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stack effect

The Stack Effect

The stack effect moves moisture from your crawl space into the rest of your home, putting its value and structural integrity at risk.

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Crawl space flooding is its own form of trouble, but it’s not the only force that can plague your home. As the humidity in your crawl space rises, your home may fall victim to the stack effect. 

The stack effect can move the moisture in your crawl space through the rest of your house. You can start to see signs of moisture damage in the upper levels of your home as a result. 

The good news is that if you want to get ahead of the aesthetic and structural damage that the stack effect generates, the professionals serving Kansas City, Moberly, St. Louis, and Springfield, MO, can help. 

stack effect

Understanding the Stack Effect 

The term “effect” makes the stack effect seem like a force that actively works against the structural integrity of your home. In many ways, it is, though it is not “active” in the same way that pests are active. Instead, the stack effect is a condition in a home describing the behavior of air based on its density. 

Warm air is less dense than cool air. As a result, warmer air tends to rise to the top of a home. However, if the air in your crawl space takes on a significant amount of moisture, the density of your air won’t be as readily determined by its temperature. Instead, it will be determined by the amount of moisture it bears. 

You’d think that moisture-heavy air would stay in your crawl space. This, unfortunately, is not the case. As moist air fills up your crawl space, it can leak out, rapidly filling up the rest of your home with unwanted humidity as a prelude to additional problems. 

In other words, the stack effect is not always a force that works against the integrity of your home. Under normal conditions, it keeps your crawl space cool and the upper levels of your home warm. When you find yourself dealing with crawl space damage, the stack effect becomes a force that drives moisture into the nooks and crannies of your home, raising your electric bill while also damaging your unprotected porous materials. 

Getting Rid of the Stack Effect 

There is no getting away from the stack effect. No matter what steps you take, the warmer air in your home will always rise to the top of your home. However, if you work to eliminate the excess moisture in your crawl space, you can prevent wood rot and other moisture-affiliated damage from appearing in the rest of your home. 

You can do this through a few different means, most often with help from the professional contractors serving Kansas City, Moberly, St. Louis, and Springfield, MO. If you find yourself contending with unwanted moisture in the upper levels of your home, you can schedule a home inspection and related consultation. You’ll have the chance, once your inspection is over, to look over a free services quote detailing what repair and waterproofing services may best protect your home from unwanted moisture. 

The Stack Effect and Symptoms of Damage Throughout Your Crawl Space 

The stack effect isn’t easy to track if you don’t know what to look for. The good news is that most homeowners can detect this kind of damage once they know what to look for. With that in mind, homeowners concerned about the effects of the stack effect will want to look out for: 

  • High levels of humidity throughout your home – Increased humidity in your crawl space is one thing. Increased levels of humidity on your first and second floors are another. Crawl space humidity is a source of concern because it makes it easier for mold to take root and for your supports to give way. Humidity in the upper levels of your home puts your belongings at risk while also compromising more of your home’s essential supports. In short, increased levels of humidity in the upper levels of your home suggest that the damage you’re dealing with has gotten worse over time. If you notice the hygrometer or humidistat ticking upward, you’ll want to reach out to area professionals as soon as possible to discuss repairs. 
  • Unpleasant smells – Moisture doesn’t tend to accentuate pleasant smells. As humid air circulates through your home, you’ll notice your upper levels smelling damp. This scent tends to be pervasive; you can’t easily cover it up with any kind of air freshener. Instead, the continual presence of this scent can make your home feel consistently less clean than it is. 
  • Mold – You deal with different kinds of molds on a regular basis, even if it doesn’t feel like it. There are some molds, however, that are more dangerous than others. Allergenic, toxigenic, and pathogenic molds, as opposed to the molds you find on bread or food, can better take root in your home when they have access to a regular supply of moisture. The stack effect can ensure that any mold spores still hiding out in your HVAC system have just that. In turn, these molds can trigger respiratory problems for your family, even if you don’t have a history of said problems to contend with. 
  • Damaged insulation or structural supports – Your insulation does two jobs in your home: It keeps temperatures consistent and limits the amount of moisture that makes its way indoors. Unfortunately, many insulating materials are relatively fragile. Long-term exposure to the stack effect and its related moisture can see these materials transform into mold incubators. As insulation starts to take on damage, it can also put your home’s structural supports under additional stress, speeding their decay. 
  • Standing water – As mentioned, the stack effect spreads unwanted moisture throughout the whole of your home, not just your crawl space. Normally, that moisture remains in its gaseous form and gets absorbed by your home’s various porous materials. If those materials end up oversaturated, you may start to notice standing water in the upper levels of your home. If the damage to your property reaches this degree of severity, you’ll want to sit down with an area contractor to discuss just how extensive your home repairs may have to be. 

Repairing Stack Effect Damage in Your Crawl Space 

It’s never a good idea to try and repair crawl space damage caused by the stack effect on your own. The professional contractors serving your area can take the wheel instead. Together you can inspect both your crawl space and the rest of your property to better address the scope of your home’s damage. 

With a better idea of how much damage they’re dealing with, professionals can then recommend your ideal repairs. Crawl space inspections usually involve the following steps: 

  • Early inspections – Crawl space inspections don’t begin in your crawl space. Instead, they begin at the crawl space’s entry point. Your crawl space needs to be at least two feet wide and 18 inches tall. If your crawl space’s entry is smaller than that, or if it’s obviously unsafe, the professionals in your area will not be able to proceed with the inspection for the sake of their own safety. You’ll need to invest in supporting and otherwise altering your crawl space entrance before future inspections can continue. However, if it appears that your crawl space’s entrance has been damaged due to the presence of excessive moisture, professionals may be able to discuss potential repairs with you right off the bat. 
  • Superficial inspections – Provided that a professional can make their way into your crawl space, an inspection will proceed onto its superficial stage. This stage sees professionals look over your crawl space for immediate and glaring signs of damage, including sagging insulation, bowing walls, or problematic floor joists. Professionals will also keep an eye out for mold clusters that have grown to dangerous sizes or utilities that appear to be in immediate danger. If a professional is able to spot any damage of this kind without looking too hard, they can reconvene with area professionals to discuss potential repairs. 
  • Full Inspections – If there’s nothing immediately wrong with your crawl space, professionals will move in further. A full inspection sees area professionals look over your supports, joists, floor, and surrounding soil for signs of concentrated water damage. If professionals are able to identify burgeoning damage or damage that may have leaked up into your crawl space from your foundation, then they’ll forgo the rest of the inspection to discuss potential causes and repairs with you and their teams. 

Once professionals complete their inspection of your crawl space, they can more soundly recommend certain types of repairs. Cracks, for example, beget filling and potential foundation repairs if they are serious enough. Bowing walls may benefit from wall support systems. Your options are going to depend on your damage, so make sure to stay in consistent contact with your team of professionals so that you know what to expect. 

Stack Effect


There are a few different forces that can work against the structural integrity of your crawl space and, subsequently, the rest of your home. More often than not, these forces work together, meaning if you don’t treat one, the others can cause just as much damage to your property. Some of the most pervasive forces working against the integrity of your crawl space include: 

Hydrostatic Pressure and Friends 

Hydrostatic pressure is one of the most persistent forces to work against the structural integrity of your home. As moisture gathers around the perimeter of your home and crawl space, it can force the structural materials you have in place to change size and temperature on a molecular level. In doing so, that moisture can cause a significant amount of stress for your supports. Over time, that stress can cause cracks to develop in the compromised materials, subsequently allowing additional moisture to make its way into your home. That moisture can begin to build up indoors to the point where it may travel through the rest of your home via the stack effect. 

That said, hydrostatic pressure does not work alone. Tree roots, pests, and even faulty construction can all contribute to higher-than-normal moisture levels inside of your home. If, for example, hollows have started to appear beneath your home, contractors may be able to trace your existing damage to uneven crawl space sinkage. 

The Stack Effect 

As mentioned, the stack effect is somewhat inescapable. It’s only a negative force within your home, however, if you find yourself contending with crawl space damage. A crawl space that’s overwhelmed with moisture will spread that moisture throughout the rest of your property, compromising the structural integrity of your supports. 

The damage you can see in a home impacted by the stack effect varies. If you manage to catch your crawl space damage early on, the problems you see in the rest of your home may be minimal. Comparatively, if you fail to repair your crawl space, then you may start to see your drywall dissolve, mold clusters appear, and your wooden or otherwise unprotected supports fall victim to rot. 

If you’re cost-focused or alternatively interested in trying your hand at some DIY, you may be tempted to repair your crawl space on your own time. While the enterprising homeowner may see stack effect damage and related crawl space problems as a challenge, they are more than that. This kind of damage can have a long-term impact on both your finances and your home’s value, not to mention its overall structural integrity. Trying to repair your crawl space on your own without compromising those things is an all but impossible task. 

The Cost of DIY 

Many homeowners try DIY crawl space repairs in an attempt to save money. This, unfortunately, rarely works in the homeowner’s favor. To get started, homeowners have to purchase the tools and materials they need to repair their homes. If you don’t know what kind of tools you’re looking for, you may make mistakes during this period that blow your repair budget. Many of the tools you bring home may also be single use, meaning that you may never have a reason to use them again. 

Professional contractors already have access to the tools and materials they need to restore your crawl space. When you work with professionals, you can write the initial cost of tools and materials out of your budget in favor of costs like time. 

Potential Mistakes and Your Home’s Value 

Homeowners who attempt to repair their crawl spaces on their own can often make mistakes. While mistakes are a part of the learning process, you don’t necessarily want to be learning how to be a better repair person while working on your own property. These mistakes, after all, can exacerbate the damage that’s already been done to your home. They can also actively devalue your property. 

For example, if you DIY a crawl space repair solution, you may assume that your water-related problems are solved. If you’ve just covered the problem up or if you’ve addressed a symptom instead of the cause, you’re in trouble. The damage in your crawl space will worsen over time to the point where you may lose up to 30 percent of your home’s market value. 

The professionals who you invite out to your home will recommend different means of crawl space repair depending on what problem you’re contending with. As such, the nature of your crawl space’s damage is going to have a significant say over the kinds of repairs you invest in. That said, professionals not only offer you the chance to repair your crawl space’s damage but to eliminate the stack effect and prevent future moisture damage across your property. To do so, professionals in your area can recommend: 

Initial Repairs 

You never want to invest in crawl space waterproofing measures before you’ve repaired the source of damage therein. With that in mind, talk with area contractors about what kind of repairs your home needs. Some of the most common sources of water and unwanted moisture in a crawl space include joint cracks and an unprotected perimeter. 

Note that the repairs you need to invest in may involve a revamping of your crawl space. If you have utilities in your crawl space, professionals may recommend new insulation installation specifically to keep those utilities safe. Be sure to discuss your budget with area professionals ahead of time so you can explore all your crawl space repair options without stressing out over all your repair and reconfiguration options. 

Addressing the Stack Effect with Home Waterproofing 

Only once professionals have addressed the source of damage in your crawl space should you go about discussing your potential waterproofing measures. These measures will keep unwanted moisture from settling in your crawl space, meaning that they’ll mitigate the worst of the stack effect no matter how much rain your area gets. 

Some of the most common crawl space waterproofing methods include: 

  • Encapsulation with a vapor barrier and vent covers 
  • Interior drainage and sump pump installation 
  • Dehumidifier installation 
  • Waterproof insulation installation 

Note that you always have the option to use these waterproofing measures in pairs as opposed to singularly. If you think your crawl space might benefit from stacked solutions, be sure to discuss the options that best apply to your home with your team of contractors. 

Waterproofing Your Crawl Space 

After professional contractors finish repairing damage in your crawl space, they can waterproof it. The waterproofing measures that see the most use in Kansas City, Moberly, St. Louis, and Springfield, Missouri, include: 

  • Encapsulation with a vapor barrier – Crawl space encapsulation uses a thick, plastic-like vapor barrier to cover the crawl space wall and floor. They are designed to prevent moisture in its liquid and gaseous forms from entering your crawl space. These barriers can also keep out most standard gases, making them an excellent safety addition to any home. Encapsulation also further seals off your crawl space with vent covers to prevent outside air and moisture from infiltrating the crawl space. 
  • DehumidifiersDehumidifiers are not all-encompassing waterproofing solutions. Instead, professionals will often pair dehumidifiers with vapor barriers or other forms of waterproofing to reduce the moisture in your crawl space or in other parts of your home. 
  • Waterproof insulation – Thermal insulation already works to regulate the temperature in your crawl space. Waterproof thermal insulation creates a physical, hydrophobic barrier between your home and unwanted moisture. 
  • Drains and sump pumps – Interior drains and sump pumps are cousins that work together in keeping water out of your crawl space. The interior drainage system collects any water that leaks in through the crawl space, and the sump pump system removes it from the crawl space. 

You always have the option to use these home waterproofing measures in tandem with one another if you believe that your crawl space’s water damage has been particularly severe in the past. 

Get In Touch with Local Professionals 

When you invest in crawl space repairs and projection, you do more than just keep unwanted moisture out of that space. Waterproofing measures and crawl space repairs can both prevent the stack effect from spreading moisture into other parts of your home, including your house’s upper levels. 

The professionals serving Kansas City, Moberly, St. Louis, and Springfield, Missouri, can help you not only identify symptoms of the stack effect but address them as well. Reach out to the team at Foundation Recovery Systems to schedule a free inspection, and you’ll have the chance to look over a free quote detailing what repairs or protective measures your crawl space may benefit from. 

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