it’s warm, the air in the crawl space will travel upward toward the house as soon as it enters. If it’s a bit colder, the air will stay in the crawl space for a bit until it gets warm enough to rise.  

  • How This Affects You 

The problem with the stack effect is that homeowners breathe in the air particles brought into their homes from the outside. The hot air that rises carries with it the dust and particles from, not just the streets, but the crawl space itself too. If the stack effect is going on in a home with a crawl space that has yet to be waterproofed, the air is causing serious harm to the inhabitants of the household. 

Not only does this kind of airflow affect your health, but it also affects your wallet. In the summer, all the hot air that travels from the crawl space to your home makes it harder for the AC to cool the room. You would need to have it turned on for longer periods just to reach a decent temperature, something that can be avoided with encapsulation.

Once you understand how crucial it is to waterproof your crawl space, your next question might be which method of waterproofing you should choose: encapsulation, interior drain, sump pump, and dehumidifier. The truth is, if you really want to ensure your crawl space remains dry and healthy for the rest of its existence, you need to choose all four options. Every single method has its own special purpose, and to use one without the other would be to leave the waterproofing job incomplete. 

North Carolina has a serious issue with water and moisture ruining the structural integrity of its buildings. Therefore, it’s important for you to use every method available to fully waterproof your crawl space.  

  • Why You Need Encapsulation 

Whatever method you choose to waterproof your crawl space, it can’t be considered true waterproofing if it doesn’t involve encapsulation. To encapsulate a crawl space is to close it off and prevent any water from getting it. Given the fact that North Carolina gets floods very frequently, you will want to make sure the crawl space is impermeable. Encapsulation also helps create an inhospitable environment for pests and animals, and it makes it more difficult for them to get inside. 

You can’t guarantee absolute dryness with just a sump pump and a dehumidifier, and this lack of dryness will end up deteriorating your crawl space. The sump pump will drain out the water and the big industry dehumidifier will handle the humidity, but your crawl space is still getting wet from time to time. Wood, concrete, and pipes suffer from constant exposure to water, so in order to protect them, it’s best to encapsulate the crawl space. 

  • Why You Need a Sump Pump and Dehumidifier  

Encapsulation does wonders to keep high amounts of water from entering a crawl space. That said, encapsulation does nothing to remove any water that could get in and the humidity it creates afterward. Sure, encapsulation will make going down your crawl space a lot easier and safer, so you could get rid of the water yourself. However, most homeowners don’t realize when their crawl space gets wet. Not to mention, it’s tiring work, especially if you have a very small crawl space you can barely squeeze through. 

No matter how well you think you’ve cleaned the crawl space and cleared out all the water, there will always be humidity in the air. Humidity is a lot more detrimental than you think, so once you’ve gone through the steps to waterproofing your crawl space with encapsulation, interior drainage, and a sump pump, complete the process and add a dehumidifier made for crawl spaces. 

Before the plastic vapor barrier is applied, the crawl space must be insulated. To insulate a space, contractors must fill in the gaps and crevices with a certain material that will either reflect heat or absorb it. This is used to control the flow of heat in a home. 

Crawl spaces do need to be insulated because the air inside interacts with the air in your home via the stack effect. There are two ways a space can be insulated. One form of insulation is better than the other, however, so read further so you can know to choose a contractor that provides the best option. 

  • Absorbent Insulation  

Fiberglass insulation is the industry standard when it comes to insulation. However, this doesn’t mean it’s the best or most effective insulation method. Fiberglass consists of extremely fine glass fibers. It’s a very soft material that is highly absorbent, so it absorbs heat pretty well. The only problem is that it absorbs moisture as well. 

When the fiberglass insulation in a crawl space absorbs moisture, it grows mold. As the fiberglass insulation absorbs more and more moisture, it gets heavier due to the weight of the water. Eventually, the insulation falls off, especially if it wasn’t placed correctly. Fiberglass insulation is still widely used in homes, but it has no place in an area as humid as a crawl space. Before hiring a contractor to waterproof a crawl space, make sure to ask what kind of insulation method will be used. 

  • Reflective Insulation  

The best kind of insulation for naturally humid areas are those with reflective tendencies. Reflective insulation panels and materials are those which control airflow in a space, not by absorbing heat, but by reflecting it. This keeps the heat inside the crawl space while still ensuring the actual insulation material stays dry and lasts for years. 

A good example of reflective insulation material is ExTremeBloc™. It’s made of polystyrene foam and it’s infused with graphite. An insulation material’s effectiveness is measured in terms of its R-value (also known as thermal resistance). Fiberglass insulation has an R-value of 2.2 to 2.7 per inch. Meanwhile, polystyrene foam insulators like ExTremeBloc™ have an R-value of 11. 

What Are the Consequences of Not Waterproofing a Crawl Space? 

Your crawl space’s condition isn’t something you should ignore. There are serious consequences to not waterproofing a crawl space that many homeowners are not aware of. Everyone knows crawl spaces for what they can do and what they are built for, but very few think about how they impact our lives on a day-to-day basis. Here’s how a humid crawl space affects your home.  

  • Structural Problems 

The humidity in crawl spaces affects the wood and concrete. With wood, humidity leads to fungus growth, which eats away at the wood. Concrete is also affected because it is a porous material, so it’s capable of absorbing water. Moisture expands when frozen, so when it expands past the concrete’s tensile limit, it displaces the concrete’s particles, causing surface damage. This can lead to more cracks in the concrete. 

  • Pests 

Pests such as rats, cockroaches, termites, and ants love damp, dark, secluded places. They can easily get into your home to eat and then return to the crawl space, where they will have plenty of water to drink and where they know they won’t be disturbed. Encapsulation will make it more difficult for these pests to get into the crawl space. 

  • Breathing in Bad Air  

Due to the stack effect, the air in the crawl space makes its way inside your house and becomes the air you breathe in every single day. This means that all the mildew, mold, pest droppings, and other harmful particles are things you take into your lungs when your crawl space is not waterproofed. This can lead to many health issues in the future.  

  • Raising Your Energy Bill 

Again, due to the stack effect, your unencapsulated crawl space is making your energy bill higher than it needs to be. Encapsulation and insulation mean that there will be no more open vents giving your HVAC system trouble getting your house to the right temperature. 

How Tar Heel Basement Systems Can Help You with Crawl Space Waterproofing 

Waterproofing your crawl space is an extremely important job, which is why you should call trustworthy people to do everything right. Since 2003, Tar Heel Basement Systems has been repairing the homes of Winston-Salem and Raleigh, NC. 

We understand how important proper encapsulation and insulation is for crawl space waterproofing, which is why we use a 20-mil vapor barrier instead of the standard 6-mil and expanded polystyrene foam insulation panels instead of fiberglass. This way, we’re able to ensure the highest quality repair job for every single one of our customers. We also understand how North Carolina’s climate affects crawl spaces. 

Don’t hesitate to contact us to schedule a free crawl space inspection and repair quote! We can’t wait to turn your property into a sturdy, safe home. 

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