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Basement Wall Vapor Barrier

In Knoxville, Tennessee, mold and leaks can be a thing of the past with WallSeal.™ This vapor barrier can stop basement humidity and other problems related to it.

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Even though basements are known for being humid, it doesn’t have to be that way. There is no reason you should settle for having a moldy, damp basement when you can clean up the area and keep it dry with a vapor barrier. If you’re a homeowner in Alabama or Tennessee and you would like to keep your basement tidy and dry, AFS Foundation & Waterproofing Specialists offers you WallSeal™ for basement waterproofing. 

WallSeal™ is a vapor barrier system meant to stop moisture from entering a basement. It’s made of a rigid plastic that is completely impervious and keeps water vapor from permeating through the basement walls. Our vapor barrier material has a multitude of advantages, including: 

  • Flexibility, for application on irregular surfaces 
  • Never peels or flakes 
  • Washable 
  • Mechanically applied 
  • Custom cut to fit your basement perfectly 
  • Built-in anti-microbial protection 

Vapor retarding wall liner for wet basement waterproofing

WallSeal™ is perfect for homeowners with basement humidity problems and for those that wish to give their basement a cleaner look. Vapor barriers are completely white and smooth, so applying them to basement walls makes the space look bigger, brighter, cleaner, and complete. Upgrading your basement with a vapor barrier also raises the property value of your home, so it’s something to consider even if you won’t live there for long. Not only would you be selling a home with a visually appealing basement, but also one that has no moisture problems. 

How Moisture Enters Your Basement 

Many homeowners believe that just because they don’t see standing water, their basement is dry. However, if you notice a musty smell and mold, your basement might be suffering from some major humidity problems. 

It may seem odd that basements are so humid despite being enclosed, but you must remember that basements are built either completely or partially underground. The soil under your property is saturated with moisture for almost the entire year. This is especially true for basements surrounded by expansive soils. 

Because of their clay content, expansive soils retain a lot of water. Certain parts of Alabama and Tennessee, like Huntsville and Knoxville respectively, are covered in expansive soils. Every time it rains or whenever the snow melts during the winter, the soil on your property absorbs and holds on to that moisture. 

Other areas with sandier soil types, like Mobile, Alabama, or Nashville, Tennessee, still have basement humidity problems despite having well-drained soils. If the basement was built near the zone of saturation, there is still a way for the water vapor to reach the basement. The zone of saturation refers to the area underground where the soil is continuously saturated with water. During rainy seasons, the water table (which indicates where the zone of saturation begins) rises as the soil absorbs an excessive amount of rainwater. 

The concrete that makes up the walls of your basement is porous. The water vapor from the moisture in the saturated soils easily permeates through the basement walls and causes humidity. This is why your basement is so humid despite no leaking or flooding problems. 

How Vapor Barriers Protect Your Basement 

The vast majority of homeowners will agree that a flooded basement is a lot worse than some moisture in the air. Therefore, many don’t see the need or have the urgency to put up a vapor barrier on their basement wall. What they may not know is that humidity in a basement can be just as troublesome as standing water. 

Humidity causes mold growth, and because of the stack effect, the moldy basement air pollutes the air throughout your home. Structural problems, health risks, and a whole list of other issues come because of a humid basement, so it’s best you do something about it. Because vapor barriers can block out moisture, they save you a lot of money and protect your family from mold-related health problems. 

  • The Stack Effect  

The stack effect refers to the way air travels around your home. Warm air will always try to move to where it’s colder, so the warm air from the outside moves into your basement and rises to your home. Because of this, all the musty, warm air that is in your basement infiltrates the upper portions of your home. 

Odd smells and dusty basement air might seem like the least of your worries, but it gets worse. Humid air is a lot warmer than cold air, so the humidity that rises throughout your home is actually costing you money. Your AC usage would be a lot more efficient if it didn’t have to cool down a house full of humid air. If your basement is dry and cool, the rest of your home will be as well. 

  • The Problem with Mold 

Humidity will promote mold growth in your basement. Mold is a microorganism that needs food and water to survive, just like we do. It grows on things that contain organic material, like wood and concrete. 

Concrete has salts and minerals that the mold feasts on, which is why a moldy basement wall is a clear sign that you have a humidity problem. Mold eats away at anything or any material it grows on, so your concrete will deteriorate with time if mold is allowed to grow on it. The concrete in your basement is what makes up your foundation, so if mold slowly causes structural problems, you’ll be paying for foundation repairs soon enough. 

Mold growth on wood will also cause structural problems. As the mold destroys the wooden floor joists and supports, they will be unable to support your floor properly. It will begin to sag and you’ll feel the floor sinking under you every time you step on a spot with weak, moldy joists. 

Your home’s health isn’t the only thing at risk when you have a moldy basement. Because of the stack effect, all the mildew in your basement rises along with the warm air in your home. Mold can trigger allergies and irritate your lungs, eyes, throat, and skin. It’s incredibly dangerous for those with a weak immune system. Long-term exposure to mold can permanently damage a person’s respiratory system, so making a one-time investment in a vapor barrier will protect you and your family from potential health problems. 

How Vapor Barriers Are Installed 

Vapor barriers are incredibly easy to install. However, your basement might need some work before they can be applied. If your foundation has problems, this will need to be addressed. Foundation settling, cracked or bowing walls, and broken basement windows will reduce the effectiveness of the vapor barrier.  

  • The Repairs  

Remember, the vapor barrier stops water vapor from humidifying the basement, but it cannot make the basement fully waterproof. Sump pumps, insulation panels, dehumidifiers, and internal drainage systems all work in tandem to keep your home’s sub-level dry, not just the vapor barrier. Without these repairs and waterproofing measures, water will leak into your basement and cause the same problems as the water vapor. 

A drainage system that works incredibly well with WallSeal™ is our BasementGutter™ Interior Drain System. Any water that gets into your basement will run down the vapor barrier and into our BasementGutter™ interior drain system. Together, these two waterproofing solutions save you from having to deal with a wet basement.  

  • The Application Process 

Once your basement has been sorted out, the vapor barrier can be applied. This process takes a day or less, so it’s very quick and won’t take up much of your time. WallSeal™ is a plastic sheet that can be cut into pieces so that it’s custom fits into your basement’s parameters. Once everything has been measured and cut, the contractors will apply the sheets one by one, overlapping them on one another so that no area is left uncovered. The seams are fastened together with drilled in plastic ligatures to make sure the sheets never fall off your wall. 

  • After Application  

Once the basement walls are lined with the vapor barrier and no other installations need to be done, you can use your basement as you normally would. You don’t need to wait for the vapor barrier to dry since it is mechanically linked to the walls. Because a vapor barrier does not take up any space, you can continue to store things in your basement. 

As a matter of fact, with a vapor barrier, you have more storage possibilities than before. Because your basement will no longer be humid (assuming you have other waterproofing measures in place, like a dehumidifier and drainage system), you can store items that would otherwise erode in humid environments, like bikes and electronics. 

Basement Vapor Barriers vs. Waterproof Paints 

Waterproof paints are heavily marketed toward homeowners as a workable solution for basement humidity. Using waterproof paints is a popular route to take for many homeowners who don’t wish to pay for professional installations. Unfortunately, like most DIY home improvement solutions, waterproof paints do not protect your basement from water vapor.  

  • Where Waterproof Paints Fail 

Waterproof paints are paints based on oil or latex that bond to a surface to deter moisture penetration. Because of the materials used in these paints, however, mold growth is possible on a wall that has been coated with waterproof paints. Mold eats organic matter, so any paint that contains organic material will still see mold growth. 

Waterproof paints don’t stop outside moisture from permeating through the walls. Moisture can displace the salt and mineral content in concrete and bring them to the surface. This causes the salts to form in clumps at the surface of the concrete, a process known as efflorescence. The pressure of the efflorescence buildup causes the paint coating to peel right off. 

Waterproof paint is a short-lived solution that is only slightly effective for a few months before completely losing its efficiency within two years. As you can imagine, continuously painting your basement and watching as mold slowly grows on your walls isn’t a productive way of solving your humidity issue. Instead, it’s a lot simpler to apply a vapor barrier along your wall and never have to worry about basement dampness again. 

Basement Wall Vapor Barrier


When talking to experts about waterproofing their basement, a lot of homeowners question the need for a vapor barrier, especially if they say yes to a dehumidifier. After all, why apply a vapor barrier to a wall when the dehumidifier will absorb all the moisture anyway? On that note, why have a dehumidifier if there won’t be any moisture in the basement anyway due to the vapor barrier? 

The answer to those questions is that dehumidifiers and vapor barriers serve vastly different functions, which is why they are needed together. 

  • What Dehumidifiers Can and Can’t Do  

Dehumidifiers are placed in basements to make sure that the moisture levels in the space stay adequate. Dehumidifiers make sure that any microorganisms with the potential to grow into mold cannot get the moisture they need to survive. Even dry rot, which can pull in moisture from afar, has trouble thriving in basements with a dehumidifier. 

What dehumidifiers can’t do, however, is stop moisture from permeating through the concrete and cause efflorescence and weaken the concrete’s structure. If water leaks through the basement window, it will have to work overtime to get rid of all the moisture that was absorbed by the concrete. Overtaxing a dehumidifier by not controlling the amount of moisture that enters a basement decreases its lifespan. 

  • What Vapor Barriers Can and Can’t Do 

Vapor barriers block all moisture from permeating through to a basement. They keep the space dry, not by absorbing the humidity in the air, but by preventing it altogether. If any water makes its way into the basement, it prevents it from getting absorbed by the concrete, effectively preventing mold growth on the walls. In fact, it directs all water toward any parameter drainage system you have installed in your basement. 

What vapor barriers can’t do, is get rid of moisture that is already in the basement. Just because the vapor barrier is in place, doesn’t mean that water can’t ever get through. Basement windows, damaged sump pumps, leaking pipes, and broken heaters or washing machines can all cause leaking problems that increase the humidity in the basement. Once that humidity is there, problems will arise.

Once you understand what a vapor barrier can do for your basement, you might get the urge to cover the entirety of the space. While it is possible to do so, it isn’t often done by contractors for several reasons. 

  • Why It Isn’t Always Done  

The reason contractors only apply vapor barriers to basement walls is that it isn’t necessary to cover the ceilings as well. Applying barriers to a basement ceiling is not efficient because the basement’s humidity mostly comes from the soil, not from the home itself.  

Vapor barriers are thick and strong, but they can still tear open. If a basement floor is covered in a vapor barrier, as items are moved around and homeowners walk on it, it will wear down the sheets and shorten the lifespan of the material. It could even break open if a sharp enough object is dragged along the floor. 

  • What You Can Do Instead  

If your goal is to completely waterproof your basement so that it never floods and the humidity levels stay low, you don’t need to completely cover your basement. Besides a vapor barrier, there are other basement waterproofing solutions that can be invested in that work well with vapor barriers. 

Talk to your local foundation waterproofing experts about improving the insulation in your basement for one that has no absorbent properties. Install a sump pump, and if you have one already, consider getting a second sump pump for better drainage efficiency. An interior drain system can drain water out, and a dehumidifier will ensure that the air is forever fresh and dry. 

Vapor barriers are made of a special material that guarantees basements full protection from water vapor. 

  • The Material 

Vapor barriers are made of polyethylene, which is a thermoplastic polymer. Thermoplastics have a high molecular weight, which makes them molecularly denser than normal plastic. Because of their density, they are a lot better at blocking off smaller particles like water vapor. Polymer, on the other hand, has large molecules, excellent for stopping smaller water particles in their tracks. 

Plastic is a synthetic material made up of different ingredients. Plastic is porous and its molecules aren’t dense enough to stop water. It may seem like a good waterproof material because, to the naked eye, it blocks liquid from saturating other materials. What we can’t see, however, is the small water particles permeating through the plastic over time, so it is not a good waterproofing material for perpetually humid places like basements. 

  •  The Effectiveness 

Polyethylene is among the most durable plastics in the world. It can withstand years of moisture exposure without breaking down. Vapor barriers like WallSeal™ have anti-microbial protection specifically meant to discourage mold growth in the material. It’s specially made for waterproofing purposes, making it perfect for use in basements. 

The same cannot be said for normal plastic. Plastic sheets are not designed with basement waterproofing in mind, so they don’t make good vapor barriers. Mold is also capable of growing on plastic sheets. Plastic can harbor bacteria, which later turns into nutritious food for mold. Overall, plastic sheets should not be used for basement waterproofing. 

Call AFS Foundation & Waterproofing Specialists for Basement Vapor Barrier Installation 

Say goodbye to the mold and humidity in your basement. If you live in Alabama (Mobile, Birmingham, Huntsville) or Tennessee (Nashville, Chattanooga, Knoxville), AFS can install a vapor barrier in your basement. We’ve been providing homeowners with innovative, enduring waterproofing solutions since 2000 and have established a reputation for being the best foundation experts in the area. 

Give us a call or fill out our online contact form so we can schedule a free inspection with one of our knowledgeable field experts. You’ll be given a quote and a complete rundown of everything you need to get rid of the dampness in your basement. So don’t hesitate—a dry basement awaits. 


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