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Crew installing vapor barrier for crawl space encapsulation

Crawl Space Repair

More than half of the air you are breathing in your house comes from the crawl space. So, whatever is in the crawl space, like mold and allergens, also is in the rest of your home and affecting you.



The biggest culprit of crawl space issues that leads to these issues has to do with the way your home was constructed.

As warm air rises in a home, it leaks out of the upper levels. New air must enter your home to replace the air that has escaped. In fact, in a tight home, about half of the air escapes each hour out of the upper levels. This creates suction at the lower levels to draw in replacement air. In older homes, the air exchange rate can be as high as two exchanges per hour.

What this stack effect does is create airflow in your home from bottom to top. So air from the crawl space is drawn upwards into the first floor living area and then into the second floor. Of course, it dilutes with other air in your home, but building scientists say that up to 50% of the air you breathe on the first floor is air that came from your crawl space.

Therefore, whatever is in your nasty crawl space air (mold spores and humidity) is in the living area of your home and could negatively be affecting your family. Whether you spend none or any time in your crawl space the air is still traveling upwards into your home. If there is mold or mildew in the crawl space, there are mold spores floating around upstairs that your family is breathing in.

So this idea that we put in crawl space vents and expect that air will flow in through vents on one side of the house and out through the vents on the other side, does not happen. What actually happens is air enters the vents in the front, enters the vents in the back, and enters the vents on the sides of the home and then it goes UP!


As cold air enters your crawl space, the stack effect carries that cold air throughout your home. What does this mean for your home?

The stack effect also allows dust mites, mold growth, and nasty odors to travel through your home into the air you and your family breathe. It also will create cold floors and a cold environment within your home, which causes you to use your home’s heating system more heavily, causing high utility costs. In order to keep your home warm, and the air you and your family breathe clean, it is important to keep your crawl space healthy and dry.

Many factors cause a damp and cold crawl space, like open vents, condensation, and water vapors. Rumors have it that insulation to your floors or roof of your home’s crawl space will help keep your home warm during the colder months, and is partially true; however, insulation ignores the real problem of moisture in your crawl space and will only be ruined by the moisture.


Crawl space humidity has been plaguing homes in North Carolina and Virginia since the first day they were built.

As the humidity levels rise in crawl spaces, moisture condensates on the surfaces, leading to serious problems in your home. These problems can lead to health issues and the need for expensive repairs.

Most of the problems traditionally associated with damaged, rotting crawl spaces are due to basic flaws in the ways that crawl spaces were designed.

When the frame of your home was first built, it was a large wooden box, with few, if any, holes in it.

Then came the other contractors. As plumbers, electricians, HVAC workers, and countless other professionals began to work in your home, they began to cut channels in your walls and floors. Pipes, wires, cables, ducts, and other things were passed through, and your home’s construction was completed.

Then, over time, your home began to expand and contract. The once-tight seams began to warp slightly, and more crevices and openings appeared. There are a lot of openings that can develop between your first floor and your crawl space!

In your home, warm air rises, leaving through your attic and upper floors. As this happens, a vacuum is created on the lower floors. Air from the outside — and from your crawl space — is pulled upwards to fill the space.

If you have crawl space vents, they will also become part of the air movement in your home. As air is pulled out of the crawl space and up into the home, new air will be pulled in through these vents.

Here’s the key point: If the air outside is wet or humid, then your crawl space vents are bringing in moisture.


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    The biggest culprit that leads to these issues has to do with the way your home was constructed. While it is outdated, building code traditionally has called for crawl spaces to have open vents for air drying purposes. This sounds all well and good, but in reality, it is harmful to your house and your family. 

    Open vents are invitations for outside air, water, pests, and rodents to come inside and wreak havoc on your crawl space and home. Would you feel comfortable knowing these nuisances are under your loved ones’ feet?  

    More than half of the air you are breathing in your house comes from the crawl space. So, whatever is in the crawl space, like mold and allergens, also is in the rest of your home and affecting you.


    Think of your house like a chimney – air enters at the bottom, rises through the structure, and is expelled at the top. Air pressure also is a factor. Air flows from areas of high pressure to areas of low pressure. When there is a greater difference between indoor and outdoor temperatures, the more significant this airflow becomes. (Source: Fine Homebuilding) 

    While you can’t see airflow, it might help to see this in action to get a better understanding of the stack effect. The Cold Climate Housing Research Center has several YouTube videos, including ”Your Nothern Home: Stack Effect” that illustrates the stack effect. 

    Here are some other problems that result from open crawl space vents and the stack effect: 

    • Water intrusion
      Any kind of water in your crawl space – whether it comes from the ground, through walls, through vents, or from plumbing leaks – is a problem. Standing, leaking water invites pests and promotes mold growth, and it can weaken wood and corrode metal support systems.
    • High Humidity
      Along with leaking water, humidity is a major issue affecting homes. Humidity above 50% contributes to mold, unpleasant odors, failing support systems and more.

      High relative humidity and moisture is common in crawl spaces. These conditions promote mold growth, especially on organic materials like wood and insulation. Any crawl space moisture also can enter other areas of the home through wall, ceiling and floor cracks, and contribute to mold growth there. (Source: EPA)

    • Wood Rot and Sagging Floors
      You’re probably well aware of how oppressive the North Carolina humidity can be. Your home is no stranger to its effects, either. When water, moisture, and humidity are present in the crawl space, this is a recipe for structural issues. As wooden beams and other supports are exposed to water and humidity, they can easily rot and begin to sag. These systems will no longer be able to support the above floor, and the floor will develop soft, bouncy spots and begin to sag.
    • Energy Loss
      Open crawl space vents allow hot air to enter during the summer, causing your air conditioner to work overtime to cool the rest of the house. And the same happens with cooler wintertime air that makes your furnace struggle to keep up in maintaining a comfortably warm living environment. Floors often may feel cold because of the cooler air from the crawl space underneath. Rather than wasting money on high energy bills, close the crawl space vents for better energy efficiency! 

    Here are a few additional questions we hear from homeowners like you, wondering what they should do about the issues they notice with their crawl space: 

    • Should you seal a crawl space? 
    • Is crawl space encapsulation a good idea? 
    • Does my crawl space need insulation? 
    • Do I need a vapor barrier in my crawl space? 
    • Should I dehumidify my crawl space? 

    The answer to all of them is, you guessed it, YES! 

    But before you grab your keys and head out to your local home improvement store, pause for a moment. You may be very handy, but crawl space repair projects are not meant to be knocked out by you and a friend in a weekend. We have seen what can happen with do-it-yourself work, and it’s not always pretty. Especially when it comes to real estate transactions, things like quick fixes could raise red flags and you’d have to spend more time and money to fix them. 

    So, don’t waste your energy and finances on temporary quick fixes. Make sure your crawl space is fixed the right way the first time by a reliable contractor with trustworthy solutions. 

    Especially after learning a little more about how dangerous and disgusting crawl spaces can be, aren’t you motivated to take charge and clear this area of unhealthy nuisances? There are so many ways that having a cleaner crawl space will benefit you and your family. Here are just a few perks: 

    • Health and Quality of Life
      It’s possible that your home could be making you sick. By cleaning out and sealing the crawl space from outside nuisances, you are taking a huge step in ensuring the health and safety of your home and your loved ones. A mold-free, allergen-free, pest-free crawl space allows you and your family to breathe easier. Steps like installing a dehumidifier also will help with better air quality.
    • Structural Integrity
      Crawl spaces with water intrusion and humidity that impacts the support system under the house are not structurally sound. When you address the water and shore up the supports with more sturdy options, your house will, in turn, be more structurally stable.
    • Energy Efficiency
      A crawl space that is properly sealed in insulated does not require as much energy usage. Unvented crawl spaces are estimated to use 15 to 18% less energy for heating and cooling while reducing humidity by over 20% when compared to vented crawl space homes. (Source: Hunker – Code Requirements for Crawl Spaces)
    • Functional Space
      A crawl space that is clean, dry, and properly sealed and insulated is an ideal area for storage. You’ll no longer have to worry about any of your belongings being damaged by water, mold or pests.
    • Real Estate Value
      Your home’s appraisal value can depend on a variety of factors. However, structural integrity, water issues, and other problems such as with crawl spaces are important areas you need to be aware of. If you are selling your house, you must fill out the State of North Carolina Residential Property and Owners’ Association Disclosure Statement to the best of your ability. North Carolina law requires sellers to identify any known defects in their property before a purchase contract is signed. This sets clear expectations so there are no surprises for the buyers, and it helps protect you, the seller, from litigation. (Source: Nolo

    This is by far the most common question we hear. And rightly so. Your home is a significant investment, and you want to make sure you’re investing in the right kinds of solutions that will work right the first time to effectively protect your home. 

    To give you an idea, HomeAdvisor states the average cost of crawl space repair is $6,000, with a wide range depending on the exact problem, size, accessibility and what’s being removed. 

    That being said, if you call in to ask or search our site with this question in mind, you aren’t going to get a clear idea right off the bat. We understand how frustrating it can be to not get a straight answer right away. But there is a lot to consider when talking about repair work. 

    First off, it’s important for an inspector to physically visit your house and look at the crawl space. It’s not fair to you to just give a ballpark estimate without seeing what’s going on. 

    The cost also depends on specifics like the square footage to determine how much material will be used, as well as the extent of any damage. 

    Every home is different, and each project requires different solutions.  So, what worked for a friend or family member might not necessarily be what your home needs. 

    Be sure to have an open and honest discussion with your contractor of choice regarding cost. Most companies should be able to take your budget into consideration and work with you on payment options.  

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