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The Stack Effect: Everything You Need to Know

stack effect

The stack effect is a phenomenon that causes warm air to rise from the lowest to the highest point of a building due to variances in temperature and moisture levels. As the warm air rises, it creates a negative pressure at the building’s base, pulling in cold air to fill the void. This phenomenon is relatively common in homes with a basement or crawl space and can affect air quality and utility costs in a household. 

Home contractors and designers are generally aware of it, but most homeowners have no idea what it is. Let’s explore what the stack effect is, how it affects your home, and how to mitigate the issues associated with it. 

Understanding the Stack Effect 

Generally, the nature of heat and airflow is a confusing topic for most homeowners. Those in the home improvement sector believe that warm air rises, but heat does not. So, how can warm air rise and leave the heat behind?  

Warm air is typically lighter than cool air. When the air in your home warms up, it rises to the building’s upper levels. This reduces the pressure in the lower areas, allowing cold air to get in through windows, doors, and other openings.  

The stack effect is common during winter when the air outside your home is colder than your indoor air. During this period, the stack effect causes warmer air and your conditioned indoor air to rise. Cold air from outside seeps into your home’s lower areas to fill up the void left by the warm air.  

For every cubic foot of warm air that leaks out, another cubic foot of cold air leaks in to replace it. The greater the leaks within your house the higher the temperature fluctuations. 

Factors That Contribute to the Stack Effect 

Some of the conditions and factors that give rise to the stack effect include: 

Ventilation and cracks or gaps in the building: Cracks and gaps provide an entrance for outdoor air and an exit for conditioned indoor air. If these openings exist in your home, you are going to experience the stack effect. To prevent this scenario, seal these exit and entry points.  

Rising air:  When warm indoor air rises, it creates space for cooler outdoor air to replace it. Both types of air have different densities and will automatically arrange themselves regardless of the temperature. The warm air rises to the top and the cool air settles at the bottom.  

Airborne particles: Studies show that about 50% of the air in your basement or crawl space ends up in your living areas, thanks to the stack effect. This air not only brings with it moisture from the basement or crawl space, but also tiny airborne particles like dust mites, spores, allergens, and a host of other harmful microorganisms. These microbes can affect your health. 

Problems Caused by the Stack Effect 

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: 

If your home is being impacted by the stack effect and excess moisture, contact a Foundation Recovery Systems professional for a free inspection and repair quote today.

How to Manage The Stack Effect 

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. 
  • Dehumidifiers: Dehumidifiers 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. 

Stack Effect FAQs

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. 

Want to Fix the Stack Effect? 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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